Association Between Topical Beta-Blockers and Risks

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from PEER REVIEW HISTORY

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ARTICLE DETAILS

TITLE (PROVISIONAL) Association between Topical Beta-Blockers and Risks of Cardiovascular and Respiratory Disease in Glaucoma Patients: a retrospective cohort study AUTHORS Chen, Hsin-Yi; Huang, Wei-Cheng; Lin, Cheng-Li; Kao, Chia-Hung

VERSION 1 – REVIEW

REVIEWER Marques-Neves, Carlos Ophthalmology University Clinic Faculdade de Medicina da Universidade de Lisboa REVIEW RETURNED 27-Oct-2019

GENERAL COMMENTS Some variables are difficult to control nevertheless, the point is achieved.

REVIEWER Reza Razeghinejad Wills Eye Hospital, Philadelphia, PA REVIEW RETURNED 12-Nov-2019

http://bmjopen.bmj.com/ GENERAL COMMENTS A retrospective study on association between Topical Beta- Blockers and Risks of Cardiovascular, stroke, and Respiratory Diseases in Glaucoma Patients reporting higher rate of respiratory issues and stroke in those on beta-blockers. The reported correlations are valid under one condition, being on beta-blocker when the event (stroke, respiratory issues,…..) occurred. The major issue is not including the severity of the systemic diseases and also the severity of glaucoma. on September 25, 2021 by guest. Protected copyright. Although the frequency of DM, HTN, asthma,… were similar between both group, there is no data on the severity of these diseases, for example if the HbA1c of those taking beta blockers is higher it could be the cause of higher rate of stroke not the beta- blockers. Based on the presented data, higher number of those on beta- blockers were taking other groups of glaucoma medications which could indicate greater severity of glaucoma in the beta-blocker group. The hemorrohgic stroke was reported at a higher rate in the beta-blocker group. If it has been secondary to a fall, the chance of fall is greater in patients with severe glaucoma. Some of those who were on beta blockers had asthma.

REVIEWER Dr. Khushwant Yadav SVKM’s NMIMS Deemed to be University, Mumbai, India REVIEW RETURNED 03-Dec-2019

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from GENERAL COMMENTS A well written manuscript. Has explained the concept of linking the topical beta-blockers in Glaucoma with risks in cardiovascular and respiratory diseases.

REVIEWER Syed Hamza Bin Waqar Dow Medical College, Pakistan REVIEW RETURNED 01-Jan-2020

GENERAL COMMENTS Perfectly balanced.

REVIEWER Luis Puente Universidad Complutense de Madrid. Facultad de medicina Spain REVIEW RETURNED 09-Feb-2020

GENERAL COMMENTS This is a retrospective cohort study based in health records and so it has a series of inherent flaws: 1. In health records that have already been collected, not all pertinent risk factors are likely to have been identified and subsequently recorded. Therefore, as is typical of observational studies, only association and not causation can be inferred from the results of the above cohort study. This is because the observed association between glaucoma medications and the outcomes may have been the result of confounding. This is particularly worrisome when the associations are weak (RR< 2). In consequence the authors should be very cautious in their statements, because the evidence they provide is weak. 2. Many different healthcare professionals will have been involved in patient care, so the measurement of risk factors and outcome(s) throughout the database would probably not be fully accurate. It is possible that not all records were complete.

3. If patients who were part of the cohort identified in the above http://bmjopen.bmj.com/ study had incomplete records, it may have biased any observed associations. This will be particularly so if data were not missing at random—that is, if the reason for missing data was related to the risk factor ( medical treatment for galucoma or the outcome(s). 4. The period chosen for inclusion was long (10 years) and it may be difficult to ensure outcomes were measured consistently or using the same criteria. Furthermore the association between the risk factor(s) and the outcome or condition may have changed with time. What may have change the baseline hazard function. on September 25, 2021 by guest. Protected copyright. 5. The time lag between the exposition and the outcome is not shown. While these medications tend to be chronic, changes of treatment may have happened and 6. it is not clear if the patients were on beta blockers or the other medications at the moment at which the outcomes occurred. 7. The authors perform plenty of comparisons, but it is not clear if the adjusted their alfa-error for such a number of statistical tests

Some but not all this limitations are recognized in the limitations section. Specific

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from whether the two populations belong to the same base population (i.e identical in all the characteristics except the expositions analyzed) or from the beginning they had differences which motivated different treatments and could be related to the outcomes. 2. Page 9, line 40 “The propensity score was calculated using a logistic regression model to estimate the probability of the BBCD status”. This is even more puzzling. Are the authors talking about patents without betablockers? 3. Page 9, line 20. Was the exposure to the drugs quantified ( I.e dose x time) 4. Page 10, line 34 We compared the distributions of demographic status…... Please clarify what do you mean by “distributions”. It appears that the authors wanted to mean groups. 5. Page 10,line 34 “demographic status” Do the authors mean demographic data? 6. Page 10, line 55 “The multivariable models were simultaneously adjusted for” I think that “also” fits better than simultaneously in this sentence. 7. Page 10,line 55 s the authors should describe how they managed the missing data 8. Page 10, line 55 s the authors should describe succinctly how they dealt with collinearity if it were present. 9. Page 10,line 55 s The authors must state what covariates were used in the adjusted models. 10. Page 10,line 55 The authors may check if they could find an exposure dependent association ( I.e the higher the exposure the higher the HR) to further strengthen the potential causal association between exposure an outcomes.

11. Table 1. The “p” values are meaningless since the authors matched the two samples, except for medications. None of the http://bmjopen.bmj.com/ differences is therefore the result of randomness, rather they are predetermined by the investigators to be similar or different.

12. Table 2. As the value of “p “is not a measure of the relevance of the differences and the authors already give the confidence interval , the asterisks should be omitted. 13. Table 2 abbreviations must be disclosed in the tables even it has been done in the text. The tables have to be self-reading. 14. Tables 3-4. The authors should clarify what information is on September 25, 2021 by guest. Protected copyright. presented in these tables. Can The “Beta-Blocker or combination drug” already contain any of the other drugs? 15. Tables 3-4. The authors should clarify what information is presented in these tables. Were these pairs of drugs used simultaneously or sequentially?

16. Page 17, line 56 “Second, selection bias was noted in this study. Because the NHIRD database only included patients who sought treatment, those who did not seek treatment may have been recruited into the control cohort”. Weren’t the control cohort also diagnosed from glaucoma? Then wasn’t the medications prescribed by the physicians?. Do you mean whether the patients retired the prescribed medication?

17. Page 13, line 52 “Our study demonstrated that in a large Taiwanese-Chinese population, topical beta-blocker use potentially increases risks of acute respiratory failure and stroke,

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from but not CAD”. Unfortunately the design of the study does not allow to “demonstrate” causality. Use softer words such as “found an association” or something like that. 18. Page 15, line 19 “We believe that a different study will have a different outcome; thus, with regard to stroke, our results cannot be directly compared with the results of others”. This analysis is a bit escapist. If a true causal association between the exposition and an outcome exist, then the design of the study can’t be the reason for having opposite results, rather one of the two studies is biased. The authors have to convince the readers that it is not theirs. The same can be said with other commented associations for which the opposite was found in other studies such as for example CAD.

19. Page 16, line “This finding is very important; clinicians should be cautioned that the risk of respiratory failure increases when BBCD is combined with other glaucoma medications. Furthermore, we observed a statistically significant higher risk of stroke for patients who only used BBCD, both BBCD and CAI, or both BBCD and pilocarpine relative to those who did not use” the authors should be very cautious when recommending changes in clinical practice based in their retrospective observational study which found a weak association between medications and certain outcomes. Particularly when their findings are different from other similar studies.

REVIEWER Marc Saez University of Girona, Spain REVIEW RETURNED 16-Feb-2020

GENERAL COMMENTS The authors attempted to determine if topical beta-blocker use is associated with increased risks of cardiovascular and respiratory diseases in glaucoma patients. The authors have had only partial http://bmjopen.bmj.com/ success in achieving their objective. In fact I have only major comments.

Major comments

1.- The authors use, as the main multivariate model, Cox regression of proportional hazards. However, they do not contrast

or give any evidence that the proportional hazards assumption is on September 25, 2021 by guest. Protected copyright. met. The authors must verify compliance with this assumption, provide the evidence in the article and, in the (very likely) case of non- compliance, use alternative models.

REVIEWER Moritz Tobiasch LKH Hall in Tirol, Austria REVIEW RETURNED 17-Feb-2020

GENERAL COMMENTS Dear madam or sir, thank you for the opportunity to review the above mentioned paper. This work on the incidence of putative adverse effects of

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from topical beta blockers in glaucoma is complementary to two large observational studies with conflicting results. Baseline data, hypothesis, and workup are clearly formulated. The research question is definitively relevant, and in the light of the two cohorts already published, a valuable contribution.

However, I feel that some arguments need clarification, and I would like to encourage the authors to address the following points: - As a general objection, if the influence of a specific risk factor were to be assessed, a secondary nested case-control study would probably be a more appropriate approach (i.e., among all patients with glaucoma and acute resp. failure, how many had been exposed to BBCD in comparison to those in the group without ARF). - In the paper, solely the nonselective beta blocker timolol is explicitly mentioned. Are there other compounds in ophthalmologic use, e.g., the far better studied propranolol or (the one NSBB with cardiovascular mortality benefit) carvedilol? If not, the presented data might only be extrapolated to timolol. - In order to gain an impression of the effect sizes in discussion, I would like to ask the authors if a small meta-analysis on available data was possible or not, and if this cumulative effect size changed after inclusion of the data presented here. - In the article, most strikingly in the discussion, there are contraindications to beta blocker therapy mentioned that do not reflect the current standard of care in many regions. E.g., in patients with myocardial infarction, beta blocker use is a grade Ia recommendation, and they have an important role in rate control in patients with atrial fibrillation. COPD patients, if on beta-1-selective agents (metoprolol, bisoprolol) should not be taken off their medication even in case of mild exacerbations. Please review these sections and clarify, if nonselective beta blockers, or beta http://bmjopen.bmj.com/ blockers in general are ment. - The endpoints of the study need further clarification, particularly the point "acute respiratory failure", which comes in at least two forms, being either primarly hypoxemic (as in lung edema secondary to acute left ventricular failure) or hypercapnic (as in COPD or emphysema exacerbations). I would like to ask the authors if a subtyping of acute respiratory failure was performed, and what the clinical criteria for this diagnosis consisted of (paO2? paCO2? arterio-alveolar gradient? Need for bronchodilatatory on September 25, 2021 by guest. Protected copyright. agents?). - if not familiar with pharmacokinetics, one cannot easily guess which systemic effects of drugs topically applied to the eye are probable. If any estimate is available which dose of the drug will appear in the systemic circulation, this would help the discussion a lot. - In your statistical workup, it seems that patients in the BBCD group were on quite some more medication than in the other group, making the assumption likely that this group was generally more prone to complications. This bias could possibly be circumvented by re-analysing the dataset as a case-control study, instead of a (challenging and intrinsically not very transparent) propensity-score matching.

A few smaller points include the following: - the sentence starting in line 29 ("Glaucoma pt ...") reads as if OAG and ACG referred to a subtype of cardiovascular disease. I'd suggest to rephrase that sentence.

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from - I was unable to locate one reference (Parsons 2001, #15)

Thank you again for giving me the opportunity to review this paper. I would be happy to see the revised version.

VERSION 1 – AUTHOR RESPONSE

Reviewer: 1 Some variables are difficult to control nevertheless, the point is achieved. Reply: Thanks for your positive comment for our study.

Reviewer: 2 A retrospective study on association between Topical Beta-Blockers and Risks of Cardiovascular, stroke, and Respiratory Diseases in Glaucoma Patients reporting higher rate of respiratory issues and stroke in those on beta-blockers. The reported correlations are valid under one condition, being on beta-blocker when the event (stroke, respiratory issues,…..) occurred. The major issue is not including the severity of the systemic diseases and also the severity of glaucoma. Although the frequency of DM, HTN, asthma,… were similar between both group, there is no data on the severity of these diseases, for example if the HbA1c of those taking beta blockers is higher it could be the cause of higher rate of stroke not the beta-blockers. Based on the presented data, higher number of those on beta-blockers were taking other groups of glaucoma medications which could indicate greater severity of glaucoma in the beta-blocker group. The hemorrohgic stroke was reported at a higher rate in the beta-blocker group. If it has been secondary to a fall, the chance of fall is greater in patients with severe glaucoma. Some of those who were on beta blockers had asthma. Reply: Thanks so much for your nice comments. Because of the inherent limitation of the claims database, the severity of systemic disease and glaucoma is not available. We would like to address http://bmjopen.bmj.com/ this limitation in the discussion part. Because there are 7 reviewers in our study, some reviewers strongly suggest us to do some changes in the study design, including the statistical method. Therefore, the new results are a little different from previous version. We also address all the findings in the discussion part.

Reviewer: 3

A well written manuscript. Has explained the concept of linking the topical beta-blockers in Glaucoma on September 25, 2021 by guest. Protected copyright. with risks in cardiovascular and respiratory diseases. Reply: Thanks so much for your positive comment about our study.

Reviewer: 4 Perfectly balanced. Reply: Thanks so much for your positive comment about our study.

Reviewer: 5 This is a retrospective cohort study based in health records and so it has a series of inherent flaws: 1. In health records that have already been collected, not all pertinent risk factors are likely to have been identified and subsequently recorded. Therefore, as is typical of observational studies, only association and not causation can be inferred from the results of the above cohort study. This is because the observed association between glaucoma medications and the outcomes may have been the result of confounding. This is particularly worrisome when the associations are weak (RR< 2). In consequence the authors should be very cautious in their statements, because the evidence they provide is weak.

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from Reply: Thanks for the great comments. After careful evaluation of our previous study design and methodology, we have decided to do some changes in the revised version according to your opinions. We have tried to use another statistical model as sensitivity analysis. The BBCD use was quantified as a binary variable every 6 months. Due to frequency variations in BBCD use among patients with glaucoma during the study period, BBCD were considered as time-dependent covariates in the Cox proportional hazards models to compute the hazard ratios (HRs) and their 95% confidence intervals (CIs) for outcome in BBCD users when compared to non- BBCD users. The results will be presented in the new Table 3.

2. Many different healthcare professionals will have been involved in patient care, so the measurement of risk factors and outcome(s) throughout the database would probably not be fully accurate. It is possible that not all records were complete. Reply: Thanks for the comments. LHID 2000 was a sample of people receiving health care and the health care institutions made the reimburse claims. We performed the present study using the claims data. The dataset of LHID has been established since 1996 based on insured population of 2000 and updated annually hereafter. We established our study cohorts using the claims data of 2000-2010. The diagnosis of risk factors and outcome(s) was identified with at least 3 claims for outpatient and/or hospitalization visits based on ICD-9-CM code.

3. If patients who were part of the cohort identified in the above study had incomplete records, it may have biased any observed associations. This will be particularly so if data were not missing at random—that is, if the reason for missing data was related to the risk factor ( medical treatment for galucoma or the outcome(s). Reply: Thanks for the comments. The dataset of LHID2000 was established based on population registered in 2000 regardless of their health status. Their medical records were extracted annually from 1996 through 2011as a chronological data set. People in Taiwan may walk in a clinic or hospital easily for medical attention. Therefore, most of insured persons had been included in the claims.

http://bmjopen.bmj.com/ 4. The period chosen for inclusion was long (10 years) and it may be difficult to ensure outcomes were measured consistently or using the same criteria. Furthermore the association between the risk factor(s) and the outcome or condition may have changed with time. What may have change the baseline hazard function. Reply: Thanks for the comments. We used another statistical models to observe the BBCD use changed with time. The BBCD use was quantified as a binary variable every 6 months. Due to frequency variations in BBCD use among patients with glaucoma during the study period, BBCD were on September 25, 2021 by guest. Protected copyright. considered as time-dependent covariates in the Cox proportional hazards models to compute the hazard ratios (HRs) and their 95% confidence intervals (CIs) for outcome in BBCD users when compared to non- BBCD users. The new result has been presented in Table 3.

5. The time lag between the exposition and the outcome is not shown. While these medications tend to be chronic, changes of treatment may have happened and Reply: Thanks for the comments. This study was, in fact, a retrospective cohort study, because the studied individuals were identified since 2000 and were followed forward retrospectively in the database. Since cohort studies have the merit of no temporal ambiguity between the exposure and outcome. Because patients with BBCD use changed irregularly during follow-up, we considered statins a time-dependent covariate in the Cox proportional hazard model to illustrate the effect as hazard ratios (HRs) and corresponding 95% confidence intervals (CIs). The time-dependent covariate of the BBCD meant that the comparison may represent each 6 month period for the same subject and drug exposure variables, presented as a yes or no (binary) variable.

6. it is not clear if the patients were on beta blockers or the other medications at the moment at which

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from the outcomes occurred. Reply: Thanks for the comments. We deleted the patients on beta blockers or the other medications at the moment at which the outcomes occurred. All the follow-up period must more than zero, without included equal zero.

7. The authors perform plenty of comparisons, but it is not clear if the adjusted their alfa-error for such a number of statistical tests Reply: Thanks for the comments. The Bonferroni method of multiple comparisons was set the p-value value at 0.0125. We have considered the multiple comparisons in the revised manuscript (Please see the revised Table 2).

Some but not all this limitations are recognized in the limitations section. Specific

1. Page 9, linr 40 : “Individuals without BBCD use were selected from the LHID2000 and matched to the BBCD cohort at a ratio of 1:1 based on the propensity score [15”]”. As the selection of the cohorts is key to understand potential biases, the authors need to explain very clearly what characteristic or characteristics were “matched” with this propensity score. What it at stakes here is whether the two populations belong to the same base population (i.e identical in all the characteristics except the expositions analyzed) or from the beginning they had differences which motivated different treatments and could be related to the outcomes. Reply: Thanks for the comments. Patients with glaucoma who used BBCD were matched (1:1 ratio) with those who did not use BBCD according to their propensity score through nearest neighbor matching, initially to the eighth digit and then as required to the first digit. Therefore, matches were first made within a caliper width of 0.0000001, and then the caliper width was increased for unmatched cases to 0.1. We reconsidered the matching criteria and performed a rematch (greedy algorithm). For each glaucoma patient on BBCD use, the corresponding comparisons were selected

based on the nearest propensity score. http://bmjopen.bmj.com/

2. Page 9, line 40 “The propensity score was calculated using a logistic regression model to estimate the probability of the BBCD status”. This is even more puzzling. Are the authors talking about patents without betablockers? Reply: Thanks for the comments. Yes, patients with glaucoma who used BBCD were matched (1:1 ratio) with those who did not use BBCD according to their propensity score.

on September 25, 2021 by guest. Protected copyright. 3. Page 9, line 20. Was the exposure to the drugs quantified ( I.e dose x time) Reply: Thanks for the comments. Patients who had received BBCD treatment for more than 28 days were defined as the users of the treatment. We used time-dependent covariates in the Cox proportional hazards models to observe the BBCD use changed with time as dose effect.

4. Page 10, line 34 We compared the distributions of demographic status…... Please clarify what do you mean by “distributions”. It appears that the authors wanted to mean groups. Reply: Thanks for the comments. We changed the “distributions” to “proportions”.

5. Page 10,line 34 “demographic status” Do the authors mean demographic data? Reply: Thanks for the comments. We corrected it.

6. Page 10, line 55 “The multivariable models were simultaneously adjusted for” I think that “also” fits better than simultaneously in this sentence. Reply: Thanks for the comments. We corrected it.

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from 7. Page 10,line 55 s the authors should describe how they managed the missing data. Reply: Thanks for the comments. Our study is based on the reimbursement database of the Taiwan National Health Insurance Database. Therefore, hospital contact is required. The Taiwan National Health Insurance program covers over 99% of the population and is a single-payer system. The total insurants nearly represent the entire population. Because it is a government-managed database, the proportion of missing data is low. We only analyze the completed data.

8. Page 10, line 55 s the authors should describe succinctly how they dealt with collinearity if it were present. Reply: Thanks for the comments. We calculated the correlation matrix of regression coefficients, and we find lower correlations among the regression coefficients of all covariates. The highest correlations in our data between the regression coefficients of two covariates, it is 0.01 between the regression coefficients of diabetes mellitus and CKD and the regression coefficients of pneumonia and COPD by Cox model of correlation matrix.

9. Page 10,line 55 s The authors must state what covariates were used in the adjusted models. Reply: Thanks for the comments. We added it.

10. Page 10,line 55 The authors may check if they could find an exposure dependent association ( I.e the higher the exposure the higher the HR) to further strengthen the potential causal association between exposure an outcomes. Reply: Thanks for the comments. Yes, we also used time-dependent covariates in the Cox proportional hazards models to observe the BBCD use changed with time as dose effect. The time- dependent covariate of the BBCD meant that the comparison may represent each 6 month period for the same subject and drug exposure variables, presented as a yes or no (binary) variable. The results have been presented in Table 3.

11. Table 1. The “p” values are meaningless since the authors matched the two samples, except for

medications. None of the differences is therefore the result of randomness, rather they are http://bmjopen.bmj.com/ predetermined by the investigators to be similar or different. Reply: Thanks for the comments. We deleted it.

12. Table 2. As the value of “p “is not a measure of the relevance of the differences and the authors already give the confidence interval , the asterisks should be omitted. Reply: Thanks for the comments. We deleted it.

on September 25, 2021 by guest. Protected copyright. 13. Table 2 abbreviations must be disclosed in the tables even it has been done in the text. The tables have to be self-reading. Reply: Thanks for the comments. We added it.

14. Tables 3-4. The authors should clarify what information is presented in these tables. Can The “Beta-Blocker or combination drug” already contain any of the other drugs? Reply: Thanks so much for your suggestions. After careful evaluation of our previous study design, we have made changes in study design and have deleted the Table 3 -6 based on your concern. A new statistical method was proposed based on your suggestion and new table 3 has been presented.

15. Tables 3-4. The authors should clarify what information is presented in these tables. Were these pairs of drugs used simultaneously or sequentially? Reply: Thanks so much for your suggestions. We have deleted Table 3-6.

16. Page 17, line 56 “Second, selection bias was noted in this study. Because the NHIRD database only included patients who sought treatment, those who did not seek treatment may have been

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from recruited into the control cohort”. Weren’t the control cohort also diagnosed from glaucoma? Then wasn’t the medications prescribed by the physicians?. Do you mean whether the patients retired the prescribed medication? Reply: Thanks so much for your concern. Because our study is based on claims databases, the diagnosis of glaucoma was defined from the ICD coding from the clinicians. We believe there are potential selection bias in this kind of claims databases study. In addition, the control cohort are those who without coding with glaucoma. Because glaucoma medications are costly, most glaucoma patients in Taiwan seek treatment from ophthalmologists. Therefore, the claims database for glaucoma medication usage that was used in this study appears to be reliable

17. Page 13, line 52 “Our study demonstrated that in a large Taiwanese-Chinese population, topical beta-blocker use potentially increases risks of acute respiratory failure and stroke, but not CAD”. Unfortunately the design of the study does not allow to “demonstrate” causality. Use softer words such as “found an association” or something like that. Reply: Thanks so much for kind opinions. We agree with your precious opinions and will be very careful in writing as your suggestion.

18. Page 15, line 19 “We believe that a different study will have a different outcome; thus, with regard to stroke, our results cannot be directly compared with the results of others”. This analysis is a bit escapist. If a true causal association between the exposition and an outcome exist, then the design of the study can’t be the reason for having opposite results, rather one of the two studies is biased. The authors have to convince the readers that it is not theirs. The same can be said with other commented associations for which the opposite was found in other studies such as for example CAD. Reply: Thanks so much for your opinions and comments. We have deleted the table 3-6 and the study design has been changed in the revised version. The discussion will be rewritten. Thanks so much for your kind understanding.

19. Page 16, line “This finding is very important; clinicians should be cautioned that the risk of http://bmjopen.bmj.com/ respiratory failure increases when BBCD is combined with other glaucoma medications. Furthermore, we observed a statistically significant higher risk of stroke for patients who only used BBCD, both BBCD and CAI, or both BBCD and pilocarpine relative to those who did not use” the authors should be very cautious when recommending changes in clinical practice based in their retrospective observational study which found a weak association between medications and certain outcomes. Particularly when their findings are different from other similar studies. Reply: Thanks so much for your opinions and comments. We have deleted the table 3-6. The on September 25, 2021 by guest. Protected copyright. discussion will be rewritten. Thanks so much for your kind understanding.

Reviewer: 6 The authors attempted to determine if topical beta-blocker use is associated with increased risks of cardiovascular and respiratory diseases in glaucoma patients. The authors have had only partial success in achieving their objective. In fact I have only major comments.

Major comments

1.- The authors use, as the main multivariate model, Cox regression of proportional hazards. However, they do not contrast or give any evidence that the proportional hazards assumption is met. The authors must verify compliance with this assumption, provide the evidence in the article and, in the (very likely) case of non-compliance, use alternative models. Reply: Thanks for your comment. Based on the suggestion of two reviewers, we do some changes in the study design and delete the table 3-6. The new result has been presented in table 3. By the way,

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from to address the concern of constant proportionality, we examined the proportional hazard model assumption using a test of scaled Schoenfeld residuals. The results show that there was no significant relationship between Schoenfeld residuals for BBCD and follow-up time (p-value = 0.05, 0.08, 0.66, 0.10, 0.57, respectively) in the model evaluating the pneumonia, stroke, hemorrhagic stroke, ischemic stroke and coronary artery disease risk. The proportional hazard model assumption was applied by using a test of scaled Schoenfeld residuals. In the model evaluating the acute respiratory failure risk throughout overall follow-up period, the results reveal a significant relationship between Schoenfeld residuals for BBCD and follow-up time, suggesting the proportionality assumption was violated (P value =0.02). In the subsequent analyses, we stratified the follow-up duration to deal with the violation of proportional hazard assumption (see new Table 2).

2.- The authors should include in the models the possible existence of modification of the effect (i.e. interaction) between the main explanatory variable and, at least, age and sex. It is very likely that these interactions exist and should therefore be evaluated. Reply: Thanks for your comment. We added the multiplicative interaction of age and sex for adjustment in measuring HR of outcome as your suggestion (see new Table 2).

Reviewer: 7 Dear madam or sir, thank you for the opportunity to review the above mentioned paper. This work on the incidence of putative adverse effects of topical beta blockers in glaucoma is complementary to two large observational studies with conflicting results. Baseline data, hypothesis, and workup are clearly formulated. The research question is definitively relevant, and in the light of the two cohorts already published, a valuable contribution.

However, I feel that some arguments need clarification, and I would like to encourage the authors to

address the following points: http://bmjopen.bmj.com/ - As a general objection, if the influence of a specific risk factor were to be assessed, a secondary nested case-control study would probably be a more appropriate approach (i.e., among all patients with glaucoma and acute resp. failure, how many had been exposed to BBCD in comparison to those in the group without ARF). Reply: Thanks for your comment. Based on the suggestions and opinions of two reviewers (among 7 reviewers), we decided to do some changes in the revised version. The old Tables 3-6 have been deleted. The new result has been presented in table 3 and we have rewritten our finding in the on September 25, 2021 by guest. Protected copyright. discussion part. Thanks for much for your kind understanding. Regarding your suggestion of nested case-control study, we also did the analysis as below (please see Supplement Table 1& 2). The result shows that glaucoma patients with BBCD is only slightly significant associated with pneumonia. Although the result is a little different from the current revised version, we believe that different study design would influence different outcome. We would like address more limitations in the discussion part. Thanks so much for your kind understanding in advance.

Supplement Table 1. Demographic characteristics and odd ratios (ORs) and 95% confidence interval (CI) of Outcomes (including pneumonia, acute respiratory failure, stroke, and coronary artery disease) Outcomes Crude OR (95% CI) Adjusted OR† (95% CI) No Yes (n=4034) (n=4034) Variables n % n %

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from Age, mean (SD)† 68.0 13.0 67.8 12.6 1.00(0.99, 1.00)*** 0.99(0.99, 1.00)*** Stratify age 20-49 352 8.73 374 9.30 1.00 50-64 1125 27.9 1098 27.3 0.92(0.78, 1.09) 65+ 2557 63.4 2562 63.5 0.94(0.81, 1.10) Gender Women 2108 52.3 2099 52.0 1.00 1.00 Men 1926 47.7 1935 48.0 1.01(0.93, 1.10) 1.04(0.95, 1.13) Comorbidity Hypertension 2487 61.6 3038 75.3 1.90(1.72, 2.09)*** 1.93(1.73, 2.14)*** Hyperlipidemia 1587 39.3 1720 42.6 1.15(1.05, 1.25)* 0.92(0.83, 1.01) Diabetes mellitus 901 22.3 1227 30.4 1.52(1.38, 1.68)*** 1.28(1.14, 1.43)*** COPD 1022 25.3 1025 25.4 1.00(0.91, 1.11) 0.96(0.85, 1.07) Asthma 516 12.8 546 13.5 1.07(0.94, 1.21) 1.07(0.93, 1.23) CKD 385 9.54 618 15.3 1.72(1.50, 1.96)*** 1.40(1.21, 1.62)*** Glaucoma medications Beta-Blocker 1506 37.3 1565 38.8 1.06(0.97, 1.16) Combination drug use 123 3.05 147 3.64 1.20(0.94, 1.53) Beta-Blocker or Combination drug use (BBCD) 1533 38.0 1608 39.9 1.08(0.99, 1.18) 1.08(0.97, 1.19) Other glaucoma medications PGA 547 13.6 502 12.4 0.91(0.80, 1.03) 0.82(0.71,0 .96)* CAI 482 12.0 490 12.2 1.02(0.89, 1.17) 0.95(0.82, 1.11) Alpha agonist 476 11.8 471 11.7 0.99(0.86, 1.13) 0.98(0.85, 1.14) Pilocarpine 994 24.6 1058 26.2 1.09(0.98, 1.20) 1.13(1.01, 1.26)* COPD: chronic obstructive pulmonary disease CKD: chronic kidney disease CAI: carbonic anhydrase inhibitor PGA: prostaglandin analog

CAI: carbonic anhydrase inhibitor http://bmjopen.bmj.com/ † Variable found to be statistically significant in the univariable model were further examined in the multivariable model.

Supplement Table 2. Association between Outcomes and Beta-Blocker or Combination drug use Variables n(%) Crude OR (95% CI) Adjusted OR† (95% CI) on September 25, 2021 by guest. Protected copyright. Non-outcome 4034(50.0) 1.00 1.00 Outcomes Pneumonia 1228(23.3) 1.24(1.09, 1.41)** 1.20(1.04, 1.39)* Acute respiratory failure 858(17.5) 1.29(1.11, 1.49)** 1.17(0.99, 1.39) Stroke 1241(23.5) 1.14(1.00, 1.30)* 1.11(0.96, 1.28) Hemorrhagic stroke 181(4.29) 1.05(0.78, 1.43) 1.13(0.80, 1.57) Ischemic stroke 1060(20.8) 1.16(1.01, 1.33)* 1.10(0.95, 1.29) Coronary artery disease 2515(38.4) 1.04(0.92, 1.12) 1.05(0.93, 1.18) † Variable found to be statistically significant in the univariable model were further examined in the multivariable model.

- In the paper, solely the nonselective beta blocker timolol is explicitly mentioned. Are there other compounds in ophthalmologic use, e.g., the far better studied propranolol or (the one NSBB with cardiovascular mortality benefit) carvedilol? If not, the presented data might only be extrapolated to timolol. Reply: Thanks so much for your nice comment. Because the study purpose is to address the use of

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from topical beta-blocker and its association with cardiovascular disease in glaucoma patients. The oral beta-blockers, such as propranolol or others, are not adequate in this study model.

- In order to gain an impression of the effect sizes in discussion, I would like to ask the authors if a small meta-analysis on available data was possible or not, and if this cumulative effect size changed after inclusion of the data presented here. Reply: Thanks for your nice comment. Our study is a cohort study by using a nationalized health insurance database in Taiwan, which is quite few in the literature. The meta-analysis based on available data was not possible.

- In the article, most strikingly in the discussion, there are contraindications to beta blocker therapy mentioned that do not reflect the current standard of care in many regions. E.g., in patients with myocardial infarction, beta blocker use is a grade Ia recommendation, and they have an important role in rate control in patients with atrial fibrillation. COPD patients, if on beta-1-selective agents (metoprolol, bisoprolol) should not be taken off their medication even in case of mild exacerbations. Please review these sections and clarify, if nonselective beta blockers, or beta blockers in general are ment. Reply: Thanks so much for your kind comment. Because the study purpose is to address the use of topical beta-blocker and its association with cardiovascular disease in glaucoma patients but not oral beta-blockers. Topical beta-blocker is the standard ocular hypotensive treatment for glaucoma patients without contraindication to heart or pulmonary disease in ophthalmology field.

- The endpoints of the study need further clarification, particularly the point "acute respiratory failure", which comes in at least two forms, being either primarly hypoxemic (as in lung edema secondary to acute left ventricular failure) or hypercapnic (as in COPD or emphysema exacerbations). I would like to ask the authors if a subtyping of acute respiratory failure was performed, and what the clinical criteria for this diagnosis consisted of (paO2? paCO2? arterio-alveolar gradient? Need for bronchodilatatory agents?).

Reply: Thanks so much for your concern. Because our study is based on a large claims database, the http://bmjopen.bmj.com/ diagnosis was based on ICD coding but not clinical criteria. We will address more about this limitation in the discussion part.

- if not familiar with pharmacokinetics, one cannot easily guess which systemic effects of drugs topically applied to the eye are probable. If any estimate is available which dose of the drug will appear in the systemic circulation, this would help the discussion a lot. Reply: Thanks so much for your concern. Because our study is based on a large claims database, the on September 25, 2021 by guest. Protected copyright. drug effect on systemic circulation of topical eyedrop is not available in this kind of claims database. We would like address more about this limitation in the discussion part.

- In your statistical workup, it seems that patients in the BBCD group were on quite some more medication than in the other group, making the assumption likely that this group was generally more prone to complications. This bias could possibly be circumvented by re-analysing the dataset as a case-control study, instead of a (challenging and intrinsically not very transparent) propensity-score matching. Reply: Thanks for your comment. Regarding your suggestion of nested case-control study, we also did the analysis as below (please see Supplement Table 1& 2). The result shows that glaucoma patients with BBCD is only slightly significant associated with pneumonia. Although the result is a little different from the current revised version, we believe that different study design would influence different outcome. We would like address more limitations in the discussion part. Thanks so much for your kind understanding in advance.

A few smaller points include the following:

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from - the sentence starting in line 29 ("Glaucoma pt ...") reads as if OAG and ACG referred to a subtype of cardiovascular disease. I'd suggest to rephrase that sentence. Reply: Thanks so much for your suggestion.

-- I was unable to locate one reference (Parsons 2001, #15) Reply: The information about # 15 is shown below. https://support.sas.com/resources/papers/proceedings/proceedings/sugi29/165-29.pdf

Thank you again for giving me the opportunity to review this paper. I would be happy to see the revised version.

VERSION 2 – REVIEW

REVIEWER Luis Puente- Maestu Hospital Universitario Gregorio Marañón- Universidad Complutense de Madrid. Madrid, Spain REVIEW RETURNED 19-Apr-2020

GENERAL COMMENTS No further comments

REVIEWER Marc Saez University of Girona, Spain REVIEW RETURNED 25-Apr-2020

GENERAL COMMENTS The authors have answered very well not only my comments but also those of the other reviewers. In addition, they have included a large part of the comments in the new version of the manuscript. I have no further comments.

http://bmjopen.bmj.com/ REVIEWER Moritz Tobiasch Landeskrankenhaus Hall in Tirol, Department of Medicine, Tyrolia, Austria REVIEW RETURNED 04-May-2020

GENERAL COMMENTS I wish to explicitly thank the authors to adress basically all issues raised by the reviewers in the first round. The work is in my

opinion nearly ready for publication, provided one statistical on September 25, 2021 by guest. Protected copyright. questions is made clearer: - as stated in the (very informative!) methods section, for continuous variables, Student's t test was used. This test has gone a little out of fashion as its assumptions are quite rarely met (normal distributions and comparable variances in both groups). Were these assumptions tested before applying these tests, e.g., by a Shapiro-Wilk test? If normality is not met, a non-parametric test would be advisable.

Thank you very much for the thorough workup of the reviews. As a last statement, I would like to encourage the authors to consider to keep the data accessible in some form as a meta-analysis of topical betablockers in glaucoma seems to be only a matter of time.

BMJ Open: first published as 10.1136/bmjopen-2019-034361 on 22 July 2020. Downloaded from VERSION 2 – AUTHOR RESPONSE

Reviewer: 5 Please leave your comments for the authors below No further comments Reply: Thanks so much for your encouragement for our study.

Reviewer: 6 Please leave your comments for the authors below The authors have answered very well not only my comments but also those of the other reviewers. In addition, they have included a large part of the comments in the new version of the manuscript. I have no further comments. Reply: Thanks so much for your support for our study.

Reviewer: 7 Please leave your comments for the authors below I wish to explicitly thank the authors to address basically all issues raised by the reviewers in the first round. The work is in my opinion nearly ready for publication, provided one statistical questions is made clearer: - as stated in the (very informative!) methods section, for continuous variables, Student's t test was used. This test has gone a little out of fashion as its assumptions are quite rarely met (normal distributions and comparable variances in both groups). Were these assumptions tested before applying these tests, e.g., by a Shapiro-Wilk test? If normality is not met, a non-parametric test would be advisable. Reply: Yes, we corrected it. Mann-Whitney U test was used to compare difference between BBCD and non-BBCD cohorts for continuous variables.

Thank you very much for the thorough workup of the reviews. As a last statement, I would like to http://bmjopen.bmj.com/ encourage the authors to consider to keep the data accessible in some form as a meta-analysis of topical betablockers in glaucoma seems to be only a matter of time. Reply: Thank so much for your full support for our study. We are pleased to keep our data accessible for further meta-analysis study. Please feel free to contact us in this issue in the future.

REVIEWER Moritz Tobiasch LKH Hall in Tirol Department of Medicine REVIEW RETURNED 08-Jun-2020

GENERAL COMMENTS The latest concerns of the reviewers have been addressed, in particular, non-parametric tests were run instead of t-tests, and distributions were changed from arithmetic means and 95% confidence intervals to medians and interquartile ranges.