Obesity Is Associated with Increased Risk of Pain in Elderly Patients

February 22, 2011

Elderly patients with abdominal obesity face a twofold increase in prevalence of chronic pain, independent of other components of metabolic syndrome.

Study shows that abdominal obesity is associated with a nearly twofold increase in the probability of chronic pain among elderly individuals.

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, and examined components of the metabolic syndrome, insulin resistance, high-sensitivity C-reactive protein (hsCRP), and the presence of painful comorbidities. They also looked at comorbid depression and anxiety and the use of NSAIDs “to investigate their potential role as confounders of the pain—obesity relationship.”

EAS participants undergo annual assessments that include “neurologic and cognitive testing, anthropometric measures, blood pressure, and collection of fasting blood samples.” Subjects were also assessed for insulin, hsCRP, triglycerides, HDL, and depression symptoms. Investigators measured BMI, assessed for metabolic syndrome (according to National Cholesterol Education Panel’s Adult Treatment Panel III), and assessed for experience of pain (in the prior three months to the clinic visit) using the Total Pain Index (TPI). 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 of metabolic syndrome consistently associated with pain. Higher hsCRP was also associated with higher TPI scores. The authors looked at several adjusted models that analyzed individual components of metabolic syndrome to “further examine the role of abdominal obesity as the potential driver of the relationship between metabolic syndrome and 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.” Other factors (hsCRP, osteoarthritis, etc) were associated with pain, but only abdominal obesity was linked to the presence of chronic pain and higher pain scores, with individuals with abdominal obesity estimated to have a 70% increased likelihood of having pain. The authors wrote that the finding that “central adiposity was independent even of painful comorbidities suggests that an alternative pathway accounts for the pain—obesity association, which may be bidirectional.” They suggested that 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 one seemingly obvious solution — weight loss – 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).

Related Studies

A previous study on this topic also produced similar findings. The authors of a study published in the January 2009 issue of the Journal of the American Geriatrics Society that looked at data from the Einstein Aging Study from more than 800 men and women, age 70 and older, found that “obese individuals were twice as likely to have chronic pain and severely obese individuals were more than four times as likely to have chronic pain, even after adjusting for other risk factors. Individuals in higher BMI categories also had more frequent and more severe pain, along with a higher number of painful bodily locations than those in lower BMI categories.”