Association Between Affective-Cognitive Symptoms of Depression and Exacerbation of Crohn's Disease.

OBJECTIVES: The prevalence of depression is high in patients with Crohn's disease (CD). We examined the influence of affective-cognitive symptoms of depression on the risk of exacerbation of CD. METHODS: We studied 2,144 adult volunteers with a self-reported diagnosis of CD who completed a baseline survey that included demographics, CD status, and an affective-cognitive index of depression. Linear and logistic regression analyses were used to determine whether CD status at 12 months was associated with the baseline measure of depression. Analyses were adjusted for confounders including age, gender, race, baseline disease activity, disease duration, prior hospitalization and surgery, corticosteroid and anti-TNF use, medication adherence, body mass index, current smoking, education, and sleep quality. RESULTS: Depression was significantly associated with subsequent increases in SCDAI score in both unadjusted (P<0.001) and adjusted (P<0.001) analyses. This association was non-linear, with a shallower slope for lower levels of depression. A 10-point increase in depression t-scores from 55 to 65 was associated with a 18.6-point increase in SCDAI (95% CI 11.5-25.6) and an odds ratio of 1.27 for SCDAI>150 at follow-up (CI: 1.01-1.60). We also found a significant association between depressive symptoms and hospitalization. CONCLUSIONS: Cognitive-affective depressive symptoms were significantly associated with a risk of exacerbation of CD and hospitalization.

The Comorbidity of Patient-Reported Crohn's Disease Activity and Depression: The Role of Health Behavior Mediators.

Background: Longitudinal research reveals a unidirectional relationship between a nonsomatic symptom of depression, a negative view of the self, and later reported Crohn's disease (CD) activity. We evaluated whether health behaviors mediated this association using a longitudinal design. Methods: We studied 3304 adult volunteers with a self-reported diagnosis of CD who completed a baseline survey that included demographics, CD activity, a symptom-specific index of depression, and measures of physical activity, smoking, and sleep quality. Crohn's disease status and the cognitive index of depression were also measured 6 and 12 months after the baseline evaluation. We specified single-mediator and multiple-mediator models to elucidate the depression-disease activity relationship. Results: Among 2395 females and 909 males, we found a significant mediation effect for activity level (P < .001) after adjusting for age, sex, and body mass index. There was no evidence that sleep quality and smoking are significant single mediators. When we considered multiple mediation models, smoking and less activity partially mediate the depression-CD association. Conclusions: Smoking and lower levels of physical activity are potential mediators of the unidirectional association between a nonsomatic symptom of depression-a negative view of the self-and patient-reported CD activity. Evaluating and treating specific symptoms of depression may reduce the frequency of CD exacerbations.

Does Reverse Causality Underlie the Temporal Relationship Between Depression and Crohn's Disease?

BACKGROUND: Studies suggest that there is a temporal relationship between depression and Crohn's disease (CD) activity. However, these studies assumed a unidirectional relationship and did not examine the possibility of reverse causality and the risk of a spurious association due to the overlap of symptoms underlying the depression-CD relationship. We evaluated the existence of reverse causality reflected in a possible bidirectional relationship between patient-reported CD activity and an affective-cognitive dimension of depression. METHODS: We studied 3307 adult volunteers with a self-reported diagnosis of CD who completed a baseline survey that included demographics, CD activity, and an affective-cognitive index of depression. Crohn's disease status and the affective-cognitive index of depression were also measured 6 and 12 months after the baseline evaluation. We used structural equation models to evaluate whether the effect of depression on future CD activity is stronger than the effect of CD activity on future depression. We calculated the likelihood that each of these hypotheses is supported by the data and calculated the likelihood ratio to provide a relative measure of which hypothesis best accounts for the data. RESULTS: The results of the informative hypothesis testing showed the most support for the hypothesis stating that an affective-cognitive dimension of depression is a stronger predictor of patient-reported CD activity than the converse. CONCLUSIONS: The hypothesis that an affective-cognitive dimension of depression predicts patient-reported exacerbation of CD is 218 times more likely to account for the data than the converse.