Background: There is growing interest in how psychological disturbances can impact on disease activity in IBD through neuro-humoral mechanisms, but research in this field is limited and conflicting. The impact of co-existing depression at the time of IBD diagnosis and its impact on subsequent disease activity through IBD medication usage and surgery has not previously been studied. We aimed to investigate whether baseline depression in patients diagnosed with Crohn's disease (CD) affects the requirement for steroids, thiopurines and intestinal surgery using a nationally representative UK research database.
Methods: We used the Clinical Practice Research Datalink to identify incident cases of patients with CD between 1998–2014. Demographic data including age at diagnosis, sex, body mass index, social and smoking status were extracted as well as prescription data for IBD medications including 5-aminosalicylic acids (5ASA), corticosteroids (CS) and thiopurines (TP). Additionally, prescribing data for the most commonly used anti-depressant medications (ADM) were obtained. A patient was considered to have baseline depression if they had either a prescription for ADM or a Read code for depression within the period 6 months prior to and up to 3 months after the formal IBD diagnosis using an established methodology . We compared the proportion of patients receiving 5ASA, CS and TP at 6 and 12 months from IBD diagnosis between patients with and without a diagnosis of depression at diagnosis. We generated a Cox regression model to estimate the risk of CS use, TP use and requirement for surgery in patients with baseline depression.
Results: We identified 6237 patients with CD in the study period. Depression at IBD diagnosis was present in 13%. Amongst CD patients with depression at diagnosis there was a higher proportion of females (72% vs 51%, p<0.001), a higher proportion of smokers (39% vs 29%, p<0.001) and a higher proportion of IBS co-diagnosis (25% vs 16%, p<0.001) compared to those without depression. There were no significant differences in medication usage at 6 months between patients with and without baseline depression (5ASA: 45% vs 47%, CS: 19% vs 20%, TP: 17% vs 16%). Similarly, there were no differences in medication usage at 12 months between patients with and without baseline depression (5ASA: 48% vs 50%, CS: 24% vs 25%, TP: 21% vs 22%). In the multivariate regression analysis, depression at baseline was not significantly associated with CS use (HR 0.93, 95% CI 0.72–1.19, p=0.55), TP use (HR 1.13 95% CI 0.94–1.35, p=0.20) or intestinal surgery (HR 0.72 95% CI 0.48–1.10, p=0.13).
Conclusions: In patients with CD, depression at IBD diagnosis does not appear to impact on medication usage or the need for surgery in the first year after diagnosis.
 Michael Moore, (2009), Explaining the rise in antidepressant prescribing: a descriptive study using the clinical practice research datalink, BMJ