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Letter: previous exposure to corticosteroids increases the risk of post‐discharge venous thromboembolic events in patients with inflammatory bowel disease—author's reply

EDITORS, I thank Drs. Zeng and Gan for their interest in our study and thought‐ ful comments.1,2 They performed a meta‐analysis to investigate the impact of corticosteroids on the risk of venous thromboembolism (VTE) after hospital discharge and concluded “Previous exposure to corticosteroids significantly increases the risk of post‐discharge VTE in surgical or non‐surgical IBD patients.” This conclusion was based on three additional retrospective, observational studies from unique administrative data sets.3‐5 Traditionally, corticosteroids have been associated with VTE risk in IBD.6‐8 However, these studies were predominantly based on hospitalised and post‐surgical populations and did not examine post‐discharge patients separately. The existing literature has also not been able to separate the impact of IBD therapy from disease activity or additional confounders to establish a causal relationship between corticosteroids and VTE. This becomes particularly rele‐ vant for the studies included in Zeng and Gan's meta‐analysis, which did not directly assess IBD activity. Furthermore, two of the three studies consisted exclusively of surgical cohorts and only controlled for a limited number of confounders, which did not include emergent surgery, an established risk factor for VTE.9 Therefore, it remains unknown if corticosteroid exposure truly “increases the risk” or is simply a surrogate marker for severe disease and/or requirement for emergent surgery. Although corticosteroids were not significantly associated with VTE risk in our study, the effect size and direction of the effect were similar to the studies included in Zeng and Gan's meta‐analysis.2 The lack of statistical significance in our study may simply be a type II error related to our single centre study with relatively few events. It is also possible that the association between corticosteroids and VTE risk is not as strong after hospital discharge as it is during hos‐ pitalisation or in the early stages of a flare. This would be likely if corticosteroids were simply a surrogate marker of disease severity and overall poor health status, whereby the association between corticosteroids and VTE risk would diminish after hospital discharge when patients become more mobile, nutritionally replete and have a reduced burden of inflammation. Given these limitations, adequately powered studies that are able to control for disease activity and additional confounders are needed to determine if corticosteroids are independently asso‐ ciated with VTE risk following discharge. This is also important to determine if corticosteroid exposure should be included as a vari‐ able in clinical predictive tools to guide shared decision making for extended thromboprophylaxis.