Prevalence and factors associated with polypharmacy in Victorian adults with intellectual disability

Although polypharmacy is a medication safety concern leading to increased risk of non-adherence, adverse drug reaction and drug-drug interactions, polypharmacy and associated risk factors has rarely been investigated involving people with ID at a population level. The purpose of this paper is to analyze the prevalence of polypharmacy and to evaluate the role of different factors associated with polypharmacy in a state-wide representative population of adults with ID. In a population-based survey in Victoria, Australia, 897 people with ID 18 years of age or older were selected by simple random sampling. The data were collected from proxy respondents on behalf of people with ID. Polypharmacy was defined as the concomitant use of five or more medications. The data were weighted to reflect the age/sex/geographic distribution of the population. Results revealed that more than 76% of adults with ID had used prescribed medicine and about 21% were exposed to polypharmacy in the last two weeks. In both univariate and multivariate analyses, polypharmacy was significantly associated with older age, unemployment and inability to get help from family and friends if needed. After controlling for age, sex and severity of intellectual disability, polypharmacy was associated with having a blood pressure, blood cholesterol and blood glucose level check. Polypharmacy was also associated with a greater number of visits to general practitioners, fair or poor reported health status and inability to walk unaided. Subjects with epilepsy, diabetes, stroke, osteoporosis and cancer had a higher probability of polypharmacy. None of the disease inducing behaviors was associated with polypharmacy. This study highlights the need that medication should be regularly reviewed overall in ID population and particularly when polypharmacy exists.