Mortality study of 18 000 patients treated with omeprazole

Background: The long term safety of potent gastric acid suppressive therapy has yet to be established. Method: General practice record review at a median interval of 26 months followed by retrieval of details of all deaths within four years using the UK National Health Service Central Registers in 17 936 patients prescribed omeprazole in 1993 - 1995. Death rates were compared with general population rates. Results: Records of 17 489 patients (97.5%) were examined. A total of 12 703 patients received further scripts for antisecretory drugs, 8097 for omeprazole only (65.6%): 3097 patients have died. All cause mortality was higher in the first year (observed/expected (O/E) 1.44 (95% confidence intervals (CI) 1.34 - 1.55); p< 0.0001) but had fallen to population expectation by the fourth year. There were significant mortality increases in the first year, falling to or below population expectation by the fourth year, for deaths ascribed to neoplasms (1.82 ( 95% CI 1.58 - 2.08); p< 0.0001), circulatory diseases (1.27 (95% CI 1.13 - 1.43); p< 0.0001), and respiratory diseases (1.37 ( 95% CI 1.12 - 1.64); p< 0.001). Increased mortality ascribed to digestive diseases (2.56 ( 95% CI 1.87 - 3.43); p< 0.0001) persisted, although reduced. Increased mortality rates for cancers of the stomach (4.06 ( 95% CI 2.60 - 6.04); p< 0.0001), colon and rectum (1.40 ( 95% CI 0.84 - 2.18); p = 0.075), and trachea, bronchus, and lung ( 1.64 ( 95% CI 1.19 - 2.19); p< 0.01) seen in the first year had disappeared by the fourth year but that for cancer of the oesophagus had not (O/E 7.35 ( 95% CI 5.20 - 10.09) ( p< 0.0001) in year 1; 2.88 ( 95% CI 1.62 - 4.79) ( p< 0.001) in year 4). Forty of 78 patients dying of oesophageal cancer had the disease present at registration. Twenty seven of those remaining cases had clinical evidence of Barrett's disease, stricture, ulcer, or oesophagitis at registration (O/E 3.30 ( 95% CI 2.17 - 4.80)). Six deaths occurred in patients with hiatal hernia or reflux only ( O/E 1.02 ( 95% CI 0.37 - 2.22)) and five in patients without oesophageal disease (O/E 0.77 ( 95% CI 0.25 - 1.80)). No relationships were detected with numbers of omeprazole scripts received. Conclusions: Increases in mortality associated with treatment are due to pre-existing illness, including pre-existing severe oesophageal disease. There was no evidence of an increased risk of oesophageal adenocarcinoma in those without oesophageal mucosal damage recorded at registration.