Factors associated with the use of dietary supplements and over-the-counter medications in Japanese elderly patients

BACKGROUND: The use of dietary supplements and over-the-counter (OTC) drugs is increasing, and there is adequate concern about potential harmful effects. However, there are limited reports on the concurrent use of nonprescription medications with prescription medications in elderly patients. Therefore, this study was conducted to describe the use of dietary supplements and OTC drugs, and to identify predictors for their use in elderly patients using medications prescribed for chronic diseases. METHODS: This was a cross-sectional study that enrolled 729 patients aged ≥65 years with chronic diseases, between January and March 2016. Data regarding socio-demographic status, medical condition, number of prescriptions, use of nonprescription medications, and psychological status were collected using a self-administered questionnaire and by review of medical records. Data regarding use of dietary supplements and OTC drugs were analyzed using descriptive statistics. Logistic regression analysis was applied to investigate factors associated with the use of dietary supplements and OTC drugs. RESULTS: The regular use of nonprescription drugs was reported by 32.5% of patients. Vitamins were the most commonly used dietary supplements in elderly patients. Female sex, higher educational qualifications, and good economic status were identified as predictors for the use of nonprescription medications. Concurrent use of nonprescription medications with more than 5 prescription medications was detected in 12.2% of participants. The disclosure rate of the use of nonprescription medications by patients to the physician was 30.3%. CONCLUSION: The use of dietary supplements and OTC drugs was common in elderly patients with chronic diseases, and its use is associated with sex, education, and economic status. General practitioners (GPs) need to recognize the potential use of nonprescription medications, considering that polypharmacy was common and disclosure rate was low in this study. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12875-017-0699-9) contains supplementary material, which is available to authorized users.