Mortality study of 18 000 patients treated with omeprazole

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Mortality in omeprazole takers

Table 1 Major diagnostic groups of patients prescribed omeprazole

Diagnostic figures add up to more than 100% because some patients had more than one diagnosis.

*A single script is equivalent to one month of treatment at a standard dosage.

Records of patients registered were re-examined after two
years, and new diagnoses of oesophageal cancer at hospital
attendance and details of subsequent omeprazole and other
antisecretory drug prescribing were recorded. Patients trans-
ferring to another general practitioner were followed by post
or visit to the practice if nearby. The records of cohort
members were also flagged at the National Health Service
Central Register (NHSCR) in England and Scotland, providing
data on all causes of death and confirmation of cancer
diagnoses.

Observed death rates, classified according to the ninth revis-
ion of the International Classification of Disease (ICD), were
compared with expected population rates in England and
Scotland using published data from the Office of National
Statistics. For this purpose, rates were based on those
individuals dying in 1996, the approximate midpoint of the
study period, taking account of age, within five year groups,
and sex. In addition, death rates were examined in relation to
the number of scripts received by patients for omeprazole, as
noted at the time of registration. Relative risks presented are
the ratios of observed to expected deaths, together with their
95% confidence intervals (CI) throughout, alongside the
observed and expected numbers of deaths.

The study was approved by local ethics committees and by
the Office of National Statistics. It was also constructed to
conform to the guidelines for safety assessment of marketed
medicines (SAMM guidelines),⁷ and was registered with the
Medicines Control Agency of the UK.

RESULTS

A total of 17 936 patients had been registered by December
1995 when entry was completed, and clinical follow up data
were available after two years in 17 489 (97.5%) patients.
Mean age of the patients at registration was 59.6 years
(median 61.5; range 7-105) with 46.9% being men. In the
year prior to registration, 38% had received 1-2 omeprazole
prescriptions while 25% had received six or more. Table 1
shows the major diagnostic groupings in patients prescribed
omeprazole. Oesophageal disease and gastrointestinal symp-
toms of uncertain cause formed the bulk of the indications.
There were 12 501 diagnoses of oesophageal disease recorded.
Oesophagitis (3664), reflux not otherwise specified (3842),
and hiatal hernia (3142) were the commonest recorded but
with substantial numbers of patients with stricture (791),
ulcer (441), or Barrett’s disease (417) of the oesophagus.
Oesophageal disease was pre-existing cancer in 40 and was
not clearly specified in the remaining 164.

We found that 2096 patients (11.7%) had undergone a total
of 2477 upper abdominal procedures in the past. Commoner
procedures were cholecystectomy (1014 (5.3%)), oesophageal
surgery (489 (2.7%)) and elective ulcer surgery (439 (2.4%)).
Further prescriptions for antisecretory treatments had been
received by 12 703 (72.6%) of 17 489 patients with two year
follow up data; 10 929 (62.5%) had received at least one
further prescription for omeprazole with 8097 having omepra-
zole alone.

Table 2 shows that observed mortality tended to be higher in
the first year after registration and then fell overall to population

*Expected deaths based on national (England and Wales) rates for 1996, except for Glasgow which is based on Scottish rates for 1996, and total rates
which are based on pooled Scotland, England, and Wales expected deaths. Calculations made for each sex separately within five year age groupings.

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