Prescribing differences among older adults with differing health cover and socioeconomic status: a cohort study

Abstract Introduction Ireland currently has a mixed public-private health system, where about 40% of individuals are entitled to free or low-cost public care based on their income and age (1). As health reforms move Ireland toward universal healthcare, it is important to understand divergent prescribing practice to patients with differing health cover and socioeconomic status. Aim To determine how prescribing patterns for patients aged ≥65 years in primary care in Ireland differ between public and private patients. Methods Data were collected during a larger study from 44 general practices in Ireland (2). Data were extracted from the patient management system relating to demographics and prescribing. Patients were included in the present analysis if they had prescriptions issued on at least two dates during the study period (2011-2018), and had demographics (age and sex) and prescription dates recorded. The cohort was divided between those with public health cover (via the GMS scheme, which over-represents socioeconomically deprived people) and those without. We calculated the standardised rate of prescribing for drug classes separately for GMS and non-GMS (private) patients. We pre-specified 12 drug classes of specific interest, due to their prevalence, inclusion in Ireland’s Preferred Drugs Initiative, or potential for sub-optimal prescribing. We also analysed the number of medications, polypharmacy, and trends over time between groups, using multilevel linear regression adjusting for age and sex. Results The study included 42,456 individuals, 62% with GMS cover. The rate of prescribing for all pre-specified drug classes was higher for GMS patients compared to non-GMS patients. In all cases, the rate of prescribing was at least 1.6 times higher in the public group, with this being the minimum difference between groups in the rate of antibacterials for systemic use. We saw the greatest disparity in inhaled adrenergics combined with corticosteroids and/or anticholinergics where the rate of public prescribing was 2.25 times higher. The mean number of unique medications prescribed to GMS patients was 10.9 (SD 5.9), and 8.1 (SD 5.8) for non-GMS patients. Among GMS patients, 85% had polypharmacy (being on ≥5 medications) compared to 77% among the non-GMS patients, while 51% and 43% respectively had major polypharmacy (≥10 medications). The mean number of medications prescribed per person increased in both groups over time. The increase was steeper and more sustained in the public health cover group where the mean number of medications prescribed increased by 0.67 medications/year for GMS patients. The rate of increase was 0.13 (95%CI 0.13, 0.14) medications/year lower for non-GMS patients, a statistically significant difference. Conclusion Our study found a significantly larger number of unique medicines were prescribed to patients with public health cover, compared to those without. This disparity increased over time and was consistent within all drug classes analysed. This may be driven by socioeconomic deprivation rather than health cover, although a limitation is that we were unable to examine or adjust for these potential contributors separately. Our study provides new evidence that the growth in medication burden and polypharmacy among older adults is accelerated for those of lower socioeconomic status. References (1) Thomson S, Jowett M, Mladovsky P. The editors Observatory Studies Series No. 33 33 Observatory Studies Series Health system responses to financial pressures in Ireland. (2) Pérez T, Moriarty F, Wallace E, McDowell R, Redmond P, Fahey T. Prevalence of potentially inappropriate prescribing in older people in primary care and its association with hospital admission: Longitudinal study. BMJ. 2018;363.