Hypertension Knowledge and Treatment Initiation

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from PEER REVIEW HISTORY

BMJ Open publishes all reviews undertaken for accepted manuscripts. Reviewers are asked to complete a checklist review form (http://bmjopen.bmj.com/site/about/resources/checklist.pdf) and are provided with free text boxes to elaborate on their assessment. These free text comments are reproduced below.

ARTICLE DETAILS

TITLE (PROVISIONAL) Hypertension knowledge and treatment initiation, adherence, and discontinuation among adults in Chennai, India: a cross-sectional study AUTHORS Sudharsanan, Nikkil; Ali, Mohammed; McConnell, Margaret

VERSION 1 – REVIEW

REVIEWER Mayowa Owolabi University of Ibadan, Nigeria REVIEW RETURNED 27-Jun-2020

GENERAL COMMENTS This cross-sectional design was able to identify some behavioral /belief factors associated with BP control in India. Due to the study design, predictors of clearly defined outcomes could not be established. This limitation could be emphasized by the authors. It is also not clear why factors such as cost, availability, affordability, social/family support and frequency of doses were not explored.

REVIEWER Sophie Galson

Duke, USA http://bmjopen.bmj.com/ REVIEW RETURNED 15-Jul-2020

GENERAL COMMENTS This paper describes the gaps in care for hypertensive patients in Chennai, India. While this is a timely and very important topic, there are major flaws in methods utilized that likely resulted in a biased sample and questionable BP readings. The authors also have not fully researched the qualitative literature on HTN in

LMICS or taken advantage of universal guidelines to obtain BP on October 1, 2021 by guest. Protected copyright. measurements in research studies or validated tools to determine knowledge, attitudes and practices regarding hypertension care.

Title – the care “continuum” is still unclear to me and was not fully explored in this paper

Intro – Line9 -sounds like you plan to describe the care in all of India

Methods How were patients selected – randomly?, cluster design? How did you investigate reasons- in-depth interviews/ focus groups?

Results

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from It is unclear why you have separated all the data by gender as this does not seem to be a primary focus of your paper.

Conclusion Contradicts what was just said in last line of the results

Strength - how is your data population-based since this is not a true a random sample?

Intro

Page 4 Line 17- do you mean as the county ages or the population ages? Page 4, Line 33- there have been many papers looking at gaps in HTN care in LMICs – see citations at end of review Page 4, line 47, what are BP endpoints? What theory in particular leads to these explanation? This section is vague and needs to be more specific. It is not clear how these theories were used to create your hypothesis Page 5, line 8 – remove extra period Page 5, line 6- again, there have been multiple papers looking at gaps in HTN care in LMICs. Be more specific about exactly what gaps in the literature this paper is addressing. Page 5, line 10 – the “care continuum” is never fully described in this paper. It is unclear where patients are diagnosed, where they get care, how they follow-up ect…

Methods

Need more info about Chennai – setting section? This is important to see if your sample is actually representative of the population.

Sampling – there are many weaknesses in your methods which need to be addressed and/or commented on in the limitations (in http://bmjopen.bmj.com/ addition to the ones already mentioned). Were your sampling methods based on any previously described techniques? How did you decide which respondent to use if there were multiple in the household? How did you choose a starting point in the ward? Did you go back if to the house if no one was home? How did you attempt to enroll an equal number of men and women? 1/3 of participants refused participation –do you have data about this

group at all? Gender or age? Were the survey teams locals? Also on October 1, 2021 by guest. Protected copyright. when was this survey conducted and by whom?

Measurements Two BP measurements separated by 1 min and then using only the 2nd value does not make sense with any international or Indian guidelines for obtaining BP measurements ? Also, taking BP 2 mins into visit does not negate white coat hypertension. I am concerned about the accuracy of this measurement.

In regards to the beliefs about medicine questionnaire developed in 1999 – was it validated in the population? There are more recent questionnaire tools that have been validated- why was one of these not used?

Explanatory variables What was the piloting process? Were the cards pictures? Has this card technique been used before or validated? The reference

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from provided (24) does not give an explanation about why this technique was chosen. What language was this done in?

Results Based on the multiple CI reported that cross zero many of the “findings” reported are likely due to chance alone. Page 14, line 36: This CI crosses 0 so this is not a “strong association”. Page 15, line 17: 6% difference w/ CI that crosses zero is likely due to chance It is unclear why you have separated all the data by gender as this does not seem to be a primary focus of your paper. If want to explore further this article might be of interest Stroope S. Seclusion, decision-making power, and gender disparities in adult health: Examining hypertension in India. Soc Sci Res. 2015;53:288-299. doi:10.1016/j.ssresearch.2015.05.013

Discussion Page 16, line 17-24 – how do your results suggest that addressing knowledge and exploring reason for BP control will causally “improve the effectiveness of efforts to control BP?” Page 16, line 33 – were they really hypertensive or were the just nervous about having strangers in their house? As above - taking BP 1 min into visit does not negate white coat hypertension. Page 16, 42 –not clear that how this study about TB can be applied to HTN

Page 17, line 40 – well written/explained paragraph

Limitations – see methods section

Page 19, line 26 – would not use the term population-based as this was not a representative sample and would say this is one of the first studies in India rather than LMICs – please expand your http://bmjopen.bmj.com/ literature search. Here are some examples of papers addressing gaps in HTN care in LMICs ( this was from a very brief lit search for Africa alone!) Chang H, Hawley NL, Kalyesubula R, et al. Challenges to hypertension and diabetes management in rural Uganda: a qualitative study with patients, village health team members, and health care professionals. Int J Equity Health. 2019;18(1):38.

doi:10.1186/s12939-019-0934-1 on October 1, 2021 by guest. Protected copyright. Yan LD, Chirwa C, Chi BH, et al. Hypertension management in rural primary care facilities in Zambia: a mixed methods study. BMC Health Serv Res. 2017;17(1):111. doi:10.1186/s12913-017- 2063-0 Odusola AO, Stronks K, Hendriks ME, et al. Enablers and barriers for implementing high-quality hypertension care in a rural primary care setting in Nigeria: perspectives of primary care staff and health insurance managers. Glob Health Action. 2016;9:29041. doi:10.3402/gha.v9.29041 Odusola AO, Hendriks M, Schultsz C, et al. Perceptions of inhibitors and facilitators for adhering to hypertension treatment among insured patients in rural Nigeria: a qualitative study. BMC Health Serv Res. 2014;14:624. doi:10.1186/s12913-014-0624-z Zack RM, Irema K, Kazonda P, et al. Determinants of high blood pressure and barriers to diagnosis and treatment in Dar es Salaam, Tanzania. J Hypertens. 2016;34(12):2353-2364. doi:10.1097/HJH.0000000000001117

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from Lulebo AM, Mapatano MA, Kayembe PK, Mafuta EM, Mutombo PB, Coppieters Y. Assessment of hypertension management in primary health care settings in Kinshasa, Democratic Republic of Congo. BMC Health Serv Res. 2015;15:573. doi:10.1186/s12913- 015-1236-y Rachlis B, Naanyu V, Wachira J, et al. Identifying common barriers and facilitators to linkage and retention in chronic disease care in western Kenya. BMC Public Health. 2016;16:741. doi:10.1186/s12889-016-3462-6 Ofili MI, Ncama BP, Sartorius B. Hypertension in rural communities in Delta State, Nigeria: Prevalence, risk factors and barriers to health care. Afr J Prim Health Care Fam Med. 2015;7(1):875. doi:10.4102/phcfm.v7i1.875 Parker A, Nagar B, Thomas G, Badri M, Ntusi NBA. Health practitioners’ state of knowledge and challenges to effective management of hypertension at primary level. Cardiovasc J Afr. 2011;22(4):186-190. doi:10.5830/CVJA-2010-066

REVIEWER Lori Ann Spies Baylor University USA REVIEW RETURNED 03-Aug-2020

GENERAL COMMENTS Abstract - The hypertension care continuum is not clearly defined and aspects of prevention are omitted in the abstract and in the study. The authors state "We describe the hypertension care continuum among adults diagnosed with hypertension and investigate reasons for gaps at each continuum step" is a strong plan but it is not clearly executed in the manuscript. 1 & 3 Clearly stated objectives and prespecified hypotheses missing 9 & 10 -The research questions and objectives are not clearly defined. The reference to multiple theories makes it unclear what

components are being considered is being considered. http://bmjopen.bmj.com/ This is a readable and interesting manuscript although there is clarity lacking on how the theories were used in the study design and a few punctuation and grammatical errors throughout. The study generally is an interesting contribution to an important topic in an understudied population.

VERSION 1 – AUTHOR RESPONSE on October 1, 2021 by guest. Protected copyright.

Reviewer 1

1. Due to the study design, predictors of clearly defined outcomes could not be established. This limitation could be emphasized by the authors.

We thank the reviewer noting this limitation and have included it as one of the limitations in the "strengths and limitations of the study" section at the start of the paper:

Our study was not designed to estimate the causal effect of individuals' knowledge and beliefs on blood pressure outcomes and is best interpreted as hypothesis generating.

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from We also acknowledge this in the limitations section the manuscript (page 18, end of the first paragraph):

Lastly, we described differences in BP outcomes based on individuals' knowledge and beliefs and not the causal effect of these factors on BP. The results of our paper are thus best interpreted as hypothesis generating.

2. It is also not clear why factors such as cost, availability, affordability, social/family support and frequency of doses were not explored.

We thank the author for raising this question and agree with the reviewer that factors such as cost and availability are important for BP control. The main focus of our paper was on the role of hypertension knowledge. This is because there is currently little evidence on knowledge of the importance of hypertension control and how to control blood pressure in the Indian context. In contrast, there are several existing studies that examine the factors mentioned by the reviewer. Therefore, we believed that studying knowledge would provide the greatest contribution to the existing literature since even if medicines are affordable and available, individuals' may not choose to use them if they are not knowledgeable on the importance of BP control and how to control BP.

Reviewer 2

Abstract comments

1. Title – the care “continuum” is still unclear to me and was not fully explored in this paper

We thank the reviewer for noting this. The concept of the care continuum tries to map out the processes from diagnosis to controlled blood pressure and identify the steps in that pathway that are suboptimal, at the clinic or community population level. Here, we did not present results on http://bmjopen.bmj.com/ the entire continuum. Based on the reviewers' suggestions from our first submission, we have revised the paper to focus more clearly on the part of the continuum that covers daily treatment use since this is a key issue in the literature on hypertension control and the main contribution of our paper for the urban Indian context. We have revised our title to reflect this change.

2. Intro –Line9 -sounds like you plan to describe the care in all of India

on October 1, 2021 by guest. Protected copyright. We have revised this sentence to make it clear that our study is only for Chennai:

We describe hypertension knowledge, treatment patterns, and reported reasons for treatment non-use among adults with diagnosed hypertension in Chennai, India.

3. Methods - How were patients selected – randomly?, cluster design?

We have revised this sentence to make it clear that we selected individuals by surveying doorto- door within randomly sampled clusters (wards):

We collected data on 833 adults ages 30+ with physician diagnosed hypertension using a door-to-door household survey within randomly selected wards of Chennai.

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from 4. Methods - How did you investigate reasons- in-depth interviews/ focus groups?

We have revised the methods section of the abstract to be clear that our results are based on a household survey and that we investigate reasons based on individuals' own self-reports of why they are not taking daily medications.

5. Results - It is unclear why you have separated all the data by gender as this does not seem to be a primary focus of your paper.

We thank the reviewer for noting this inconsistency and have revised the abstract and main text to present results for both sexes combined.

6. Conclusion - Contradicts what was just said in last line of the results

We have revised the conclusion to be clear that our main findings were between knowledge of medications in particular and daily treatment use (as described in the results section):

There were large gaps in consistency of BP medication use which were strongly associated with knowledge about BP medications. Further research is needed to identify whether addressing beliefs can improve daily treatment use among individuals with diagnosed hypertension.

7. Strength - how is your data population-based since this is not a true a random sample?

We thank the reviewer for catching this source of confusion - we used population-based to indicate that respondents were drawn from the general population rather than from a clinic or hospital. However, we agree that this could be unclear and have removed "population-based" from the strengths section.

http://bmjopen.bmj.com/

Introduction comments

8. Page 4 Line 17- do you mean as the county ages or the population ages?

We have revised this line to be clear that we are referring to population aging in India.

on October 1, 2021 by guest. Protected copyright. 9. Page 4, Line 33- there have been many papers looking at gaps in HTN care in LMICs – see citations at end of review

We thank the reviewer for this point and for providing citations to relevant papers. Based on the reviewers' comments, we have refocused our paper specifically around the issue of daily treatment use among those who are diagnosed with hypertension, as this is a major contributor to suboptimal hypertension outcomes in India. We updated the introduction paragraph around this focus and have now included several relevant papers from the literature. We now note, for example, that there have been several papers documenting low treatment use among those with diagnosed hypertension and poor knowledge of hypertension consequences in India, but there is limited evidence on the reasons behind these non-daily treatment use, knowledge of medications and how to correctly use them, and on the link between knowledge and treatment behavior.

10. Page 4, line 47, what are BP endpoints?

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from BP endpoints are the negative health events that result from uncontrolled hypertension, such as stroke and heart disease; however, we have removed this jargon from the manuscript to be clearer.

11. What theory in particular leads to these explanations? This section is vague and needs to be more specific. It is not clear how these theories were used to create your hypothesis

We thank the reviewer for this comment and have substantially revised this section to be more focused. Specifically, rather than investigate several different theoretically motivated potential drivers of hypertension treatment, we focus specifically on knowledge of the importance of hypertension control and the most effective ways of controlling hypertension (starting page 4, last paragraph):

Knowledge of the importance and most effective ways of controlling BP is critical for initiating and adhering to hypertension treatment.(13–16) Individuals may not initiate or adhere to treatment if they are not fully aware of the negative consequences of uncontrolled hypertension. Alternatively, individuals may understand the importance of BP control, but not know that taking medications daily is the most effective way of controlling BP. Limited qualitative evidence from India suggests that individuals with hypertension are not aware of the link between hypertension and stroke and heart disease, and while individuals are generally aware of the importance of healthy lifestyle habits, they do not necessarily understand the specific and most effective ways of controlling BP.(17,18) These largely qualitative studies have focused more on knowledge of preventative measures than knowledge of BP medications and did not link knowledge to medication adherence.

12. Page 5, line 8 – remove extra period

We thank the reviewer for catching this error.

13. Page 5, line 6- again, there have been multiple papers looking at gaps in HTN care in LMICs. Be http://bmjopen.bmj.com/ more specific about exactly what gaps in the literature this paper is addressing.

We agree with the reviewer that our initial framing was not clear on the unique contribution of this manuscript. As mentioned previously, our revised manuscript now focuses tightly on the issue of non-daily treatment use among Indians with diagnosed hypertension, as this is a major contributor to gaps in overall hypertension control in India and because there are very few studies that have comprehensively measured hypertension knowledge and none that have specifically examined on October 1, 2021 by guest. Protected copyright. knowledge of BP medications (the existing literature on hypertension knowledge in India focuses mainly on preventive actions and lifestyle changes such as salt reduction and tobacco cessation).

14. Page 5, line 10 – the “care continuum” is never fully described in this paper. It is unclear where patients are diagnosed, where they get care, how they follow-up ect...

We agree with the reviewers' initial assessment of this limitation and have revised the paper to focus specifically on treatment among those that are diagnosed rather than the entire care continuum.

Methods comments

15. Need more info about Chennai – setting section? This is important to see if your sample is actually representative of the population.

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from Based on the reviewer's suggestions, we have now included a setting section with background information on the sociodemographic characteristics of Chennai (page 6, first paragraph):

Our study was conducted in Chennai, the capital city of the southern state of Tamil Nadu. Tamil Nadu has the 6th highest life expectancy among all Indian states (72.1) and was ranked as having the 9th highest health index -- a composite measured made up of 23 health and health service indicators -- by the Government of India.(19,20) Chennai is the most populous city within the state and the 6th most populous city in India (2011 population of 4.7 million individuals).(21) Chennai has a relatively old age distribution within India: 53% is older than age 30 and 20% older than 50. Hinduism is the most common religion in Chennai (82%), followed by Islam (9%), and Christianity (8%).(22)

16. Sampling – there are many weaknesses in your methods which need to be addressed and/or commented on in the limitations (in addition to the ones already mentioned). Were your sampling methods based on any previously described techniques? How did you decide which respondent to use if there were multiple in the household? How did you choose a starting point in the ward? Did you go back if to the house if no one was home? How did you attempt to enroll an equal number of men and women? 1/3 of participants refused participation –do you have data about this group at all? Gender or age? Were the survey teams locals? Also when was this survey conducted and by whom?

We have expanded our methods and limitations sections to address these points:

Were your sampling methods based on previously described techniques? How did you choose a starting point in the ward?

We used a quota sampling approach. We first randomly sampled wards (the administrative zones for urban India) proportionate to their population size as of the last census. Within wards, enumerators chose a random starting street from the ward map and then went doorto-

door to recruit participants until the quotas for that ward were reached (15-20 respondents, http://bmjopen.bmj.com/ approximately split between men and women and older and younger individuals). We have revised our sampling section to include this information (page 8):

We used a geographically stratified quota sampling approach to identify respondents.(23) We started with randomly selecting 50 of Chennai's 200 wards with weights proportional to share of the Chennai population living in the ward as of the

2011 census. Within selected wards, enumerators selected a random starting street; on October 1, 2021 by guest. Protected copyright. if the starting street was primarily commercial, enumerators moved to parallel streets until they reached a street with residential homes. Enumerators then used a door-to- door two-step procedure to identify eligible individuals.

We used a quota sampling approach rather than a true population-based random sample due to resource constraints. We have revised our paper to acknowledge this limitation in two places. First, in the "strengths and limitations" section at the start of the paper:

The primary limitation of our study is that it is based on a non-probability sample of individuals from a single city in India and may not be generalizable to all urban Indians with hypertension.

Second, in the limitations section (page 17, paragraph 2):

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from Although we randomly selected wards within Chennai, we used a quota sampling approach and did not have a truly population-representative sample because we were not able to randomly sample individuals with physician diagnosed hypertension within wards. This was because random sampling within wards would have required first conducting a household census to determine which households had individuals with confirmed hypertension. This approach was infeasible within our current resources. As a result, our sample may not reflect the general population of adults with physician diagnosed hypertension.

How did you decide which respondent to use if there were multiple in the household? How did you attempt to enroll an equal number of men and women?

We used a quota sampling approach to enroll an approximately equal number of men and women and older and younger individuals within each selected ward. Enumerators would initially enroll all individuals who agreed to participate within a ward and then subsequently only interview those individuals who would result in an approximate balance of sex and broad age group within the ward. If there were multiple potential respondents in the household, the enumerators would enroll the respondent that best balanced the agesex distribution of respondents in that area (top of page 7):

Enumerators interviewed only one respondent per household -- selected by the enumerator to best balance the age and sex distribution of respondents within the ward -- if multiple individuals reported having hypertension.

Did you go back if to the house if no one was home?

Households were only contacted once (page 7, first paragraph): http://bmjopen.bmj.com/ Households were only visited once and not recontacted.

1/3 of participants refused participation –do you have data about this group at all? Gender or age?

We unfortunately do not have information on this group. We have added an additional line in on October 1, 2021 by guest. Protected copyright. the limitations section acknowledging this (top of page 18):

Approximately one-third of contacted individuals did not participate in the survey. Given that we do not have information on these individuals, our results may further misrepresent the Chennai population if those that refused participation were systematically different from those that participated.

Were the survey teams locals? Also, when was this survey conducted and by whom?

The survey teams were local, and data were collected by a Chennai-based research organization in June - August 2019 (page 6, beginning of the "Target population and sampling" section):

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from We recruited individuals aged 30 and older in Chennai who self-reported physiciandiagnosed hypertension between June and August of 2019. Surveys were collected by a Chennai-based research organization that locally recruited survey teams and conducted all interviews in Tamil, the local language.

17. Measurements - Two BP measurements separated by 1 min and then using only the 2nd value does not make sense with any international or Indian guidelines for obtaining BP measurements? Also, taking BP 2 mins into visit does not negate white coat hypertension. I am concerned about the accuracy of this measurement.

We took BP measurements at the end of the interview, usually 15-20 minutes into the visit. However, based on the reviewer’s concern and after consulting with the field teams that collected the data, we have removed the analyses using the blood pressure measurements as we cannot ensure that the measurements accurately represent respondents' true resting blood pressure levels. Our main outcome is now treatment use, consistent with the revised focus of the manuscript.

18. In regards to the beliefs about medicine questionnaire developed in 1999 – was it validated in the population? There are more recent questionnaire tools that have been validated- why was one of these not used?

We thank the reviewer for this comment: we initially used the beliefs in medicine questionnaire as it was used in prior studies in India (although in a limited fashion). However, in our revised manuscript we have removed the analyses using this instrument due to its potential lack of reliability and have focused just on knowledge of hypertension consequences, ways of controlling hypertension, and treatment frequency.

19. Explanatory variables - What was the piloting process? Were the cards pictures? Has this card technique been used before or validated? The reference provided (24) does not give an explanation about why this technique was chosen. What language was this done in? http://bmjopen.bmj.com/ Our piloting process involved asking a small sample of individuals to list all the ways they knew for controlling blood pressure. We then created the cards used as part of the main data collection based on these responses and on the literature on evidence-based methods for blood pressure control. The cards did not have pictures, but spelled out the risk factor in both English and Tamil, the local language. We have revised the manuscript to include this description (pages 8 and 9):

... we presented individuals with cards, each containing a potential way of reducing BP drawn on October 1, 2021 by guest. Protected copyright. from the clinical literature (24). Options included taking medicines, reducing weight, reducing smoking, reducing alcohol consumption, reducing salt consumption, dietary changes other than salt reduction, increasing exercise, and reducing stress and tension. Each option was written on the card in both English and Tamil. Next, we asked individuals which three options they believed were most effective for controlling BP, and among these three, which was the most effective. While there is limited clinical evidence on the impact of reducing stress on blood pressure, we included this option since it was frequently mentioned by individuals during our study piloting, where we conducted qualitative interviews with a small number of respondents and asked them to simply list all the ways they knew of controlling hypertension.

Results comments

20. Based on the multiple CI reported that cross zero many of the “findings” reported are likely due to chance alone.

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from Page 14, line 36: This CI crosses 0 so this is not a “strong association”.

Page 15, line 17: 6% difference w/ CI that crosses zero is likely due to chance

We have revised our results section to focus more closely on knowledge of hypertension consequences, how to most effectively control blood pressure, and correct treatment frequency, reducing the overall number of estimates. We also now only highlight those differences with confidence intervals that do not cross the null and additionally note in several places that these are simple descriptive associations and that further research is needed to determine if they suggest a causal relationship.

21. It is unclear why you have separated all the data by gender as this does not seem to be a primary focus of your paper. If want to explore further this article might be of interest Stroope S. Seclusion, decision-making power, and gender disparities in adult health: Examining hypertension in India. Soc Sci Res. 2015;53:288-299. doi:10.1016/j.ssresearch.2015.05.013

We thank the reviewer for noting this inconsistency and for providing the reference. We have revised our results to not separate by sex, since as the reviewer notes, the sex differences are not a primary focus of this paper.

Discussion comments

22. Page 16, line 17-24 – how do your results suggest that addressing knowledge and exploring reason for BP control will causally “improve the effectiveness of efforts to control BP?”

We thank the reviewer for this comment - indeed our results are descriptive and hypothesis generating and on their own do not imply a causal effect. We have revised this sentence to highlight that the results of our study reveal a strong and suggestive association between BP medicine knowledge and daily treatment use and that future work is needed to determine if improving this knowledge has a causal effect on hypertension treatment (now page 15): http://bmjopen.bmj.com/ Future work is needed to determine whether improving individuals' knowledge that BP medications should be taken daily, even after BP levels reduce, can increase daily treatment use among individuals diagnosed with hypertension in urban India.

23. Page 16, line 33 – were they really hypertensive or were the just nervous about having strangers

Our revised manuscript does not use the blood pressure measurements and instead focuses on treatment use as the primary outcome.

24. Page 16, 42 –not clear that how this study about TB can be applied to HTN

We believe reasons for TB discontinuation are potentially relevant for hypertension because it is another highly prevalent condition in India that requires that individuals take multiple doses of medicines even beyond when they feel or believe that they are cured. We have included this justification in the paragraph (top of page 17):

Our finding, however, is consistent with the tuberculosis literature, another condition that highly prevalent in India and requires that individuals take medicines even after they no longer feel symptoms: a meta-analysis of qualitative studies investigating reasons for poor

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from tuberculosis adherence find that a major reason that individuals do not take their full treatment course is their belief that they have been cured after the initial doses.(33)

25. Page 19, line 26 – would not use the term population-based as this was not a representative sample and would say this is one of the first studies in India rather than LMICs

We have revised this sentence to remove population-based and be more specific about the contribution of our paper (now page 18):

Despite these limitations, our study provides important contributions to the literature on hypertension in LMICs. We provide some of the first evidence on individuals' reported reasons for not taking daily medications and information on BP knowledge and beliefs in a major urban Indian city.

26. Please expand your literature search. Here are some examples of papers addressing gaps in HTN care in LMICs (this was from a very brief lit search for Africa alone!)

We have expanded our literature review around our revised focus of hypertension knowledge and treatment non-use in India, including an additional 6 studies:

Gabert R, Ng M, Sogarwal R, Bryant M, Deepu RV, McNellan CR, et al. Identifying gaps in the continuum of care for hypertension and diabetes in two Indian communities. BMC Health Serv Res. 2017 Dec;17(1):846.

Kusuma YS. Perceptions on hypertension among migrants in Delhi, India: a qualitative study. BMC Public Health. 2009 Dec;9(1):267.

Satish P, Khetan A, Barbhaya D, Agarwal M, Madan Mohan S, Josephson R, et al. A http://bmjopen.bmj.com/ qualitative study of facilitators and barriers to cardiovascular risk factor control in a semiurban population in India. J Fam Med Prim Care. 2019;8(12):3773.

Busingye D, Arabshahi S, Evans RG, Riddell MA, Srikanth VK, Kartik K, et al. Knowledge of risk factors for hypertension in a rural Indian population. Heart Asia. 2019 Feb;11(1):e011136.

on October 1, 2021 by guest. Protected copyright. Kakumani KV, Waingankar P. Assessment of compliance to treatment of diabetes and hypertension amongst previously diagnosed patients from rural community of Raigad District of Maharashtra. J Assoc Physicians India. 2016;64(12):36–40.

Kotian SP, Waingankar P, Mahadik VJ, others. Assessment of compliance to treatment of hypertension and diabetes among previously diagnosed patients in urban slums of Belapur, Navi Mumbai, India. Indian J Public Health. 2019;63(4):348.

We have included a discussion of these papers both in the introduction and discussion sections.

Reviewer 3

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from 1. Abstract - The hypertension care continuum is not clearly defined and aspects of prevention are omitted in the abstract and in the study.

We agree with the reviewers' initial assessment that the continuum is not clearly defined. We have revised our paper to focus specifically on treatment among those that are diagnosed rather than the entire care continuum. We also agree with the reviewer that prevention is an important focus for reducing the burden of hypertension; however, we did not discuss prevention since the focus of our paper was on treatment among individuals who were diagnosed and thus already developed hypertension.

2. The authors state "We describe the hypertension care continuum among adults diagnosed with hypertension and investigate reasons for gaps at each continuum step" is a strong plan but it is not clearly executed in the manuscript.

We thank the reviewer for noting this shortcoming with the initial manuscript. Indeed, we did not present results on the entire continuum. Based on the reviewers' suggestions, we have revised the paper to focus more clearly on the issue of daily treatment use since this is a key issue in the literature on hypertension control and the main contribution of our paper for the urban Indian context.

3. 1 & 3 Clearly stated objectives and prespecified hypotheses missing. 9 & 10 -The research questions and objectives are not clearly defined.

We have revised our manuscript to present the study objectives at the end of the introduction section (page 5, second paragraph):

We investigate the potential reasons behind low hypertension treatment among adults diagnosed with hypertension in Chennai -- India's 6th most populous city. We begin by estimating the share of individuals that do not take daily treatment. We then divide our sample between those who never initiated treatment, those who take treatment but irregularly, and

those who took treatment in the past but have since discontinued it. Among these individuals, http://bmjopen.bmj.com/ we report the most commonly stated reasons for not taking daily treatment. Next, we describe individuals' knowledge of hypertension consequences and treatment and assess whether individuals who are more knowledgeable are also more likely to take daily treatment.

Our paper is primarily descriptive with the aim of generating testable hypotheses. As such, we did not have any prespecified hypotheses. We mention this in the strengths and limitations section at the start of the paper: on October 1, 2021 by guest. Protected copyright.

Our study was not designed to estimate the causal effect of individuals' knowledge and beliefs on blood pressure outcomes and is best interpreted as hypothesis generating.

We also mention this as the last sentence of the limitations section (page 18):

4. The reference to multiple theories makes it unclear what components are being considered is being considered.

We thank the reviewer for this comment and have substantially revised this section to be more focused. Specifically, rather than investigate several different theoretically motivated potential

BMJ Open: first published as 10.1136/bmjopen-2020-040252 on 20 January 2021. Downloaded from drivers of hypertension treatment, we focus specifically on knowledge of the importance of hypertension control and the most effective ways of controlling hypertension (page 4, last paragraph):

5. This is a readable and interesting manuscript although there is clarity lacking on how the theories were used in the study design and a few punctuation and grammatical errors throughout.

Please see our response to the previous question regarding theories. We have also more carefully proofread the revised manuscript for punctuation and grammatical errors.