High concomitant use of interacting drugs and low use of gastroprotective drugs among NSAID users in an unselected elderly population: a nationwide register-based study.

backgroundNSAIDs are commonly used in the elderly and carry significant risks of adverse events when used concomitantly with potentially interacting drugs.

objectiveThe aim of this study was to provide a valid estimate of concomitant use of potentially interacting drugs and gastroprotective agents among elderly NSAID users.

methodsThis was a nationwide Swedish register-based study of drug prescriptions for 1 529 267 persons aged ≥65 years in 2008, using the Swedish Prescribed Drug Register. The proportions of concomitant use of potentially interacting drugs and gastroprotective agents were analysed among NSAID users, categorized by age group, sex and NSAID use, defined as: non-users, people with 0-30 days of treatment, people with >30-180 days of treatment and people with >180 days of treatment. Use of the following concomitant drugs was evaluated: potentially harmful interacting drugs, i.e. antithrombotic drugs, antihypertensive drugs or drugs for congestive heart failure (digitalis glycosides, thiazide diuretics, loop diuretics, β-adrenoceptor antagonists, calcium channel antagonists, ACE inhibitors and angiotensin II type 1 receptor antagonists [angiotensin receptor blockers]) and other drugs (systemic corticosteroids, selective serotonin reuptake inhibitors [SSRIs], methotrexate and lithium); and gastroprotective drugs.

resultsIn the study cohort, 257 963 (16.9%) people had collected at least one prescription for an NSAID in 2008. This use was higher in females than in males and decreased in older age groups in both sexes. In the age groups 65-69, 70-74, 75-79, 80-84 and ≥85 years, the frequencies of NSAID users were 20.6%, 20.5%, 18.9%, 15.6% and 11.6% among women, and 16.8%, 16.7%, 15.2%, 13.5% and 11.1% among men, respectively. NSAID users often concomitantly used potentially interacting drugs, e.g. over 30% used antithrombotic agents, and women had higher concomitant use of SSRIs, i.e. 12% compared with 6% in men in the youngest age group. Concomitant use of potentially harmful interacting drugs generally increased with age and with increasing use of NSAIDs. Among the eldest (age ≥85 years), concomitant drug use was stable over NSAID groups. Only 40% of regular NSAID users (i.e. those prescribed NSAIDs for >180 days) were prescribed any gastroprotective medication.

conclusionsPrescribers should be alert to the possibility of potentially harmful interactions between NSAIDs and commonly prescribed drugs in the elderly. Increased use of gastroprotective medication might be justified in this context.