Chronic lung disease (CLD) is one of the most significant variables used by the STS to determine risk for any major adverse outcome following cardiac surgery. The purpose of this study was to determine whether the addition of spirometry measures would provide a better parameter in determining the severity of CLD compared to the STS definitions used to establish the presence and extent of disease based on patient reported medication and/or oxygen usage.
A prospectively blinded study using a convenience sample of patients who presented for elective or urgent cardiac surgery between Nov 2007 to May 2008 and had either a 10 pack years smoking history, asthma or a persistent cough and who were then referred for a preoperative spirometry test. The spirometry results were entered and compared to the patient self reported use of medication and/or oxygen.
Patients (n=107) were primarily CABG (73.2%), urgent (49.2%) and male (86%). 65/107 (60.7%) patients were classified equivalent to the patient reported STS definitions leaving 41.1% (N=42) misclassified (Table 1). There was an increase in the severity of CLD for 92.9% (39/42) of the misclassified patients when comparing the spirometry results to the patient reported definitions. This misclassification created an underreporting of expected number of adverse outcomes to include death by 2 to 25% depending on the level of misclassification.
The findings of this study suggest that the severity of CLD may be significantly misclassified in patients with either, 10 pack years smoking history, asthma or a persistent cough when not using spirometry. The use of the patient report for medication and/or oxygen usage as the only method to determine CLD for this subgroup of patients may lead to underreporting of the risk for adverse outcomes and can have a significant impact on composite risk stratification scoring for cardiac surgery programs.
Spirometry should be used when calculating the CLD for the predicted risk of adverse outcomes in selected cardiac surgery patients.
Linda Henry, No Financial Disclosure Information; No Product/Research Disclosure Information