This is, to date, the largest study examining causes of mortality in patients with BO. All incident cases of BO within NI were identified during the study period. Emigration out of NI in people over 50 years is low, reducing problems associated with loss to follow up. Although long term follow up was not possible, the number of cases in this study (2373) far exceeds any of those carried out previously, with the total person years of follow up amounting to 7413 years. This and the population based nature of our study, which minimises selection biases, is likely to provide a robust estimate of mortality in patients with BO.
In accordance with the observations of other research groups,8,11,16
patients with BO had mortality rates similar to an age and sex matched control population. This conflicts with the findings of a smaller study by van der Burgh and colleagues9
who followed up 166 patients with BO over a mean period of 9.3 years (1440 person years). Differences in study design, in particular size and period of follow up, are likely to have resulted in this discrepant finding. It is also possible that mortality rates could have been underestimated in the current study, if some patients included in the cohort had a biopsy taken from an unrecognised hiatus hernia.
Oesophageal cancer accounted for only 4.7% of all deaths within the group, which is similar to other reports that only a small proportion of the total number of deaths, between 0%8
result from oesophageal cancer. However, oesophageal cancer mortality was significantly increased in the cohort when compared with the NI population. Since the first definition of BO in 1950,18
it has become apparent that the presence of SIM confers a greater risk of developing OAC.19,20
The findings of this study indicate that only patients with SIM have an increased mortality rate from oesophageal cancer, approximately eight times that of the normal population. Furthermore, males had more than twice the mortality rate from oesophageal cancer than females. These findings suggest that surveillance programmes could be limited to patients with SIM17,20
and targeted towards men. Although avoided mortality was not quantified and needs to be considered, the relatively low mortality from oesophageal cancer, even in these patients, calls into question the cost effectiveness of surveillance programmes that cannot be targeted at patients with a high risk of cancer.
Overall cancer mortality was not significantly raised in the cohort of Barrett’s patients. This is in keeping with the observation of Drewitz and colleagues21
who noted that 34% of the deaths among Barrett’s patients were from cancer, a rate similar to the percentage of deaths from cancer in males in the USA. Our study showed no significant increase in the mortality rate from colorectal cancer in comparison with the general population, indicating that previous suggestions of surveillance for colorectal cancer12,22
Increased mortality rates from diseases of the digestive system, especially peptic ulcer disease, were observed. Diagnosis of BO in such patients may have been an incidental finding during endoscopic procedures to investigate the conditions, which led to their deaths. Alternatively, increased acid secretion or decreased mucosal defence may be underlying pathophysiological mechanisms common to both BO and peptic ulcer disease.
Patients with BO (especially those with SIM) were found to have a significantly lower mortality rate from stroke than those in the NI population, suggesting a possible association between BO and stroke mortality. Further work is required to confirm or refute this association. Surveillance of patients with BO may have attributed to a reduction in deaths from stroke due to investigation for other medical conditions at their follow up appointments, or the “worried well” may be more likely to undergo endoscopy and have incidental BO diagnosed. However, in both of these circumstances we would expect a reduction in overall mortality, which was not observed in this study. Perhaps individuals with low vascular tone, and hence low blood pressure and stroke risk, also have disturbed oesophageal motor function, allowing gastro-oesophageal reflux and the development of BO.
This study reinforces the findings of previous studies that oesophageal cancer is an uncommon cause of death in patients with BO and that the increased mortality rate from oesophageal cancer is confined to patients with SIM. Additionally, the study shows that the overall mortality rate in Barrett’s patients is not increased when compared with that of the general population and indicates that these patients may have a reduced mortality rate from stroke.