Postmarketing surveillance of the safety of cimetidine: 10 year mortality report.

A total of 9928 cimetidine users were identified from prescriptions in four centres and followed for 10 years. The 'all-cause' mortality ratio fell from 1.9 in year 1 to 1.0 in years 8 to 10. Most of the early excess in mortality was attributable to cimetidine being given in the late stages of many diseases, often to counter adverse gastric effects of other drugs. Specific causes of mortality during years 5-10 of the study, were generally unremarkable. Significant increases in mortality ratios were apparent, however, for oesophageal cancer (years 5-7, 2.3; years 8-10, 1.9); lung cancer (years 5-7, 1.1; years 8-10, 1.7); diseases of the oesophagus, stomach, and duodenum (years 5-7, 3.3; years 8-10, 2.3); and chronic liver disease (years 5-7, 2.4; years 8-10, 3.3). None of these increases in mortality seems to be attributable to an adverse effect of cimetidine use. Data are also presented for mortality from diseases of the nervous system. Eight deaths (of which one was miscoded) were certified as being from motor neurone disease, representing a mortality ratio of 2.6 for years 2-10 of the study which is of borderline statistical significance. This study confirms that cimetidine is safe. Mortality from some diseases increased over the study period, but selection rather than any adverse effect of the drug is likely to be the explanation.