Effects of age on reporting of adverse clinical events: results from two postmarketing surveillance methods

Two postmarketing surveillance methods were employed to determine the possible effects of age on reports by outpatients of adverse clinical events (ACEs) occurring shortly after treatment with targeted oral antibiotics or tricyclic antidepressants. One approach involved staff-initiated interviews of patients by telephone and the other involved patient-initiated telephone calls to report possible adverse drug reactions. Regardless of the method, the interviews obtained ACE reports both spontaneously and by review of organ systems. Both postmarketing methods confirmed monotonic relationships for age with treatment duration on the target drugs and with the number of concurrent medications. However, the expected positive correlation between age and spontaneously reported ACEs was evident only in the self-monitoring patients who initiated reports. Negative correlations between age and the number of reported valid ACEs were seen in six independent samples, whereas only two demonstrated a positive relationship. This disparity may elucidate a critical methodologic problem: careful attention must be paid to the means of eliciting information about possible adverse clinical events before attempting to study adverse drug reactions, which are necessarily a subset of ACEs.