The risk for ischemic colitis (IC) is higher among older women with low diastolic blood pressure and those taking at least two antihypertensive medications, according to prospective data from more than 100,000 participants in the Women’s Health Initiative.
The study, published in the American Journal of Gastroenterology, also found that IC was twice as common among older women with a history of cardiovascular disease as among those without, and consuming more dietary fiber could have a protective effect, wrote lead author Sylvia Wassertheil-Smoller, PhD, of Albert Einstein College of Medicine, Bronx, New York, and colleagues.
“A systematic review published in 2004 noted that the reported incidence of IC in the general population varied from 4.5 to 44 cases per 100,000 person-years and concluded that the effect sizes of the most commonly reported risk factors were not adequately quantified,” the investigators wrote. “Since then, to our knowledge, there have only been two population-based studies of IC…and no prospective, longitudinal studies with extensive covariate data.”
To address this knowledge gap, Wassertheil-Smoller and colleagues analyzed prospective data from 100,825 women aged 65 years or older in the Women’s Health Initiative with an average follow-up of 13.1 years. The population was diverse across racial and ethnic groups, the investigators noted, and outcomes data were “extensive.”
The analysis relied upon Lasso Cox regression analysis to evaluate 40 variables associated with IC across a variety of domains, including known risk factors, biomarkers, psychosocial factors, dietary factors, medications, demographic factors, and comorbidities. Separate models were run on the full dataset and a subset of patients without a history of cardiovascular disease, including coronary heart disease, peripheral arterial disease, and/or stroke.
IC was twice as common among women with a history of cardiovascular disease (55.7 per 10,000 person-years; 95% CI, 50.0-61.4) as among those without (27.3 per 10,000 person-years; 95% CI, 26.4-28.2).
“We found a markedly higher incidence of IC in the Women’s Health Initiative than has been previously reported for a general population,” the investigators wrote. “This may partially be because women have been reported to have nearly twice the incidence of men and because our cohort was substantially older than in other earlier studies.”
Further analysis revealed a U-shaped risk curve between diastolic blood pressure and IC. The lowest risk was observed at 89 mm Hg, with an increased risk for 23% at 60 mm Hg (adjusted hazard ratio [aHR], 1.23; 95% CI, 1.09-1.39) and 46% at 50 mm Hg (aHR, 1.46; 95% CI, 1.20-1.77). Taking at least two antihypertensive medications compared with none was associated with a 62% increased risk (aHR, 1.62; 95% CI, 1.47-1.78). A slightly elevated diastolic blood pressure (100 mm Hg) was associated with a 3% increased risk, although this finding was not statistically significant.
“Previous findings in the Long Life Study of the Women’s Health Initiative indicated a similar U-shaped relationship of diastolic blood pressure to all-cause and cardiovascular mortality, except that the nadir in that relationship was 72 mm Hg,” the investigators wrote.
Dietary fiber could potentially counteract these risks, with a 6% risk reduction for each 10 g/d increase in fiber (aHR, 0.94; 95% CI, 0.89-0.97). Lower risk was also detected among Black women, who had a 27% lower risk than White women (aHR, 0.73; 95% CI, 0.63-0.83).
Finally, the study reported 10.6% all-cause mortality within 30 days after IC. Sepsis was identified as an important early mortality risk because 12.1% of deaths within 30 days of IC were due to sepsis compared with 4.3% of deaths over long-term follow-up.
A Balanced Approach
“The study is important because the study population is a large and well-established Women’s Health Initiative cohort,” Aasma Shaukat, MD, MPH, gastroenterologist and director of outcomes research for gastroenterology and hepatology at NYU Langone Health, New York City, told Medscape Medical News.
Shaukat suggested that the findings call for a balanced approach to IC prevention in older women.
“It is important to know that controlling high blood pressure, eating more fiber, and being physically active are important ways to reduce risk of IC,” she said. “At the same time, women should understand that a diastolic blood pressure of lower than 90 mm Hg is a risk factor for IC. If they are on medications for blood pressure, [they should] ensure it’s not dropping their diastolic BP below 90.”
Shaukat went on to suggest that more research is needed to understand the “risk of IC among those with controlled or uncontrolled high blood pressure, improvement in risk of IC with adoption of a high-fiber diet or exercise, and ways to reduce the risk of serious complications or death after IC.”
Study Co-author Michael Bohm disclosed having relationships with Amgen, Bayer, Medtronic, and others. Shaukat reported having no conflicts of interest.