How often is diagnosis of COPD confirmed with spirometry?

Chronic obstructive pulmonary disease (COPD) is an important cause of morbidity and mortality worldwide. Diagnosis is customarily confirmed with spirometry, but there are few studies on documented spirometry use in everyday clinical practice.

In a cross-sectional survey and study of the medical records of primary and secondary care COPD patients aged 18-75 in a Swedish region, patients with COPD were randomly selected from the registers of 56 primary care centres and 14 hospital outpatient clinics. Spirometry data at diagnosis +/-6 months were analyzed.

From 1114 patients with COPD, 533 with a new diagnosis of COPD during the four-year study period were identified. In 59% (n=316), spirometry data in connection with diagnosis were found in the medical records. Spirometry data with post-bronchodilator forced expiratory volume in 1s (FEV(1))/ vital capacity (VC) ratios were available in 45% (n=241). FEV1/VC ratio <0.70 were found in 160 patients, which corresponds to 30% of the patients with a new diagnosis. Lower age, female gender, current smoking, higher body mass index (BMI) and shorter forced exhalation time were related to COPD diagnosis despite an FEV(1)/VC ratio of >/=0.70. The most common problem in the quality assessment was an insufficient exhalation time.

Only a third of Swedish patients with COPD had their diagnosis confirmed with spirometry. Our data indicate that female gender, current smoking, higher BMI and short exhalation time increase the risk of being diagnosed with COPD without fulfilling the spirometric criteria for the disease.