Evolution of Surgery Risk in Crohn's Disease
While many individuals with Crohn’s disease require surgery for management, the risks of surgery are not well characterized in population-based studies. Advances in medical management may have influenced the risk of surgery over time. However, studies have not adequately evaluated the effect of smoking on temporal trends in surgery risk for Crohn’s disease. A mixed methodology approach was used to: 1) describe the morbidity and mortality associated with surgery in Crohn’s disease; 2) summarize the risk of first and second surgery in Crohn’s disease; 3) evaluate whether the risk of surgery has changed over time; and 4) assess whether smoking has influenced the risk of surgery in Crohn’s disease. In Alberta, postoperative morbidity (25%) and mortality (1.2%) was high for Crohn’s disease. A systematic review and meta-analysis found that the estimated pooled risk of surgery 10 years after the diagnosis of Crohn’s disease was 46.6% (95% Confidence Interval [CI] 37.7%-57.7%); however, the risk of first surgery in Crohn’s disease was significantly decreasing over time (meta-regression p- value<0.01). Another systematic review and meta-analysis identified that 10 years following the first surgery the estimated pooled risk of a second surgery was 35% (95% CI 31.8%-38.6%) and this risk was also decreasing over time (Cochran Q for subgroup comparison p-value<0.01). Finally, a nationally representative cohort showed that from 1996 to 2009 the risk of first surgery decreased significantly and the proportion of incident Crohn’s disease patients who have never smoked significantly increased annually by an estimated 3% (Risk Ratio [RR] 1.03; 95% CI 1.02-1.04). Furthermore, in older adults (>40 years at diagnosis) smoking was associated with twice the risk of surgery compared to those who did not smoke. The results of this dissertation demonstrate that surgery is associated with significant morbidity and mortality. Reassuringly, the risk of surgery is decreasing over time. In part, this decrease may be explained by fewer Crohn’s disease patients who are smokers at diagnosis. Thus, public health initiatives that reduce the prevalence of smoking in the general population may reduce the burden of Crohn’s disease.
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