LAUSR

Chronic inflammation is considered a pathological mechanism underlying multiple chronic disorders that are associated with substantial morbidity and premature mortality. We know that major cardiovascular events (e.g. myocardial infarction, stroke) are common within specific inflammatory disorders, including rheumatoid arthritis, psoriasis and inflammatory bowel disorders (e.g. Crohn’s disease, ulcerative colitis). In this issue of the European Journal of Preventive Cardiology, Sun and Tian report a metaanalysis on the major cardiovascular disease (CVD) events and related mortality outcomes from population-based studies on inflammatory bowel disorders. The study aggregated data from prospective cohort studies using fixed and random effects modelling to address heterogeneity bias within included studies. The authors observed that inflammatory bowel disorders were associated with cerebrovascular disorders, myocardial infarction and coronary heart disease. However, they concluded that there was no evidence that inflammatory bowel disorders were associated with an increased risk of CVD-related mortality. This study adds to the literature by synthesising data about CVD risk and CVD-related mortality outcomes among people diagnosed with inflammatory bowel disorders in population-based studies. Overall, the study findings support the view that inflammatory bowel disorders have a negative prognosis for CVD events. How can we then explain the lack of impact on CVD-related mortality? An important caveat of this study is the lack of inclusion of all-cause mortality as an outcome measure, a more reliable indicator of survival and quality of life. The use of all-cause mortality as an outcome would avoid the challenges around ascertainment bias and competing risk causes of death, acknowledged by the study authors. The latter is of notable importance given that cancer (e.g. colorectal cancer) and chronic obstructive pulmonary disease are among the primary causes of death among patients diagnosed with Crohn’s disease and ulcerative colitis. Another important caveat of the study is that it does not address a potential role of anti-inflammatory therapies in CVD-related mortality. Recent evidence, for instance, suggests that new biological anti-inflammatory therapies (e.g. canakinumab) may play a protective role against all-cause and cancer-related mortality. Whether a similar effect may be observed with regard to CVD-related mortality among patients with inflammatory bowel disorders remains unclear. It is also important to acknowledge that CVD mortality represents a long-term process, while inflammatory bowel disorders tend to have an early age at onset (i.e. commonly around 15–30 years of age). It may be thus that the meta-analysis of Sun and Tian mainly captured the short-term effects of inflammatory bowel disorders on CVD mortality. Studies stratifying patients with inflammatory bowel disorders on disease patterns (e.g. duration and activity of disorder, age at onset) could identify subgroups of patients with increased rates of CVD-related mortality. Before concluding that inflammatory bowel disorders are not associated with CVD-related mortality, we need to consider that inflammatory bowel disorders are reflective of a heterogeneous group of people in terms of their inflammatory burden and treatment choices. The evidence from the meta-analysis of Sun and Tian, reporting no greater risk of dying from CVDrelated mortality in patients with inflammatory bowel disorders, does not change the fact that these patients do present with an increased burden of CVD and poorer quality of life. What factors may determine the increased risk of major CVD events, given that inflammatory bowel disorders are associated with lower rates of traditional vascular risk factors? Recent evidence documented a direct link between several inflammatory biomarkers with arterial stiffness and