[Differences in the relative incidence of adverse drug reactions in relation to age? An evaluation of the spontaneous reporting system of SANZ (Swiss Drug Monitoring Center)].

The risk of presenting adverse drug reactions (ADR) is greater for elderly patients. Chronological age is not an independent risk factor for ADRs, but age-dependent factors such as polymedication, multiple diseases and changes in pharmacokinetics and pharmacodynamics seem to be responsible for the risk of developing more adverse drug reactions. We analyzed the ADRs spontaneously reported to the Swiss Drug Monitoring Centre (SANZ) between 1981 and 1995. Age-specific relative incidences of the reported ADRs affecting different organ systems were calculated. For elderly patients we found a decrease in the relative incidence of dermatological ADRs and an increase in neuropsychic and hematological ADRs. The incidence of serious ADRs increased by 8.7% in older patients (> 70 years). The results of this analysis of spontaneous reports were inconsistent with results from epidemiological studies. The possibility and reasons for under-reporting ADRs occurring in elderly patients are discussed.