The definition of chronic lung disease in patients undergoing cardiac surgery: A comparison between the Society of Thoracic Surgeons and the American Thoracic Society/European Respiratory Society Classifications

Aim. Early and late outcomes following cardiac surgery may be adversely affected in patients with chronic lung disease (CLD) and the presence of CLD is definition dependent. The purpose of this study was to compare the Society of Thoracic Surgeons (STS) definitions for CLD to the modified American Thoracic Society (ATS)/European Respiratory Society (ERS) definitions in diagnosing and classifying CLD among a cohort of cardiac surgery patients Methods. A prospectively-designed study whereby high risk patients for CLD presenting for non-emergent cardiac surgery and had a history of asthma, a 10 or more pack year history of smoking or a persistent cough were included. All patients underwent spirometry testing within two weeks of surgery. The presence and severity of CLD was coded two times: 1) STS definitions with spirometry; 2) ATS/ERS guidelines. The rate of misclassification was determined using concordance and discordance rates. Sensitivity analysis of the STS spirometry definitions was calculated against the ATS/ERS definitions and respective classifications. Results. The discordant rate for the STS spirometry driven definitions versus the ATS/ERS definitions was 21%. Forty patients (21%) classified as no CLD by the STS spirometry definition were found to have CLD by the ATS/ERS definition. The STS classification had 68% sensitivity (84/124) when identifying any CLD and only 26% sensitivity (14/54) when identifying moderate CLD. Conclusion. The current STS spirometry driven definitions for CLD did not perform as well as the ATS/ERS definitions in diagnosing and classifying the degree of CLD. Consideration should be given to using the ATS/ERS definitions.