Ulcerative colitis is now seen as an independent risk factor for hypertension, while new research shows other forms of inflammatory bowel disease (IBD) are not independent risk factors.

A team, led by Jinshen He, Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, identified the association between IBD and the incidence of hypertension.

IBD and Hypertension

IBD is often accompanied by systemic inflammation, which can be closely related to hypertension. However, there is not much research on the association between IBD and hypertension.

“Studies have pointed out that systemic inflammation is involved in atherosclerosis, and that systemic inflammation increases the risk of acute arterial events, which can be alleviated by anti-inflammatory treatment,” the authors wrote. “IBD has been considered a potential risk factor for acute arterial events in addition to traditional cardiovascular risk factors. However, these studies have mainly focused on hard endpoints such as cardiovascular and cerebrovascular events, and few studies focused on the relationship between IBD and hypertension.”

In the study, the investigators used data from the UK Biobank for identify statistics on IBD onset and the incidence of hypertension.

This association was analyzed using a multivariate Cox regression analysis. The team also performed propensity score matching for sensitivity analysis.

A Large Cohort

The study included 281,064 participants, 0.8% (n = 2376) of which were diagnosed with IBD at baseline. Of the entire cohort, 7.2% (n = 20,129) of participants developed hypertensions with a median follow-up of 8.1 years. The patient population age ranged from 37-69 years during the time of recruitment between 2006-2010. The mean age was 55 ± 8 years old.

Each participant received a 90 minute session that included questionnaires, physical examinations, blood sample collections, and interviews at the recruitment. The patients were then matched with the NHS Central Register database.

Participants with a diagnosis of hypertension at recruitment, a history of cardiovascular diseases, diabetes, or stroke at recruitment, a new diagnosis of IBD during follow up, or those with a lack of baseline or follow-up data were excluded.

The investigators sought a primary outcome of the occurrence of hypertension determined by the primary care, hospital admission, or death register during follow-up.

The Prevalence

The results show a higher cumulative risk of hypertension in patients with IBD compared to the general population (10.9% in ulcerative colitis, 7.7% in Crohn's disease, and 9.3% in IBD unclassified vs. 7.1% in non-IBD, P <0.001).

The multivariate Cox regression showed ulcerative colitis was independently associated with subsequent occurrence of hypertension (HR, 1.30; 95% CI, 1.11-1.52; P = 0.001), while Crohn’s disease or IBD unclassified were not. They also found both steroid use (HR, 1.33; 95% CI, 1.20-1.47; P <0.001) and immunosuppressive agents (HR, 1.32; 95% CI, 1.16-1.50; P <0.001) were risk factors for hypertension.

The investigators also did certain subgroup analysis and interaction tests in the ulcerative colitis group.

The risk of ulcerative colitis for hypertension differed between different sub-populations with (HR, 1.01; 95% CI, 0.75–1.36; P = 0.933) and without anxiety (HR, 1.46; 95% CI, 1.21–1.76; P <0.001), while there was a significant interaction effect found between ulcerative colitis and anxiety (P = 0.040).

Ulcerative colitis was also a risk predictor for hypertension only for the use of anti-hypertension drugs only in individuals without the drug history (HR, 1.36; 95% CI, 1.15-1.59; P <0.001). The interaction between ulcerative colitis and the use of anti-hypertension drugs was relatively borderline (P = 0.078).

Ulcerative colitis was also the risk only in the subpopulation without a history of immunosuppressive agents (HR, 1.35; 95% CI, 1.14-1.59; P <0.001). Ulcerative colitis was a risk factor for hypertension in both individuals with (HR, 1.77; 95% CI, 1.07-2.93; P = 0.027) and those without (HR, 1.27; 95% CI, 1.07-1.50; P = 0.006) steroid use.

The propensity matching analysis showed ulcerative colitis had a robustness as a risk factor for the prediction of hypertension (HR, 1.56; 95% CI, 1.21-2.03; P = 0.001).

“In IBD patients, [ulcerative colitis] rather than [Crohn’s disease] is associated with a higher risk for the incidence of hypertension compared with general population,” the authors wrote. “Close monitoring of hypertension might be required in clinical practice.”

The study, “Ulcerative colitis increases risk of hypertension in a UK biobank cohort study,” was published online in the United European Gastroenterology Journal.