Association between socioeconomic status and medication-related harm in elderly patients: a multicentre prospective cohort study in England

Introduction Older adults are at high risk of medication-related harm (MRH)[1]. Lower socioeconomic status (SES) is associated with polypharmacy and inappropriate medication use [2]. Our study investigated the relationship between SES and MRH in older adults. Methods Methods for this study are published.[3] Patients aged 65+ years were recruited at hospital discharge from 5 teaching hospitals in England between 2013 and 2015. Patients were followed up for 8-weeks by senior pharmacists to identify MRH using 3 data sources: hospital readmissions, GP records and patient interviews. Based on residential postcodes, Index of Multiple Deprivation quintiles[4] were used as a standard proxy measure for patient SES (1 least deprived, 5 most deprived). Logistic regression models, adjusting for confounders (age, gender, number of medicines, Charlson index, Barthel index), were used to examine the association between SES and MRH. Results 1116 patients (median age 82; 58% female) were included. 413 patients experienced MRH, of which 301 (73%) experienced MRH from adverse drug reactions, 45 (11%) from non-adherence, and 67 (16%) from combinations of these and medication errors. In the univariate analysis, lower SES was significantly associated with MRH due to non-adherence (OR=1.27, 95% CI=1.08-1.49, p=0.004). Multivariable logistic regression, controlling for confounders, found this relationship to remain significant (OR=1.39, 95% CI=1.07-1.82, p=0.015). There was no association between lower SES and adverse drug reactions (OR 0.92, 95% CI=0.84-1.01, p=0.092). Key Conclusions Lower SES is independently associated with MRH due to non-adherence, but not ADR. This association might be mediated by lower health literacy in patients with low SES.