The influence of educational level on polypharmacy and inappropriate drug use: a register-based study of more than 600,000 older people.

OBJECTIVES: To investigate whether low educational attainment is associated with polypharmacy and potential inappropriate drug use (IDU) in older people.

DESIGN: Cross-sectional register-based study.

SETTING: Sweden.

PARTICIPANTS: Older people aged 75 to 89 who, filled at least one drug prescription between August and October 2005 and, consequently, were listed in the Swedish Prescribed Drug Register (SPDR) (N=626,258). Data were obtained from the SPDR, the inpatient register, and the education register.

MEASUREMENTS: The main outcome measures were polypharmacy (concurrent use of > or =5 drugs), excessive polypharmacy (concurrent use of > or =10 drugs), and potential IDU. Four quality indicators developed by the Swedish National Board of Health and Welfare were used for the assessment of potential IDU: concurrent use of three or more psychotropic drugs, prescription of long-acting benzodiazepines, prescription of anticholinergics, and at least one clinically relevant potential drug-drug interaction (DDI). Comorbidity was measured using the Charlson Comorbidity Index.

RESULTS: Subjects with low education had a higher probability of polypharmacy (odds ratio (OR)=1.11, 95% confidence interval (CI)=1.10-1.12), excessive polypharmacy (OR=1.15, 95% CI=1.13-1.17), and potential IDU (OR=1.09, 95% CI=1.07-1.17), after adjustment for age, sex, comorbidity, and type of residential area (urban or rural). Decreasing educational attainment was associated with a higher probability of using three or more psychotropic drugs and potential DDIs, whereas the opposite association was observed for anticholinergic drugs. Long-acting benzodiazepines showed no association. Elderly women with low education were slightly more likely to have polypharmacy, excessive polypharmacy, and potential IDU than men with low education. Overall, the ORs were modest and statistically significant because of the large sample size.

CONCLUSION: Low educational attainment was associated with a greater likelihood of poypharmacy, excessive polypharmacy, and potential IDU in elderly Swedish persons, even after controlling for age, sex, place of residence, and comorbidity. Women with low education had slightly higher likelihood of receiving polypharmacy and potential IDU than men with low education. The recently established SPDR may be useful for continuous monitoring and for designing interventions to improve drug quality in low-educated elderly people.