Multiple medication (polypharmacy) and chronic kidney disease in patients aged 60 and older: a pharmacoepidemiologic perspective.

BACKGROUND: Few studies have examined whether there was an independent association between multiple medication use and risk of chronic kidney disease (CKD), with adjustment for cardiometabolic factors. In the study, we aimed to examine this association using a nationally representative sample in CKD patients aged 60 and older. METHODS: In the study, subjects aged ⩾60 years (n = 1306) who participated in the 2011-2012 National Health and Nutrition Examination Survey were analyzed cross-sectionally. CKD was defined using the CKD Epidemiology Collaboration (CKD-EPI) equation i.e. estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m(2). Patients with multiple medications were classified as those having five or more prescription medications per day. All data analysis was performed using SAS 9.3 version. RESULTS: The prevalence of CKD among age group ⩾80 years, age group 70-79 years and age group 60-69 years were 73.26%, 55.76% and 27.03% respectively (p < 0.001). About half of hypertension (HTN) and diabetic patients aged ⩾60 years had CKD. The prevalence of CKD in patients with cardiovascular disease (CVD) was 60.57%. The logistic regression model without adjustment reflects that those on multiple medications (⩾5 medications/day) had 1.53 (1.02-2.31) times as likely (53% increase) to have CKD compared with those on <5 medications/day. After adjustment for age, CVD, HTN and diabetes mellitus (DM), the odds of CKD for multiple medications appeared to have a protective effect, although it did not reach statistical significance. The adjusted odds ratio [95% confidence interval (CI)] was 0.89 (95% CI: 0.60-1.34); it showed an 11% decreased odds of CKD in patients who were taking multiple medications. The adjusted odds ratio for patients with CVD was 1.38 (95% CI: 0.97-1.98), HTN 1.13 (95% CI: 0.80-1.6), DM 1.78 (95% CI: 1.26-2.51) in age group 70-79 years 3.2 (95% CI: 2.1-4.87) and in age ⩾80 years 6.98 (95% CI: 4.02-12.11) compared with age group 60-69 years old, respectively. CONCLUSION: We did not find significant independent association between use of multiple medications and CKD. The switchover of odds for multiple medication suggested a confounding effect of covariates; further prospective studies are required to find the individualized effect of multiple medications on CKD.