Comorbid Diabetes and COPD Impact of Corticosteroid Use on Diabetes Complications
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Epidemiology/Health Services Research ORIGINAL ARTICLE Comorbid Diabetes and COPD Impact of corticosteroid use on diabetes complications GILLIAN E. CAUGHEY, PHD ANDREW L. GILBERT, PHD recommendedinpatientswithdiabetes ADRIAN K. PREISS, PHD ELIZABETH E. ROUGHEAD, PHD (9) due to a dose-dependent increase AGNES I. VITRY, PHD in blood glucose levels with corticoste- roid use and increased risk of diabetes progression (10,11). There is little evi- OBJECTIVEd To identify if there is a dose-dependent risk of diabetes complications in dence-based information to facilitate the patients treated with corticosteroids that have both diabetes and chronic obstructive pulmonary treatment of patients with both diabetes disorder (COPD). and COPD, where optimal treatment of RESEARCH DESIGN AND METHODSdA retrospective study of administrative claims COPD with corticosteroids may result data from the Australian Government Department of Veterans’ Affairs, from 1 July 2001 to 30 in a potentially increased risk of diabetes June 2008, of diabetes patients newly initiated on metformin or sulfonylurea. COPD was iden- complications and poorer health out- tified by dispensings of tiotropium or ipratropium in the 6 months preceding study entry. Total comes. This study aimed to examine the corticosteroid use (inhaled and systemic) in the 12 months after study entry was determined. The dose-dependent risk of diabetes-related outcome was time to hospitalization for a diabetes-related complication. Competing risks and complications associated with corticoste- Cox proportional hazard regression analyses were conducted with adjustment for a number of roid use in older patients with diabetes covariates. and COPD. RESULTSdA total of 18,226 subjects with diabetes were identified, of which 5.9% had COPD. Of those with COPD, 67.2% were dispensed corticosteroids in the 12 months from study entry. RESEARCH DESIGN AND Stratification by dose of corticosteroids demonstrated a 94% increased likelihood of hospitali- METHODS zation for a diabetes complication for those who received a total defined daily dose (DDD) of corticosteroids $0.83/day (subhazard ratio 1.94 [95% CI 1.14–3.28], P = 0.014), by comparison with those who did not receive a corticosteroid. Lower doses of corticosteroid (,0.83 DDD/day) Data source and study design were not associated with an increased risk of diabetes-related hospitalization. This study was approved by the Univer- sity of South Australia and the Australian CONCLUSIONSdIn patients with diabetes and COPD, an increased risk of diabetes-related Government Department of Veterans’ Af- hospitalizations was only evident with use of high doses of corticosteroids. This highlights the fairs (DVA) Human Research Ethics Com- need for constant revision of corticosteroid dose in those with diabetes and COPD, to ensure that mittees. A retrospective cohort study was the minimally effective dose is used, together with review of appropriate response to therapy. undertaken from 1 July 2001 to 30 June 2008 using data from the DVA health ad- ministrative claims database. The DVA database contains details of all prescrip- he presence of comorbidity in older ability to perform self-management ac- tion medicines and medical and allied Tpeople with diabetes is common, at tivities necessary for optimal diabetes health services and hospitalizations sub- least 50% will have three or more control and the associated therapeutic sidized by DVA for a treatment popula- comorbid chronic conditions (1,2). Co- challenges (6). tion of 290,000 veterans, war widows, morbidity adds considerable complexity Current guideline treatment recom- and widowers. Over 70% of the popula- to therapeutic management (2) and is a mendations for COPD include the use of tion are 70 years of age or older; 54% are major determinant of functional capabil- inhaled corticosteroids to reduce exacer- male and 9.8% live in residential aged ities and health outcomes (3,4). Chronic bations and improve health status in care, and they are dispensed an average obstructive pulmonary disorder (COPD) patients with moderate to severe COPD of 11 unique medicines annually (12). is a common comorbidity; ;10% of pa- who have frequent exacerbations (7,8). Within the dataset, medicines are coded tients with diabetes will have COPD (1,2). Oral corticosteroids are also recommen- according to the World Health Organiza- COPD is a progressive, largely nonrevers- ded for the short-term treatment of exac- tion (WHO) anatomical and therapeutic ible pulmonary disease that is a major erbations to improve lung function and chemical (ATC) classification (13) and the cause of morbidity and mortality world- hypoxemia and to reduce recovery time, Schedule of Pharmaceutical Benefits item wide (5). COPD is associated with in- but are not recommended chronically codes (14). Hospitalizations are coded creased complexity of care in those with due to their unfavorable risk/benefit according to the WHO Australian modi- diabetes, potentially the result of a reduced profile (7,8). Corticosteroids are not fication of the ICD-10 (ICD-10-AM) clas- sification (15). ccccccccccccccccccccccccccccccccccccccccccccccccc From the Quality Use of Medicines and Pharmacy Research Centre, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia. Cohort selection Corresponding author: Gillian E. Caughey, [email protected]. Subjects were included if they were eligi- Received 26 October 2012 and accepted 29 March 2013. ble for all health services subsidized by DOI: 10.2337/dc12-2197 © 2013 by the American Diabetes Association. Readers may use this article as long as the work is properly DVA in the 12 months prior to the date cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/ of their first (index) dispensing of an licenses/by-nc-nd/3.0/ for details. oral antidiabetic medicine. The study care.diabetesjournals.org DIABETES CARE 1 Diabetes Care Publish Ahead of Print, published online June 4, 2013 Corticosteroids and diabetes complications included new users of either metformin or bioavailability of inhaled corticosteroids those medicines used to identify pa- sulfonylurea medicines, defined by those by comparison with that of oral cortico- tients), number of visits to an endocrinol- who did not have a dispensing of these steroids, the WHO-defined dose of in- ogist, number of visits to a pulmonary medicines in the 12 months prior. Users haled corticosteroids was reduced by a specialist, number of hospitalizations for of other classes of diabetes medicines factor of 10 (18). Users of corticosteroids conditions other than diabetes, exposure (insulin, other oral medications, and were stratified into three groups: .0to to corticosteroids in the 12 months prior combination of metformin) were ex- ,0.25, $0.25 to ,0.83, and $0.83 to study entry, and glycated hemoglobin cluded, as prescription of these medicines DDD/day. (HbA1c) testing in the 12 months prior to at the initiation of diabetes treatment is study entry. All covariates were time vary- not recommended as first-line pharmaco- Outcome definition ing, adjusted at study entry and then an- therapy and may relate to unusual clinical The study end point was time until first nually, apart from age, socioeconomic circumstances (16). Newly initiated med- hospitalization for a diabetes-related status, prior corticosteroid exposure, icine users were selected for study as these complication, defined by the ICD-10- and HbA1c testing, which were adjusted patients are less likely to have existing AM codes E11 and E13–E14 (15). These at baseline only. The subproportional complications than those who are on sec- include diabetic hyperosmolarity with or hazards assumption was confirmed by ex- ond- and third-line agents (insulin or without coma, diabetic ketoacidosis with amining log[2log(survival)] curves, and other oral medications) (16). Comorbid or without coma, diabetic nephropathy, no violation was detected. We also exam- COPD was identified from medicine use, diabetic retinopathy, diabetic neuropa- ined cause-specific Cox proportional haz- defined as two dispensings of tiotropium thy, diabetic angiopathy, and diabetic ar- ard models, with death censored and or ipratropium (ATC codes R03BB04 and thropathy. Follow-up commenced 12 adjusting for the same covariates as in- R03BB01, respectively) in the 6 months months from index dispensing of antidia- cluded in the competing risks regression preceding the first dispensing of the oral betes medicine. Participants were cen- analyses, to provide a more complete un- antidiabetic medicine. Figure 1 shows the sored at death or study end. derstanding of the association between flowchart of the study cohort selection corticosteroid use and time until diabetes criteria. Statistical analyses complication (22). Statistical analyses We used an intention-to-treat approach were performed using SAS 9.2 and Stata Calculation of corticosteroid dose to compare risk of diabetes complications 11.0. The total cumulative corticosteroid dose between users and nonusers of cortico- (both inhaled and systemic [oral], ATC steroids in our diabetes and COPD cohort. RESULTSdA total of 1,077 (5.9%) of codes R01AD-R03BA and H02AB01- These analyses assessed the effect of treat- the 18,226 patients with diabetes had AB10, respectively) was calculated in the ment in the first 12 months from incident comorbid COPD. In the 12 months after 12 months from study entry and converted antidiabetes medicine use. Characteristics study entry, corticosteroids were used by to a defined daily dose (DDD) per day of nonusers and users of corticosteroids 724 (67.2%) of those with diabetes and (17). In order to account for the systemic were compared using a Mann-Whitney COPD. For those who received a cortico- U test for continuous variables and x2 test steroid, the median corticosteroid dose for categorical variables. As death is a over the 12-month period was 0.34 DDD/ competing risk event in this elderly study day (IQR 0.11–0.83). The characteristics population that may preclude the onset of the study cohort at study entry are de- of the outcome of interest (time to hospi- scribed in Table 1.