NEW YORK (Reuters Health) – Half of people aged 70 and older suffer from some type of chronic pain, and women and the obese are particularly vulnerable, new research shows.

Chronic pain, defined as pain that persists for three months or longer, is known to be common among older people, Dr. Richard B. Lipton and colleagues from the Albert Einstein College of Medicine in the Bronx, New York, note. Obesity is becoming increasingly prevalent among US seniors, they add, so studying the relationship between excess weight and chronic pain among older people — as well as the role of conditions that might influence both pain and obesity, such as mental health problems, should be studied.

To that end, Lipton and his team looked at 840 men and women participating in the Einstein Aging Study, an ongoing investigation of people 70 and older living in the Bronx.

Overall, 52 percent had some type of chronic pain, including 40 percent of men and 59 percent of women. People with chronic pain were at double the risk of having symptoms of depression or anxiety compared to those who were pain-free. Chronic pain was twice as common among obese people as normal-weight individuals, and four times more common among the severely obese.

Obese people were more likely to have pain in virtually every part of the body than were normal-weight people, including the head, neck, or shoulder; back, legs or feet; or abdomen or pelvis.

Even after the researchers accounted for depression, anxiety, high blood pressure, and diabetes, as well as age, gender and education, the relationship between obesity and chronic pain remained strong.

Obesity could contribute to chronic pain by adding stress to the joints, Lipton and his colleagues say. In addition, obesity promotes inflammation, which could be a contributing factor.

More research is needed, they conclude, to understand whether obesity plays a causal role in chronic pain, and if so what mechanisms might be involved.

SOURCE: Journal of the American Geriatrics Society, January 2009.