Undetected chronic obstructive pulmonary disease and asthma in people over 50 years with persistent cough

Chronic obstructive pulmonary disease (COPD) and asthma are underdiagnosed in primary care.

To determine how often COPD or asthma are present in middle-aged and older patients who consult their GP for persistent cough.

A cross-sectional study in 353 patients older than 50 years, visiting their GP for persistent cough and not known to have COPD or asthma.

General practice in the Netherlands.

All participants underwent extensive diagnostic work-up, including symptoms, signs, spirometry, and body plethysmography. All results were studied by an expert panel to diagnose or exclude COPD and/or asthma. The reproducibility of the panel diagnosis was assessed by calculation of Cohen's kappa statistic in a sample of 41 participants.

Of the 353 participants, 102 (29%, 95% confidence interval [CI] = 24 to 34%) were diagnosed with COPD. In 14 of these 102 participants, both COPD and asthma were diagnosed (4%, 95% CI = 2 to 7%). Asthma (without COPD) was diagnosed in 23 (7%, 95% CI = 4 to 10%) participants. Mean duration of cough was 93 days (median 40 days). The reproducibility of the expert panel was good (Cohen's kappa = 0.90).

In patients aged over 50 years who consult their GP for persistent cough, undetected COPD or asthma is frequently present.