Meta-analysis: Mortality in Crohn's Disease

C. Canavan; K. R. Abrams; J. F. Mayberry


Aliment Pharmacol Ther. 2007;25(8):861-870. 

In This Article

Summary and Introduction

Aim: To perform a meta-analysis is of published literature reporting standardized mortality ratios (SMR) for Crohn's patients from 1970 to date.
Methods: Medline search identified relevant papers. Exploding references identified additional papers. When two papers reviewed mortality of one patient group at different times, the later publication was used.
Results: Of 13 papers identified, three studies reported SMR below 1.0, two others had confidence intervals including 1.0. All other studies reported mortality higher than the general population. Meta-analysis using a random effects model shows the pooled estimate for SMR in Crohn's disease is 1.52 (95% CI: 1.32 to 1.74 [P < 0.0001]). Meta-regression shows the SMR for these patients has decreased slightly over the past 30 years, but this decrease is not statistically significant (P = 0.08).
Conclusion: Assessing evidence from original studies and conducting a meta-analysis shows age-adjusted mortality risk from Crohn's disease is over 50% greater than the general population. Whilst mortality has improved since the condition was first recognized, further evaluation of the patients studied in the cohorts included here is necessary to assess more recent changes in clinical practice.

Incidence of Crohn's disease has been reported as becoming stable in the USA over the past 20 years,[1] but prevalence is still higher than in previous decades.[1,2,3] In Europe, however, the incidence and prevalence are still increasing.[4,5,6] A recent study in the UK used data from primary care to report a prevalence of 144.8 cases per 100 000.[7] The prevalence of Crohn's disease in North America is currently estimated as ranging from 26.0 to 198.5 cases per 100 000 persons, which equates to 400 000-600 000 patients with Crohn's disease in North America alone.[8]

The first study into mortality in Crohn's disease was published in 1970.[9] Since then there have been numerous reports of standardized mortality ratios (SMR) for Crohn's disease that vary from 0.72[10] to 2.67.[11] Standardized mortality ratios are calculated as the ratio of deaths observed in a cohort to those expected in a group of the same size from the general population in the same area and standardized for age and sex of the individuals in the study cohort. Mortality data are important because they allow patients to be aware of prognosis and make informed decisions about treatment. They also provide clinicians with an indicator of the success of their management and if this has improved over time. Current literature reporting mortality vary so much in their results[10,11] that an accurate analysis of the SMR from this data is of importance. It will help establish whether Crohn's disease is a benign condition or if it carries a risk of increased mortality. Accurate data are also of importance to insurers when calculating risks for life policies.[12,13,14] This systematic review and meta-analysis of published data aims to provide an accurate overview of the current risk of mortality in Crohn's disease and how this risk has changed over time.


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