Potentially inappropriate prescribing of renally cleared drugs in elderly patients in community and aged care settings.

Background: Limited data are available on the prevalence of inappropriate prescribing of renally cleared drugs in elderly patients in Australia.

Objectives: To quantify and compare the extent of inappropriate prescribing (defined as at least one drug prescribed in an excessive dose or when contraindicated with respect to renal function) of renally cleared drugs in elderly patients across the community and aged care settings, and to determine factors associated with patients being prescribed one or more potentially inappropriate renally cleared drugs.

Methods: This retrospective study examined de-identified Home Medicines Review (HMR) and Residential Medication Management Review (RMMR) cases pertaining to 30,898 patients aged 65 years and over. Only 25 % (n = 7625) of these patients had documented information on their renal function. Among them, 4035 patients were prescribed at least one of the 31 renally cleared drugs examined in this study. For these patients, details including demographics, medications, medical conditions and pathology test results were extracted. Creatinine clearance was estimated using the Cockcroft-Gault formula, and the prevalence of inappropriate prescribing of the 31 drugs was examined on the basis of conformity with the recommendations in the Australian Medicines Handbook. Multivariate logistic regression was performed to determine the factors associated with patients being prescribed one or more potentially inappropriate renally cleared drugs.

Results: The mean (± standard deviation) ages of the HMR patients (n = 3315; 59 % female) and RMMR patients (n = 720; 68 % female) were 78.3 ± 7.2 and 86 ± 7.3 years, respectively. Over one quarter of the patients (n = 1135 out of 4035; 28.1 %) prescribed the renally cleared drugs examined in this study had evidence of inappropriate prescribing of at least one of the drugs, with respect to their renal function. The drugs/drug classes most commonly prescribed inappropriately were perindopril, fenofibrate, glibenclamide, gliptins, metformin, olmesartan, bisphosphonates and strontium. The factors independently associated with patients being prescribed one or more potentially inappropriate renally cleared drugs were advancing age [odds ratio (OR) 1.06 per year increase, 95 % confidence interval (CI) 1.05-1.07; P < 0.001], the total number of renally cleared drugs prescribed (OR 1.44 per unit increase, 95 % CI 1.29-1.61; P < 0.001), presence of diabetes (OR 1.51, 95 % CI 1.30-1.76; P < 0.001), presence of heart failure (OR 1.38, 95 % CI 1.13-1.69; P < 0.005) and living in aged care facilities (OR 1.28, 95 % CI 1.06-1.5; P < 0.05).

Conclusion: Inappropriate prescribing of renally cleared drugs is common in older Australians. Intervention studies to improve prescribing of renally cleared drugs in the elderly appear to be warranted.