Analysis of factors of importance for drug use

Background: There are differences in drug use depending on non-medical factors such as age, gender and socioeconomic status. The combined effect of these factors, with adjustment for multimorbidity, is highly relevant to study to ensure equality in drug use. Objectives: 1. To examine drug use related to age, gender, income and education after adjustment for multimorbidity, in an entire adult population and in a population where prescription drugs were issued only by general practitioners. 2. To analyse if gender-related morbidity explains the differences in drug use. 3. To examine to what extent the elderly may lack indication for treatment. Methods: Register-based methods were applied in all papers, using data from Östergötland County. To estimate multimorbidity the ACG-Case Mix was used in all papers. Drug use depending on age, gender, income- and educational level, after adjustment for multimorbidity, was analysed in the entire adult population in Paper I, and in the primary healthcare population in Paper III. In Paper II diseases tending to afflict females more frequently were identified, together with the prescription drugs used to treat these diseases. Drug use was analysed before and after exclusion of these identified prescription drugs. In Paper IV the proportion of patients 65 years or older having indication for a number of their prescription drugs, identified as inappropriate for elderly, was examined, with further analysis of what may affect the result. Results: Significant differences in drug use were identified depending on age, gender, income and education, despite adjustment for multimorbidity. The elderly, females and individuals with the lowest levels of income and education had higher drug use. The differences persisted when drug use in primary healthcare was examined. The gender difference in drug use decreased when prescription drugs used to treat diseases afflicting females more often were excluded from the analyses. Less than half of the patients’ prescription drugs (45.1%), studied in Paper IV had indication for treatment. The oldest patients had to the lowest extent indication for treatment. Conclusion: The patients’ age, gender, income and education affect the drug use, despite adjustment for multimorbidity. Gender-related morbidity seems to explain some of the gender difference in drug use, and lack of indication for treatment among the elderly explains some of the age difference