Drug safety surveillance strongly depends on the spontaneous and voluntary reporting of adverse drug reactions (ADR). A major limiting factor of spontaneous reporting systems is underreporting (UR) which describes incorrectly low reporting rates of ADR. Factors contributing to UR are numerous and feature country-dependent differences.

Understanding causes of UR is necessary to facilitate targeted interventions to improve ADR reporting and pharmacovigilance.

A cross-sectional questionnaire-based telephone survey was performed among physicians in outpatient care in a federal state of Germany.

From n=316 eligible physicians n=176 completed the questionnaire (response rate=55.7%). Most of the physicians (n=137/77.8%) stated that they report ADR, which they have observed to the competent authority rarely (n=59/33.5%), very rarely (n=59/33.5%) or never (n=19/10.8%); the majority (n=123/69.9%) had not reported any ADR in 2014. Frequent subjective reasons for ADR non-reporting were (specified response options): lack of time (n=52/29.5%), the subjective evaluation that the required process of reporting is complicated (n=47/26.7%) or requires too much time (n=25/14.2%) or the assessment that reporting of an ADR is needless (n=22/12.5%); within free answers the participants frequently stated that they do not report ADR that are already known (n=72/40.9%) and they only report severe ADR (n=46/26.1%).

Our results suggest a need of interventions to inform physicians about pharmacovigilance and to modify the required procedure of ADR reporting or to offer other reporting options.