Socioeconomic differences in drug use among older people : trends, polypharmacy, quality and new drugs

Abstract

Polypharmacy and potentially inappropriate drug use (IDU) is a major patient safety and public health concern in the elderly, resulting in an increased likelihood of adverse drug reactions, drug-drug interactions (DDI), hospitalization, poor quality of life and mortality.

This doctoral thesis investigated the complex relationship between drug use and socioeconomic position (SEP) and characterized the drug use, quality of prescribing, development of drug use over time, and use of new drugs in the elderly. The data were derived from the Swedish Panel Study of the Living Conditions of the Oldest Old (SWEOLD) project (Studies I and II) and from the Swedish Prescribed Drug Register (SPDR), National Inpatient Register and Education Register (Studies III and IV). The SWEOLD Project is a national representative, community-based study on living conditions of people aged >=77 years in Sweden. The SPDR is a new health register which contains data on all dispensed prescriptions to the entire Swedish population. The major findings are summarized below.

Study I. The relationship between drug use and SEP (measured by education, occupation, or income), was investigated using SWEOLD 2002 survey data. Polypharmacy (use of five or more drugs) was observed in 42% of the elderly. Low education was associated with polypharmacy (OR = 1.46, 95% CI, 1.02-2.07), after controlling for age and sex. The tendency for an association between low education and polypharmacy remained (OR = 1.40, 95% CI 0.96-2.05), however not conclusive, after adjustment for age, sex, comorbidity, and marital status. We did not observe any association between occupation or income and polypharmacy.

Study II. Changes in drug use between educational groups during one decade were based on comparison of the two SWEOLD surveys (1992 and 2002). Overall drug use and mean number of drugs used per person increased between the years. The prevalence of polypharmacy increased more than twofold (from 18% in 1992 to 42% in 2002). In both SWEOLD surveys, the less educated reported polypharmacy more often (19% in 1992 and 46% in 2002) than the higher educated (12% in 1992 and 36% in 2002). Potential DDI also increased, both among the less educated (14% in 1992 to 26% in 2002) and the higher educated (18% in 1992 to 24% in 2002). These changes were most prominent among low educated women.

Study III. The association of polypharmacy with education was verified using the nationwide SPDR. In addition, relationship between excessive polypharmacy, potential IDU and educational level was investigated. The low educated had a higher probability of polypharmacy (OR: 1.11, 95% CI: 1.10-1.12), excessive polypharmacy (OR: 1.15, 95% CI: 1.13-1.17) and IDU (OR: 1.09, 95% CI: 1.09-1.17), after adjustment for age, sex, comorbidity and type of residential area (urban/rural). Low educated elderly women were slightly more likely to have polypharmacy and excessive polypharmacy and IDU than low educated men.

Study IV. The association between educational level and use of newly marketed drugs (NMD) was investigated. Use of NMD was associated with low education (OR: 0.82; 95% CI: 0.80 0.88 for <9 compared with >=13 years of education), after adjustment for age, sex, type of residential area, and number of dispensed drugs. Decreasing educational attainment was associated with a lower probability of using most of the NMD, especially oseltamivir and ezetimibe.

Conclusions: Low socioeconomic position increases the risk of drug use, polypharmacy, excessive polypharmacy, potential IDU, and potential DDI. Polypharmacy, potential DDI, and most kinds of drugs usage have increased within a decade. Although low educated elderly have a higher drug use than high educated, the low educated use new drugs to lesser extent. Today, the main focus of medication safety programs is on clinical aspects. Future programs of rational drug therapy should also involve socioeconomic aspects surrounding drug use. This study shows that inequalities in drug use may exist even in a health care system that claims to ensure a high degree of equity.