Patients with, or at high risk for, knee osteoarthritis who consume higher amounts of dietary total or cereal grain fiber were less likely to experience moderate and severe knee pain compared with patients whose dietary intake of fiber was lower, according to the results of a recent study by Zhaoli Dai, PhD, MS, Postdoctoral Fellow, Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, MA, and colleagues.
As one of the primary causes of disability in patients with osteoarthritis, chronic pain is traditionally managed with nonsteroidal anti-inflammatory drugs (NSAIDS). Because of the side effects associated with the use of these agents, safer alternatives, including dietary approaches, are a suggested option for preventing or managing pain in patients with knee osteoarthritis. Although the association between dietary fiber and lower risks for mortality, cardiovascular disease, type 2 diabetes, and depression has routinely been reported in the literature, Dr Dai and colleagues asserted that there have been no studies to date examining the relationship between dietary fiber intake and knee pain in older adults.
The investigators conducted their study over a time frame of 8 years, during which they examined this association in patients who have, or are at high risk for, knee osteoarthritis. They used data from the multicenter Osteoarthritis Initiative cohort, which comprised 4796 men and women aged 45 to 79 years who were recruited between 2004 and 2006. Patients were excluded from the study if they were found to have had a total or partial knee replacement at baseline, were missing dietary information, or had extreme caloric intake.
During the baseline assessment and at annual follow-ups thereafter (up to 96 months), Dr Dai and colleagues assessed knee symptoms using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale of 5 activity items, including walking, stair climbing, nocturnal, rest, and weight bearing. These activity items, which were scored individually on a scale from 0 (no difficulty) to 4 (extreme difficulty), contributed to a total WOMAC pain score that ranged from 0 points (no pain) to 20 points (worst pain).
Among 4470 eligible patients (ie, those who were not excluded or lost to follow-up), the investigators identified 4 unique WOMAC knee pain trajectory patterns—“no pain” (34.5%), “mild pain” (38.1%), “moderate pain” (21.2%), and “severe pain” (6.2%)—between months 12 and 96.
“In the present study, we identified four distinct WOMAC knee pain trajectory patterns over an 8-year course and found that dietary total or cereal grain fiber intake was inversely associated with likelihood of belonging to the moderate and severe pain groups. At the highest quartile intake of total fiber, significantly lower odds were found for the membership in moderate and severe pain patterns as compared with the lowest quartile using ‘no pain’ as the reference group,” Dr Dai and colleagues reported.
Patients who had higher dietary fiber intakes tended to be more physically active, older in age, and have higher education levels than those who consumed less fiber. Patients with higher dietary fiber intake were also less likely to use NSAIDs, suffer from depression, or smoke tobacco than their counterparts.
“Our findings suggest that high dietary total or grain fiber, particularly in the recommended daily fiber average intake of 25 grams per day, was associated with lower risks of belonging to moderate to severe pain development patterns over 8 years,” the investigators concluded.