Studies have shown that pain prevalence and severity is linked to obesity and that pain has a greater impact on functionality and quality of life in obese individuals. Analysis of data from the Einstein Aging Study (EAS) has shown that self-reported BMI “was associated with an increased prevalence of chronic pain” among the elderly participants in that study. However, according to the authors of “Mechanisms of Association between Obesity and Chronic Pain in the Elderly,” published in the January 2011 issue of Pain, the “mechanisms underlying the relationship between pain and obesity remain unclear, particularly in older adults.” To investigate and clarify these mechanisms, the authors looked at data from more than 400 EAS participants, age 70 and older. More than three-quarters of subjects (76%) reported pain of any severity during the prior three months at one or more locations, with slightly more than half of subjects (52.3%) meeting the criteria for chronic pain. The authors reported that chronic pain was significantly associated with depression score among participants, and that both BMI and abdominal obesity were associated with chronic pain, with the likelihood that a subject experienced chronic pain increasing with each unit of BMI. Individuals with abdominal obesity “were twice as likely to report chronic pain.” Roughly one-third of subjects (34%) met the criteria for metabolic syndrome, with prevalence showing “a trend toward greater frequency among those with chronic pain.” Abdominal obesity was the only individual component ofmetabolic syndrome consistently associated with pain.
After adjusting for demographic characteristics and other factors, abdominal obesity was the only component that independently significantly predicted pain; subjects with abdominal obesity had an 83% increased likelihood of having chronic pain. Other models that adjusted for fasting insulin level, fasting glucose, a history of diabetes, hsCRP, osteoarthritis, and neuropathy “did not attenuate the relationship between abdominal obesity and pain.” In their discussion, the authors wrote that these results “contribute to the growing body of evidence that pain among community dwelling, well elderly individuals is associated with obesity.” Although they performed several multivariable analyses to look for “potential mechanistic links between the co-occurrence of obesity and pain… none of these potential mediators fully accounted for the relationship.” The authors suggested pain “may lead to decreased physical activity, depression, and obesity,” and may also lead to “cortisol secretion that contributes to truncal obesity.” Conversely, “the metabolic derangements of obesity may predispose to pain.” Although these results point to a strong relationship between obesity and pain in the elderly, the benefits of losing weight have yet to be demonstrated. The authors recommend that clinicians advising elderly patients to restrict caloric intake “must take into consideration the potential risk of weight loss in this population,” including the effects of losing lean body mass and bone mineral density (although there are published consensus statements that support weight loss interventions that minimize the loss of lean body mass in obese elderly).