Physical activity reduced the risk of developing Crohns disease but not ulcerative colitis for participants in the Nurses Health Study and the Nurses Health Study II, according to a recent study.
Ulcerative colitis and Crohns disease affect nearly 1.4 million U.S. residents and lead to more than $6 billion in healthcare costs each year, according to past studies. Together, the conditions also are associated with loss of productivity and work disability. The researchers set out to explore whether there is an association between physical activity and the risk of ulcerative colitis and Crohns disease.
For the study, published Nov. 14 on the website of the British Medical Journal, the authors used data on 194,711 women enrolled in the Nurses Health Study and Nurses Health Study II. These women had provided information on physical activity and other risk factors every two to four years since 1984 and 1989, respectively, and followed up through 2010. They were asked about the average amount of time they spent each week doing activities including walking or hiking outdoors, jogging, running, bicycling, swimming laps, tennis, aerobics, racquet ball or squash, and other vigorous activities such as mowing the lawn.
Participants also reported their usual outdoor walking pace: unable to walk, easy (less than 2 miles per hour), average (2-2.9 mph), brisk (3-3.9 mph) or very brisk (4 mph or faster). Each activity was assigned a metabolic equivalent task, and a MET was assigned to walking based on pace. The researchers then calculated the MET hours per week.
The most active women, those in the highest fifth of physical activity, were less likely to be obese or smokers than those in the lower fifths. No significant differences in age, history of appendicectomy and use of NSAIDs, oral contraceptives or postmenopausal hormone therapy were observed among women in the different quintiles of physical activity.
During the 3,421,972 person-years of follow-up, 284 cases of Crohns disease and 363 cases of ulcerative colitis were documented. The researchers found an inverse association between risk of Crohns disease and physical activity. Active women with at least 27 MET hours per week of physical activity had a 44% reduction in the risk for developing Crohns disease compared with sedentary women (less than 3 MET hours a week). However, no association was seen between the risk of ulcerative colitis and physical activity.
When researchers took into account known risk factors such as age, smoking and BMI, the associations between physical activity and Crohns disease and ulcerative colitis were consistent.
Women in the highest fifth of physical activity had an absolute risk for ulcerative colitis and Crohns disease of 8 and 6 events per 100,000 person-years, respectively. Those in the lowest fifth of physical activity had absolute risks of 11 and 16 events per 100,000 person-years, respectively.
Full study: www.bmj.com/content/347/bmj.f6633?etoc=#aff-1