Family Physicians Skip Lung Function Test in Diagnosing COPD

HINES, Ill., June 16 - Family physicians may be diagnosing chronic obstructive pulmonary disease (COPD) overly hastily, evaluating only symptoms and smoking history without the recommend spirometry, according to researchers here.

About two-thirds of patients newly diagnosed with COPD never received spirometry testing, reported Todd A. Lee, PharmD, Ph.D., of the Hines Veterans Affairs hospital here, and colleagues in the June issue of the journal Chest.

While many of these patients may indeed have COPD, there is no way to know for sure without a lung function test, said Dr. Lee. "As a result, patients who do not have COPD may be receiving unnecessary chronic therapy."

The investigators examined the medical records of nearly 200,000 patients in the Veterans Health Administration (VHA) health-care system diagnosed with COPD from October 1998 to September 1999. Nearly all the patients were male (98%), and their average age was 67.5. More than 95% had been diagnosed by a family physician during an outpatient visit.

However, only about 67,000 of study patients (33.7%) underwent spirometry, either at the family physician's clinic or after being referred to a pulmonary clinic, the study found.

Increasing age was associated with decreasing likelihood of receiving the lung function test. Compared with patients in their 40s, those in their 60s were 18% less likely to have been tested (odds ratio=0.82; 95% confidence interval=0.78 to 0.86), those in their 70s were 32% less likely (OR=0.68; 95% CI=0.65 to 0.71), and those in their 80s were 48% less likely (OR=0.52; 95% CI=0.49 to 0.55).

"Providers may be more reluctant to use spirometry in older patients because of concerns about the validity and acceptability of the test results," Dr. Lee said.

However, no studies in the literature suggest that age alone is a risk factor for "bad" spirometry or should exclude patients from undergoing the test, the authors said.

Among patients who suffered an acute exacerbation of COPD, only about 21% underwent spirometry afterward, the study found. This despite current guidelines recommending the test four to six weeks after an exacerbation, Dr. Lee said. Physicians may be unsure of the utility of spirometry following exacerbations, the authors suggested.

As expected, patients referred for a pulmonary clinic visit were more likely to have undergone spirometry (OR=3.29; 95% CI=3.21 to 3.27). However, "these patients are also probably more likely to have more severe COPD if they require referral and treatment in pulmonary clinics," the authors said.

As expected, more patients undergoing surgery for any reason (85%) received the lung function test. The test helps surgeons decide how well the patient will tolerate general anesthesia and the surgical procedure, the authors said.

Overall, the study "raises questions about how COPD is being diagnosed in patients who are treated in general medicine clinics and whether patients who are identified with only a diagnostic code actually have the disease," the authors said.

COPD is frequently said to be an under-diagnosed and under-treated disease, but without diagnoses based on spirometry, one simply can't know how under- or over-diagnosed the disease really is, the authors said.

"There are advocates for the use of spirometry by providers in general medicine clinics for the diagnosis of COPD. However, some research suggests that the quality of spirometry in this setting may be suboptimal," ` the authors said.

"Within the VHA health-care system, spirometry is almost always performed in pulmonary function laboratories and not in general medicine clinics," they added, "a situation that may differ from that in many health-care systems."

Guidelines from the American Thoracic Society, the European Respiratory Society, and the Global Initiative for Chronic Obstructive Lung Disease all indicate spirometry is necessary to diagnose COPD, the authors said.