KYOTO, JAPAN—Currently, forced expiratory volume in one second (FEV1) is used to diagnose the stage of chronic obstructive pulmonary disease (COPD) and to predict COPD mortality. However, current research has suggested that it may not be the best criterion. Koichi Nishimura, MD, and colleagues have observed that dyspnea is more accurate than FEV1 in predicting five-year survival in COPD patients.[1]

Dr. Nishimura, a respiratory specialist at Kyoto Katsura Hospital, said, “There are many reports published in the literature suggesting that FEV1 is the best evaluation parameter in COPD. This is the first study to suggest dyspnea as a better parameter, because in most previous cohort studies, dyspnea is not measured at baseline.”

In a five-year, multicenter study, he and his colleagues compared the predictive value of dyspnea and disease severity for five-year survival. Disease severity was defined using the percentage of predicted FEV1, based on the American Thoracic Society (ATS) staging for airway obstruction.

Two hundred twenty-seven patients with COPD were enrolled between 1990 and 1994. Respiratory symptoms, smoking history, and pulmonary function—including FEV1, forced vital capacity, diffusing capacity of the lung for carbon monoxide, residual volume, and total lung capacity—were recorded. Dyspnea was evaluated using a 5-point grading scale (see box). Between 1995 and 1999, eight follow-up meetings evaluated the clinical course and prognosis of the enrolled patients.

Information on 183 patients was available at follow-up. Forty-nine of these patients had died, 22 from COPD or COPD-related illness. According to the ATS staging of disease severity, 42 of the 183 patients had been in stage I at baseline, 59 had been in stage II, and 82 had been in stage III. The number of patients who died in each of these three groups was six, 15, and 28, respectively. The differences in five-year survival among the three groups did not reach significance.

Based on the 5-point dyspnea grading system, 67 of the 183 patients were classified as grade II at baseline, 87 as grade III, 26 as grade IV, and three as grade V. Among these grade levels, seven, 21, 18, and three patients died, respectively; the differences in mortality were highly significant. As a result, categorization by level of dyspnea was a better predictor of outcome than was ATS classification of disease severity based on FEV1.

According to Dr. Nishimura, the level of dyspnea reflects more complete information, including subjective perception of respiratory discomfort. Dyspnea level can be measured easily in a clinical setting and used with FEV1 to evaluate patients with COPD.

Reference
1. Nishimura K, Izumi T, Tsukino M, Oga T. Dyspnea is a better predictor of 5-year survival than airway obstruction in patients with COPD. Chest. 2002;121:1434-1440.

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