By Michael Smith, North American Correspondent, MedPage Today Published: March 21, 2011 Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

More than one in 10 people in a prospective cohort developed chronic widespread pain over a four-year period and most of them were involved in a traumatic event during that time, researchers reported.

Among those who reported new, widespread chronic pain, 43% said they had experienced a traffic accident, surgery, or broken bones over the same period, according to Gareth Jones, PhD, of the University of Aberdeen in Aberdeen, Scotland, and colleagues.

In contrast, only 36% of those who remained pain-free reported such an incident, Jones and colleagues reported online in Arthritis Care & Research.

Note that among those who reported new, widespread chronic pain, 76% said they had experienced a traffic accident, surgery, or broken bones over the same period.

Explain that traffic accidents alone was a significant predictor of new chronic widespread pain but lost significance after further adjustment for anxiety and sleep problems.

Much of the difference – which approached but did not reach statistical significance — was driven by traffic accidents, workplace injuries and fractures, Jones and colleagues reported.

Chronic widespread pain, according to the American College of Rheumatology, is pain above and below the waist, or on both the left and right sides of the body, for three months or longer.

Earlier research has suggested the prevalence of the condition a primary characteristic of fibromyalgia — is about 11% to 13%. People with chronic widespread pain often attribute it to a single precipitating condition, such as a car accident, but there is little evidence to support that, Jones and colleagues noted.

To help fill the gap, they turned to the EpiFunD Study (for Epidemiology of Functional Disorders), a large prospective cohort study in northwest England.

At the start of the study, 6,290 people were recruited from three general practices in Manchester, England and were asked to fill out a questionnaire, part of which asked about chronic pain.

For this study, the researchers asked the same questions four years later of those who had been chronic pain-free at baseline. All told, 4,444 were known to be available for follow-up and 2,069 completed a second questionnaire, Jones and colleagues reported.

Of those, 241 — or 11.6% — said they now had chronic widespread pain and 37.2% reported at least one traumatic event over the same period, including traffic accident, workplace injury, surgery, fracture, inpatient treatment for any other reason, and, in women, childbirth.

More people with chronic widespread pain reported a traumatic event — 88 of 203 versus 596 of 1,638 — and the crude odds ratio was 1.34 with a 95% confidence interval from 0.996 to 1.80. While that approached significance, the researchers noted, adjustment for age, sex, baseline pain status, and the general practice from which participants were recruited attenuated the odds ratio even further.

In an analysis adjusted for age, sex, general practice and baseline pain status, traffic accidents alone remained a significant predictor of new chronic widespread pain.

The odds ratio was 1.84, with a 95% confidence interval from 1.10 to 3.11, Jones and colleagues reported, but it lost significance after further adjustment for anxiety and sleep problems.

Nonetheless, they argued, there is “some evidence to suggest that involvement in a road traffic accident, specifically, may confer an increase in the risk” of the condition.

Future research should try to determine what specific aspects of traffic accidents might be responsible, they concluded.

The researchers cautioned that the loss of more than half of the cohort to follow-up reduced the study’s statistical power. And, they added that it was not possible to tell which came first chronic pain or a traumatic event.