Difficulties in the interpretation of lung function tests in the diagnosis of asthma and chronic obstructive pulmonary disease.

Objective: To ascertain differences in the interpretation of spirometry and peak flow measurement between primary care (several practioners and nurses) and specialists in patients with a pre-existing diagnosis of asthma and chronic obstructive pulmonary disease (COPD).

Design: A randomized, prospective cohort study of 98 patients with a pre-existing diagnosis of asthma or COPD. Two chest specialists independently interpreted the peak flow and spirometric data and they were also blinded to the primary care results.