Reasons for referral for pulmonary function testing: an audit of 4 adult lung function laboratories

Pulmonary function testing (PFT) is an important tool in the diagnosis and management of most respiratory conditions, and appropriate interpretation of test results is a fundamental component of the final report. As part of developing a structured approach to interpretation of PFT results, we wished to characterize primary reasons for referral for testing in a range of PFT laboratories.

Four PFT laboratories (3 public, 1 private) using similar PFT databases participated. Reasons for performance of PFTs were extracted from the databases and analyzed. Over 5,000 consecutive tests were evaluated from each lab.

Identifiable reason for referral was found in 83% of 24,602 test results and categorized. The major categories were follow-up of known respiratory disease (53% of 20,332 tests), investigation of specific symptoms (18%), possible specific lung disease (13%), possible induced lung disease (5%), investigation of lung function in known other diseases (5%), and other miscellaneous reasons (5%). Testing in known disease and/or assessing for PFT change was the primary reason for testing in 60% of tests performed. These data highlight the predominance of ongoing assessment of pulmonary function and the importance of access to previous test results to provide clinically useful test reports. They also emphasize the need for having valid criteria describing what constitutes a real clinical change in the various PFT parameters.

We have found that the majority of PFTs are performed to follow disease progress or response to treatment. This has implications with inter- pretation of test results and the clinical utility of PFT.