Geographical variation in adverse event reporting rates in clinical trials.

A group of 13,698 patients from 127 gastro-intestinal clinical trials, conducted in 13 countries was included in the analyses. All adverse events reported were included in the evaluation. The general adverse event reporting rate, the mean number of adverse events reported, the serious adverse event reporting rate and the mean number of serious adverse events reported were calculated for each country. In addition, the pattern of adverse events reported in each country was studied. The general adverse event reporting rate varied between 17% and 68% with a mean of 47% and the serious adverse event reporting rate varied between 1% and 20% with a mean of 8%. The mean number of adverse events, reported by patients reporting adverse events, varied between 1.5 and 2.7 with a mean of 2.1 and the mean number of serious adverse events, reported by patients reporting serious adverse events, varied between 1.1 and 1.7 with a mean of 1.4. In addition to these differences, patients/investigators had a tendency to put emphasis on different kinds of adverse events in different countries.

Safety experience from long-term treatment with omeprazole.

Omeprazole was administered for up to 6 years in 859 patients for 'prevention of relapse in patients with poorly responsive peptic ulcer or reflux oesophagitis'. The pattern of adverse events reported during long-term treatment was similar to the adverse-event profile in short-term treatment with omeprazole (n = 2,818), ranitidine (n = 1,572) and cimetidine (n = 891). Omeprazole had essentially the same adverse-event profile as the two H2-receptor antagonists. The adverse-event profile for omeprazole during long-term treatment did not differ from that seen during short-term treatment with either omeprazole or the H2-receptor antagonists. The rate of occurrence of any specific adverse event decreased with time, and no previously unidentified adverse event occurred with long-term omeprazole therapy. There were no serious adverse events that were considered to be causally related to omeprazole therapy. Thus, omeprazole has been shown to be well tolerated in both short- and long-term treatment.