Mortality study of 18 000 patients treated with omeprazole

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Bateman, Colin-Jones, Hartz, et al

Table 3 Observed and expected number of deaths for individual ICD (International Classification of Disease) chapters

Observed/expected (O/E) ratios in parentheses.
*O/E significantly >1.0, p<0.05.

expectation, with similar trends in the six conurbations. Table 3
shows the mortality observed for individual ICD chapters by
year, together with their associated relative risks (observed/
expected (O/E)). Mortality was initially higher than expected
for neoplasms (observed 217, expected 119; O/E 1.82; 95% CI
1.58-2.08; p<0.0001) and also for diseases of the circulatory
(observed 284, expected 224; O/E 1.27; 95% CI 1.13-1.43;
p<0.0001), respiratory (observed 112, expected 82; O/E 1.37;
95% CI 1.12-1.64; p<0.001), and digestive (observed 45,
expected 18; O/E 2.56; 95% CI 1.87-3.43; p<0.0001) systems.
Death rates from neoplasms fell to population expectation by
year 4, as did those for the circulatory and respiratory systems.
Greater mortality than expected was also initially recorded for
infectious and parasitic disease (O/E 3.09; 95% CI 1.33-6.08;
p<0.01), falling to population expectation by the fourth year of
the study. Initially increased mortality from musculoskeletal
disorders, upper gastrointestinal disorders, and chronic liver
disease, although falling with time towards population expecta-
tion, still tended to remain raised.

Table 4 shows the observed and expected deaths for selected
ICD rubrics, including major gut epithelial cancers and cancer
of the lung, breast, and blood forming tissues, ischaemic and
cerebrovascular disease, and upper gastrointestinal causes. For
all selected causes, initial increases in mortality declined
towards or below population expectation, except for oesopha-
geal cancer and liver disease which remained significantly
above expectation.

To examine results for oesophageal cancer in more detail, we
stratified data in those without oesophageal cancer at
registration according to whether patients were recorded ini-
tially as having Barrett’s disease, oesophageal ulcer, stricture,
or oesophagitis (categorised as severe disease), or whether
they had reflux or hiatal hernia without Barrett’s disease,
ulcer, stricture, or oesophagitis (categorised as mild disease).
Table 5 shows the types of non- malignant oesophageal disease
present in the 38 patients diagnosed as having oesophageal
cancer after registration. Among those with severe oesopha-
geal disease, 27 died of oesophageal cancer (expectation 8.2 in
four years; O/E 3.30; 95% CI 2.17-4.80). In contrast, of those
with mild oesophageal disease, evidenced by clinical diag-
noses of reflux or hiatal hernia, only six died of oesophageal
cancer (expectation 5.9; O/E 1.02; 95% CI 0.37-2.22). In those
without initial clinical diagnoses of oesophageal disease, five
patients died (against expectation 6.5; O/E 0.77; 95% CI 0.25-
1.80). Of the 417 who had Barrett’s disease identified at some
time and recorded at registration, nine had died of oesopha-
geal cancer (O/E 11.25; 95% CI 5.14-21.36).

In those with severe oesophageal disease, the risk of devel-
oping oesophageal cancer was slightly lower (observed 8,
expected 2.8; O/E 2.86; 95% CI 1.23-5.63) in those who had
received six or more scripts in the year before registration than
in those who had received fewer (observed 19, expected 5.2;
O/E 3.65; 95% CI 2.20-5.71). Examination of mortality from
all other neoplasms, and from all other (non-neoplastic)

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