At the intersection of two U.S. health epidemics - obesity and chronic pain - researchers from the University of Michigan Health System found black patients with chronic pain were less likely to have their weight or body mass index (BMI) recorded, even though they are at higher risk for having obesity when compared with their white counterparts.

This new study also revealed that obesity is related to greater disability and poorer functioning, over and above the impact of a person's pain level.

Obesity contributes to chronic pain and several other chronic conditions, leading to decreased health and quality of life. Chronic pain also leads to decreased health and quality of life, says senior author Carmen R. Green, M.D. Disparities in the chronic pain experience and obesity exist, with blacks more likely to be negatively impacted, she notes.

Black people also are more likely to experience disability and lower physical functioning than white people, when faced with chronic pain, says Green, associate professor of anesthesiology and health management and policy, and director of Pain Medicine Research at the U-M Medical School and School of Public Health. The study appears in the Journal of Pain.

"Assessing a patient's weight and height is necessary to calculate BMI. Once assessed, a dialogue can begin between the patient and health care team to address obesity," Green says. "These findings provide further evidence of the negative effect obesity, measured via BMI, can have on a person's overall health and well-being in general and on chronic pain in particular.

"This is a reminder about the importance of assessing height and weight and measuring BMI in patients with chronic pain, especially minorities."

However, the goal is made more difficult because black patients are less likely to have their BMI assessed, the study found. "Both chronic pain and obesity are reaching epidemic proportions. Considering their public health implications in terms of disability, BMI should be regularly assessed especially in populations who are at increased risk," Green says.

It is not clear why it was less likely black patients would have their BMI measured, even though they may be at increased risk for higher BMI and obesity, researchers say. But they point out that the gap could indicate a lower quality of care than what is provided to white patients.

BMI is a measure of body fat based on height and weight. According to the National Institutes of Health, people with a BMI lower than 18.5 are considered underweight; people between 18.5 and 24.9 are normal weight; people between 25 and 29.9 are overweight; and those with a BMI of 30 or higher are obese. This table shows the BMI of people at various weights and heights.

• Researchers studied 183 people - 92 white and 91 black, 68 men and 115 women, ages 31 to 46. New black patients attending a pain clinic at U-M were asked to participate, and were matched with a white chronic pain patient of the same gender and similar age.

• When the height and weight was available it was taken from the electronic medical record. Patients were asked to indicate on a diagram of the human body where they were in pain, how long they've been in pain and what caused it. They also were given the McGill Pain Questionnaire and the West Haven Yale Multidimensional Pain Inventory to evaluate the intensity of their pain and its impact on their life.

• The BMI was notably higher for blacks than whites (31.6 vs. 27.6). Blacks were less likely to have complete height and weight data in their records than whites (73 percent vs. 84 percent). Those without BMI data had higher pain severity scores.

In addition to Green, Julia Caldwell, M.D. and Tamera Hart-Johnson, M.S. were co-authors of the paper.

AETNA Quality Care Foundation provided funding for the study.

Reference: Journal of Pain, doi:10.1016, Body Mass Index and Quality of Life: Examining Blacks and Whites With Chronic Pain.