The AdHOC Study of older adults' adherence to medication in 11 countries

Authors investigated, cross-nationally, the factors, including demographic, psychiatric (including cognitive), physical, and behavioral, determining whether older people take their prescribed medication. Older adults are prescribed more medication than any other group, and poor adherence is a common reason for non-response to medication.

Researchers interviewed 3,881 people over age 65 who receive home care services in 11 countries, administering a structured interview in participants' homes. The main outcome measure was the percentage of participants not adherent to medication.

In all, 12.5% of people (N=456) reported that they were not fully adherent to medication. Non-adherence was predicted by problem drinking (OR=3.6), not having a doctor review their medication (OR=3.3), greater cognitive impairment (OR=1.4 for every one-point increase in impairment), good physical health (OR=1.2), resisting care (OR=2.1), being unmarried (OR=2.3), and living in the Czech Republic (OR=4.7) or Germany (OR=1.4).

People who screen positive for problem drinking and who have dementia (often undiagnosed) are less likely to adhere to medication. Therefore, doctors should consider dementia and problem drinking when prescribing for older adults. Interventions to improve adherence in older adults might be more effective if targeted at these groups. It is possible that medication-review enhances adherence by improving the doctor-patient relationship or by emphasizing the need for medications.