Polypharmacy and psychotropic polypharmacy in adults with intellectual disability: a cross-sectional total population study.

BACKGROUND Adults with intellectual disability (ID) are prescribed high levels of medication, with polypharmacy and psychotropic polypharmacy common. However, reported rates vary between studies, and there has been an over-reliance on obtaining data from convenience samples. The objective of this study was to determine the prevalence of medication use and polypharmacy in a population-level sample of adults with IDs. Factors associated with polypharmacy and psychotropic polypharmacy are explored. METHODS We used a total population sample of 217 adults with IDs known to services in Jersey (sampling frame n = 285). The Anatomical Therapeutic Chemical classification system was used to categorise medications that participants were currently taking on a regular basis. We examined associations of polypharmacy and psychotropic polypharmacy with socio-economic status, health and demographic variables using univariate and multivariate analyses. RESULTS A total of 83.4% of participants were prescribed medication, with high doses common. Of the participants, 38.2% were exposed to polypharmacy while 23% of participants were exposed to psychotropic polypharmacy. After controlling for demographic, health and socio-economic characteristics, polypharmacy was significantly associated with older age, increased severity of ID, living in a residential setting and having increased comorbidities. Psychotropic polypharmacy was associated with being male, being aged 50+ years and having had a psychiatric diagnosis over the life course. Being prescribed psychotropic drugs above the defined daily dose was not associated with having had a psychiatric diagnosis over the life course, suggesting the possibility of 'off label' prescribing. CONCLUSIONS Our results indicate that medication use, in high doses, alongside polypharmacy and psychotropic polypharmacy are highly prevalent in adults with ID. The exposure to multiple medications increases the risk of developing adverse drug events, drug-drug interactions and medication-related problems. Future population-level, prospective cohort studies should examine the prevalence of polypharmacy and psychotropic polypharmacy using standardised definitions and consider the potential impact of adverse drug events, drug-drug interactions and medication-related problems in this population.