Although depression in the absence of gastrointestinal (GI) symptoms is not associated with subsequent inflammatory bowel disease (IBD) development, when GI symptoms are present, the patient should be evaluated for IBD. These findings, published in Gut, are based on new study insight that groups with CD and UC “have a higher prevalence of depression than matched control groups in the years prior to IBD diagnosis,” according to the investigators.
The nested case-control study included data from the Clinical Practice Research Datalink, which contains longitudinal electronic health records from 18 million patients. Using the database, the investigators identified 5874 patients with incident Crohn disease (CD) and 13,681 patients with incident ulcerative colitis (UC) diagnosed between 1998 and 2016. Each patient with CD or UC was matched to 4 control individuals without CD (n=23,496) or UC (n=54,724) based on age and sex. The investigators measured patient exposure to prevalent depression 4.5 to 5.5 years before IBD diagnosis.
In the 10 years that preceded IBD diagnoses, the prevalence of depression in patients who developed either CD or UC was similar to that of control patients (CD, 1.7% vs 1.6%; UC, 1.7% vs 1.5%,). “However, as early as 9 years before diagnosis, UC cases had a higher prevalence of depression compared with the control group, increasing to 5.9% of UC cases vs 4.7% of controls in the year before diagnosis,” the investigators said. This translated to a risk difference of 1.2% (95% CI, 0.7%-1.7%).
A similar pattern was observed in patients with CD 7 years prior to IBD diagnosis. The study authors found that 6.1% of CD cases had prevalent depression vs 4.5% of control cases the year before diagnosis (risk difference, 1.6%; 95% CI, 0.8%-2.3%).There were 4531 patients with CD and 10,829 patients with UC with follow-up data that covered the 5-year pre-IBD diagnosis exposure period. Notably, these CD and UC cases were “more likely to have prevalent depression during the exposure period than their respective control groups,” the researchers said.
After adjusting for socioeconomic and smoking status, the investigators found that individuals with depression had an increased risk of developing CD (odds ratio [OR], 1.05; 95% CI, 0.78-1.42) or UC (1.21; 95% CI, 0.99-1.47) compared with those without depression. Individuals with depression and prior GI symptoms were at higher risk for developing CD (OR, 1.21; 95% CI, 0.82-1.77) or UC (OR, 1.52; 95% CI, 1.19-1.94). A model using “a broader definition of prevalent depression to account for under reporting in primary care” found that only those with depression and prior GI symptoms were at an increased risk for CD (OR, 1.41; 95% CI, 1.04-1.92) or UC (OR, 1.47; 95% CI, 1.21-1.79).
This study may have been limited by inaccuracies in coding and completeness, which could have affected the identification of depression. The study authors noted that some previous studies have suggested that up to 50% of depression is not detected by primary care; therefore, the prevalence of depression could have been underrepresented in this study.
The investigators concluded that individuals with CD and UC “have a higher prevalence of depression than matched control groups in the years prior to IBD diagnosis.”
Blackwell J, Saxena S, Petersen I, et al. Depression in individuals who subsequently develop inflammatory bowel disease: a population-based nested case-control study. Gut. Published online October 27, 2020. doi:10.1136/gutjnl-2020-322308.