Introduction: Inflammatory bowel disease (IBD), comprised of Ulcerative Colitis (UC) and Crohn’s Disease (CD), is caused by a combination of environmental factors, immune dysregulation, and genetic susceptibility. Other immune-mediated phenomena, like hypothyroidism, have also been observed in this population. Thus, we sought to explore clinical characteristics and outcomes among IBD patients with hypothyroidism compared to IBD patients without hypothyroidism.
Methods: In a retrospective chart review from a large, tertiary, academic medical center, baseline demographics and clinical data were extracted for patients diagnosed with either UC or CD and having at least one thyroid stimulating hormone (TSH) measurement from prior to 2016. Based on the presence of a documented hypothyroidism ICD-10 code, patients were then divided into two groups, those with IBD alone and those with both IBD and hypothyroidism, as described in Figure 1. Individual charts were then further examined for disease characteristics, biomarkers, healthcare utilization, medication use, and other comorbidities from 2016 to 2022. Demographic and clinical variables were then compared between the two groups, as seen in Table 1.
Results: We identified 166 adult IBD patients (CD 53%, UC 47%). The mean age was 62.9 years. Among these patients, 116 patients (69.9%) had IBD and hypothyroidism. The most common causes of hypothyroidism were Hashimoto, subclinical, and acquired hypothyroidism. No differences were noted in race, smoking status, or BMI. IBD disease location, behavior, and prevalence of extra-intestinal manifestations did not significantly differ between the two study groups. Both groups had similar number of colonoscopies, hospitalizations, as well as comparable medication use (SSRI/SNRI, steroids, 5-ASA, immunomodulators, biologics). However, patients with IBD and hypothyroidism had higher rates of anemia (p=0.03), hypoalbuminemia (p=0.007), and CRP elevations (p=0.002). Furthermore, patients with both IBD and hypothyroidism had a greater median number of emergency department visits (p=0.039) and axial radiography (p=0.002).
Discussion: IBD patients with hypothyroidism experience a more severe disease course with higher biomarkers of inflammation and healthcare utilization than those without hypothyroidism despite similar IBD phenotype and therapy exposures. This highlights a potential subgroup of IBD patients who may be at risk for increased disease severity and associated poor outcomes.
