Daniel M. Keller, PhD

June 03, 2013

PHILADELPHIA, Pennsylvania — Patients with chronic obstructive pulmonary disease (COPD) are at high risk for persistent pain, report researchers, who say the risk is second only to that of patients with osteoarthritis or rheumatoid arthritis.

"Once you adjusted for all other factors to include depression, anxiety, and psychoses, COPD was still very predictive of chronic pain, and in particular, chronic use of opioids, both short acting and long acting," Melissa Roberts, MS, senior research associate at the Lovelace Clinic Foundation and a doctoral candidate at the University of New Mexico College of Pharmacy in Albuquerque, told Medscape Medical News.

Patients with COPD often have multiple sources of pain, including neuropathic, muscle, inflammatory, and mechanical or compressive.

In a retrospective analysis presented here at the American Thoracic Society (ATS) 2013 International Conference, researchers compared 15,904 patients with COPD to 7952 with other chronic diseases for evidence of chronic pain and for healthcare utilization over a period of 1 year.

Investigators identified patients over age 40 years from a managed care population in the southwestern United States. They determined diagnoses, pain treatments by procedure codes, and outpatient prescription claims.

They defined chronic pain as similar pain persisting 6 weeks from an initial event.

"We found that overall, pain is pretty common among all these people with chronic disease, but it's much more prevalent among COPD patients to an extent that could not be explained by their other comorbidities," Roberts reported.

 
We found that overall, pain is pretty common among all these people with chronic disease, but it's much more prevalent among COPD patients. Melissa Roberts
 

More patients with COPD, 59.8%, had chronic pain than patients with other chronic disease (51.7%; P < .05). The patients with COPD also had evidence of greater use of pain medications (41.2% vs 31.5%; P < .001).

The chronic conditions affecting patients without COPD were Alzheimer's disease, atrial fibrillation, cancers, chronic kidney disease, diabetes, heart failure, ischemic heart disease, stroke, transient ischemic attack, and osteoarthritis or rheumatoid arthritis. For these conditions except arthritis, the prevalence of pain was less than in the COPD cohort (P < .01 for all).

The prevalence of chronic pain was 70.2% with arthritis vs 59.8% among the patients with COPD (P < .001). And more of the patients with arthritis used pain medications compared with those who had COPD (44.8% vs 41.2%; P < .001).

Patients with COPD used a variety of classes of pain medications. "They use a lot of everything," Roberts said. "They use quite a bit of antidepressants and anxiolytics. Their use of short-acting opioids was pretty high."

Among patients with chronic use of pain medications, more with COPD, 24.2%, used short-acting opioids compared with other patients, 15.1%; in addition, more patients with COPD used long-acting opioids (4.4% vs 1.9%; both P < .001).

Patients with COPD who have chronic pain were more likely to be female, have more comorbid conditions, and have more inflammatory pain than other patients with chronic pain (P < .001). Interestingly, chronic pain did not correlate with the degree of lung function impairment in the patients with COPD.

Important Comorbidity

Coauthor Douglas Mapel, MD, medical director of the Lovelace Clinic Foundation, pointed out that the investigators wanted to exclude the influence of pain on any increased prevalence of comorbid conditions among the patients with COPD. "Even after adjusting for the increased comorbidities or taking osteoarthritis completely out of the equation, setting every patient with osteoarthritis aside, you still see this increased prevalence of pain. So there is something — an independent association — between COPD and chronic pain that's not explained," he said.

He added that in a chart review in a different study, about 84% of the patients with COPD had a history of smoking.

Asked by Medscape Medical News to comment on the study, David Mannino, MD, from the University of Kentucky in Lexington, said that his gut impression is that chronic pain in patients with COPD is related to their smoking history. "Even former smokers seem to have more of a pain signal," he said. "You still see a residual effect in former smokers."

He added that he'd be interested to see what happens in the subset of patients with COPD who never smoked. "Dr. Mapel said 16%, and some of the more recent National Health and Nutrition Examination Survey data suggest it's up in the 25% range," Dr. Mannino noted. "And I'd be interested to see if you see a similar pain signal in that group. I suspect you wouldn't."

Dr. Mapel said that healthcare providers need to focus on patients who are in pain. Such patients are more likely to be readmitted to a hospital and have other bad outcomes. "I think it's been overlooked and ignored as an important comorbidity," he said.

From an associated analysis, Dr. Mapel added that patients with COPD in chronic pain have double the healthcare costs of patients without chronic pain, and this fact has important implications for disease management and healthcare spending.

This study was sponsored by Endo Pharmaceuticals. Ms. Roberts disclosed research grant support from GlaxoSmithKline, Boehringer Ingelheim, Endo Pharmaceuticals, and AstraZeneca. Dr. Mapel disclosed grant support from GlaxoSmithKline, Boehringer Ingelheim, AstraZeneca, Ikaria, and Endo. Dr. Mannino disclosed financial relationships with GlaxoSmithKline, Pfizer, Novartis, AstraZeneca, Boehringer Ingelheim, MAP Pharmaceuticals, Dey, and Seprecor.

American Thoracic Society (ATS) 2013 International Conference: Abstract A5703. Presented May 22, 2013.

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