Effects of medication assessment as part of a comprehensive geriatric assessment on drug use over a 1-year period: a population-based intervention study.

High drug consumption among the elderly and inappropriate prescribing practices increase the risk of adverse drug effects in this population. This risk may be decreased by conducting, for example, a medication review alone or as part of a comprehensive geriatric assessment (CGA); however, little is known about the fate of the changes in medication made as a result of the CGA or medication review. To study the performance of the CGA with regards to medication changes and to determine the persistence of these changes over a 1-year period. This study was a population-based intervention study. A random sample of 1000 elderly (age > or =75 years) was randomized either to a CGA group or to a control group. Home-dwelling patients from these groups (n = 331 and n = 313 for intervention and control groups, respectively) were analysed in this study. Study nurses collected information on medication at study entry and 1 year later in both groups; in the intervention group, study physicians assessed, and changed when appropriate, the medication at study entry. The medication changes and their persistence over 1 year were then evaluated. Medication changes were more frequent in the intervention group than in the control group. Regular medication was changed during follow-up in 277 (83.7%) and in 228 (72.8%) [odds ratio (OR) 1.9; 95% CI 1.3, 2.8] patients in the intervention and control groups, respectively. In the intervention group, study physicians were responsible for 35.4% of all new prescriptions and for 15.6% of all drug terminations. Changes took place particularly in the prescription of CNS drugs. About 58% of the drugs initiated by study physicians were still in use 1 year later, and 25.5% of those terminated by study physicians had been reintroduced. Drug intervention as part of a CGA can be used to rationalize the drug therapy of a patient. However, its effectiveness is subsequently partly counteracted by other physicians working in the healthcare system.