Aims In post-marketing setting, spontaneous reporting by physicians is
a mode of surveillance of adverse effects associated with drug use. T
he objective of this study was to quantitatively assess under-reportin
g of adverse drug reactions (ADRs) in general practice. Methods A rand
om sample of 100 general practitioners (GPs) practising in the region
of the Bordeaux pharmacovigilance centre were surveyed to obtain data
on adverse effects observed. Overall, 81 GPs agreed to record during 3
non-consecutive working days any effect they believed to be associate
d with drug use. The types of effects, regardless of their seriousness
and labelling, and the drugs suspected were characterized and compare
d to spontaneous reports received from GPs by the Bordeaux pharmacovig
ilance centre during the reference period.Results The average number o
f ADRs observed per day per GP was 1.99. The estimate of the under-rep
orting coefficient (U) was 24 433 (95% confidence interval: 20 702-28
837) which indicates that, as a whole, GPs might be expected to report
only 1 out of every 24 433 ADRs to the pharmacovigilance centre. Unde
r-reporting was lowest for serious and unlabelled effects (U=4610; 95%
CI: 2514-8454) and for drugs marketed recently (U=12 802; 95% CI: 817
4-20 050). Conclusions Adverse effects due to drugs are part of GPs ro
utine activities. According to the observed trend in under-reporting,
there appears to be a selection process which indicates that spontaneo
us reporting in general practice is not conducive to an exhaustive des
cription of the safety profile of a drug. However, our findings are co
nsistent with greater efficacy of spontaneous reporting in detecting s
erious and unlabelled effect.