Abstract
Background: There is limited published evidence on the prevalence of potentially inappropriate prescribing of medicines in relation to kidney function in older Australians, particularly those with dementia. Objectives: To examine the prevalence, temporal trends and factors associated with potentially inappropriate prescribing of renally-dependent medicines in patients with dementia, using Australian general practice data. Methods: This comparative study was reported in accordance with the STROBE guidelines for cohort studies. Retrospective analyses of the National Prescribing Service (NPS) MedicineInsight dataset were performed to determine the proportion of patients aged ≥ 65 years with a recorded diagnosis of dementia, along with matched controls, who had potentially inappropriate prescribing based on their estimated glomerular filtration rate (eGFR) during the study period (2011-2020). Each patient was included only once throughout the study. Potentially inappropriate prescribing was evaluated for 33 commonly used medicines, using the Cockcroft-Gault equation for estimated creatinine clearance or eGFR, in accordance with the guidelines from the Australian Medicines Handbook (AMH). Each patient's medicines were included if they were prescribed within 180 days after the most recent recorded lowest eGFR value for the patient. Medicines having prescribed doses exceeding those recommended for an individual's renal function were classified as 'inappropriate dosage', while those whose use was advised against were labelled 'contraindicated'. Both categories were regarded as inappropriate prescriptions. Descriptive statistics were used to summarise patient characteristics and medication use. Temporal trends were displayed in graphs, with statistical significance determined using the Cochran-Armitage test. Binary logistic regression models were used to examine the associations between sociodemographic and clinical factors and the prescribing of medicines inconsistent with AMH guidelines. Results: The unmatched cohorts included 33,101 patients, comprising 4092 with dementia and 29,009 without. Among them, 58.4% were female, and the overall median age was 82 years [interquartile range (IQR): 77-87]. After propensity score matching, there were 4041 patients with dementia and 8031 without dementia. Over the study period, potentially inappropriate prescribing increased slightly, but insignificantly, in both groups of patients; the prevalence of inappropriate use of at least one of the 33 drugs of interest rose from 6.5% (95% CI 4.5-9.1%) in 2011 to 8.9% (95% CI 6.0-12.7%; p for trend: 0.966) in 2020 in the dementia group, and 9.2% (95% CI 8.0-10.5%) to 11.1% (95% CI 10.3-12.0%; p for trend: 0.224) in the matched controls. Over the ten-year period, approximately 9.3% (377) of patients with dementia in the matched cohort received at least one potentially inappropriate prescription. Among these, 154 (40.8%) were for contraindicated medicines, and 223 (59.1%) were for inappropriate doses based on renal function. Among patients with dementia in the matched cohort, fenofibrate, nitrofurantoin, and moxonidine were the most frequently prescribed medicines at doses inconsistent with AMH guidelines. In the unmatched dementia cohort, potentially inappropriate prescribing was not significantly associated with demographic characteristics or most comorbidities; however, it occurred more frequently in patients with an eGFR below 30 mL/min/1.73 m(2) or those with concomitant diabetes. Conclusions: Positively, the prevalence of potentially inappropriate prescribing of renally-dependent medicines in primary care patients with dementia in Australia was similar to their matched controls. However, there was room for improvement in the prescribing of these drugs in both patients with and without dementia.