Gender bias in the diagnosis of COPD

COPD is thought to be more prevalent among men than women, a finding usually attributed to higher smoking rates and more frequent occupational exposures of significance for men. However, smoking prevalence has increased among women and there is evidence that women may be more susceptible to the adverse pulmonary function effects of smoking than men. There may also be underdiagnosis and misdiagnosis of COPD in both sexes because objective measures of lung function are underused.

We undertook the present study to determine if there is gender bias in the diagnosis of COPD, such that women are less likely than men to receive a diagnosis of COPD. We also attempted to determine if underuse of lung function measurements was a factor in any bias detected.

We surveyed a random sample of 192 primary-care physicians (96 American and 96 Canadian; 154 men and 38 women) using a hypothetical case presentation and a structured interview. The case of cough and dyspnea in a smoker was presented in six versions differing only in the age and sex of the patient. After presentation of the history and physical findings, physicians were asked to state the most probable diagnosis and to choose the diagnostic studies needed. Physicians were then presented with spirometric findings of moderate or severe obstruction without significant bronchodilator response, and the questions repeated. Finally, the negative outcome of an oral steroid trial was described.

Initially, COPD was given as the most probable diagnosis significantly more often for men than women (58% vs 42%; p < 0.05). The likelihood of a COPD diagnosis increased significantly and initial differences between sexes decreased as objective information was provided. After spirometry, COPD diagnosis rates for men and women were 74% vs 66% (p = not significant); after the steroid trial 85% vs 79% (p = not significant). Only 22% of physicians would have requested spirometry after the initial presentation.

In North America, primary-care physicians underdiagnosed COPD, particularly in women. Spirometry reduces the risk of underdiagnosis and gender bias but is underused.