Elevated BMI linked to more severe clinical course of Crohn’s disease

Overweight individuals with Crohn’s disease (CD) are older at diagnosis and have a shorter time to surgical intervention than those who are underweight, according to researchers. The correlation suggests that such patients may need more aggressive therapy earlier in the course of their disease. According to lead study author, there has not been substantial documentation that increased body mass index (BMI) is related to a more severe clinical course of CD. TNF-X production in adipose tissue is well documented, and this study is important because Crohn’s disease is an inflammatory-mediated disease. There are certain cytokines – notably TNF-X – that are thought to be primary mediators in the pathogenesis of the disease.

We postulated that patients with an elevated BMI and thus, theoretically, more adipose tissue could have a more severe clinical course of CD secondary to increased cytokine production. The researchers evaluated outpatient records of 148 patients with CD (88 female, 60 male) over a five-year period. Forty-eight patients (32.4 percent) had a BMI.25kg/m, and 100 (67.6 percent) had a BMI<25kg/m2. Patients with higher BMIs were significantly older at the time of diagnosis (media age, 35 years vs. 22.5 years, respectively; P=0.0001). The median duration of disease was 213 months for patients who had a BMI<25kg/m2, compared with 156 months for the subjects with elevated BMIs (P=0.05). The median time from symptom onset to disease diagnosis did not differ significantly between the groups, and neither did the number of surgeries or disease distribution. No difference in the escalation of medical therapy was noted between the groups. However, a statistically significant difference was found for median time to first surgery: 252 months for patients with a BMI<18.5 kg/m2, compared with 24 months for those with a BMI>25kg/m2 (P+0.04).

We demonstrated that patients deemed overweight have a much shorter time to their first surgical intervention compared to those deemed underweight. This suggests that patients who are heavier may contain more adipose tissue and therefore more TNF-X, resulting in a more severe clinical course. We also demonstrated that there was no difference in the time form symptom onset to actual disease diagnosis between these two groups. This is important, as it speaks against the presence of significant lead time bias. It’s not as though these people sustained disease for longer period of time and then were subsequently diagnosed later in their disease course. The findings could change the way physicians look at certain subgroups of patients with CD and may have clinical implications. Based on the study results, patients with a high BMI might benefit from earlier and more aggressive immunomodulation, which may delay the need for surgical intervention. It can be noted that the study is particularly relevant in the United States, as there is an escalating trend toward obesity.

The conclusion of the researchers is certainly one possibility. It also might imply that, for some reason, obese or overweight patients delay a visit to their physicians and do in fact get a diagnosis later in the course of Crohn’s disease. If this study’s findings are confirmed, it would show that there is yet another medical complication that is associated with obesity and another reason to lose weight.