Predictive factors of self-medicated analgesic use in Spanish adults: a cross-sectional national study

Background: Analgesics are among the most commonly consumed drugs by the world populations. Within the broader context of self-medication, pain relief occupies a prominent position. Our study was to ascertain the prevalence of self-medication with analgesics among the Spanish population and to identify predictors of self-medication, including psychological disorders, psychological dysfunction, mental health status, and sociodemographic and health-related variables. Methods: We used individualized secondary data retrieved from the 2009 European Health Interview Survey (EHIS) for Spain to conduct a nationwide, descriptive, cross-sectional pharmacoepidemiology study on self-medication with analgesics among adults (individuals aged at least 16 years) of both genders living in Spain. A total of 7,606 interviews were analysed. The dichotomous dependent variables chosen were the answers "yes" or "no" to the question In the last 2 weeks have you taken the medicines not prescribed for you by a doctor for joint pain, headache, or low back pain?" Independent variables were sociodemographic, comorbidity, and healthcare resources. Results: A total of 7,606 individuals reported pain in any of the locations (23.7%). In addition, analgesic consumption was self-prescribed in 23.7% (1,481) of these subjects. Forty percent (40.1%) of patients self-medicated for headache, 15.1% for low back pain, and 6.7% for joint pain. The variables significantly associated with a greater likelihood of self-medication of analgesics, independently of pain location were: age 16-39 years (2.36 < AOR < 3.68), higher educational level (1.80 < AOR < 2.21), psychological disorders (1.56 < AOR < 1.98), and excellent/good perception of health status (1.74 < AOR < 2.68). In subjects suffering headache, self-prescription was associated with male gender (AOR 2.13) and absence of other comorbid condition (AOR 4.65). Conclusions: This pharmacoepidemiology study constitutes an adequate approach to analgesic self-medication use in the Spanish population, based on a representative nationwide sample. Self-prescribed analgesic consumption was higher in young people with higher educational level, higher income, smoker, and with psychological disorders and with a good perception of their health status independently of the location of pain.