A Modified Calculation Improves the Accuracy of Predicted Postoperative Lung Function Values in Lung Cancer Patients

Abstract

Purpose Preoperative pulmonary function testing is mandatory for non-small cell lung cancer (NSCLC) surgery. The predicted postoperative FEV1 (ppoFEV1) is used for further risk stratification. We compared the ppoFEV1 with the postoperative FEV1 (postFEV1) in order to improve the calculation of the ppoFEV1. Methods 87 patients voluntarily received an FEV1 assessment 1 year after surgery. ppoFEV1 was calculated according to the Brunelli calculation. Baseline characteristics and surgical procedure were compared in a uni- and multivariate analysis between different accuracy levels of the ppoFEV1. Parameters which remained significant in the multinominal regression analysis were evaluated for a modification of the ppoFEV1 calculation. Results Independent factors for a more inaccurate ppoFEV1 were preoperative active smoking (odds ratio (OR) 4.1, confidence interval (CI) 3.6–6.41; p = 0.01), packyears (OR 4.1, CI 3.6–6.41; p = 0.008), younger age (OR 1.1, CI 1.01–1.12; p = 0.03), and patients undergoing pneumectomy (OR 5.55, CI 1.35–23.6; p = 0.01). For the customized ppoFEV1 we excluded pneumonectomies. For patients < 60 years, an additional lung segment was added to the calculation. ppoFEV1 = preFEV1 × $$1-\left(\frac{\text{Lung segments resected} + 1}{\text{Total number of segments}}\right)$$ 1 - Lung segments resected + 1 Total number of segments . For actively smoking patients with more than 30 packyears we subtracted one lung segment from the calculation ppoFEV1 = PreFEV1 × $$1-\left(\frac{\text{Lung segments resected} - 1}{\text{Total number of segments}}\right)$$ 1 - Lung segments resected - 1 Total number of segments . Conclusion We were able to enhance the predictability of the ppoFEV1 with modifications. The modified ppoFEV1 (1.828 l ± 0.479 l) closely approximates the postFEV1 of 1.823 l ± 0.476 l, (0.27%) while the original ppoFEV1 calculation is at 1.78 l ± 0.53 (2.19%). However, if patients require pneumectomy, more complex techniques to determine the ppoFEV1 should be included to stratify risk.

A comparative study of four thoracic mortality scores

“…5 In this context, risk prediction models are increasingly crucial for preoperative risk stratification and assessing the quality of surgery. These risk stratification models range from straightforward additive calculations such as the predicted postoperative FEV1 (ppoFEV1) or modified forms of the ppoFEV1 6 to very elaborate logarithmic scoring systems. The four to this date most established and most widely used scoring models are the Throacoscore by Falcoz et al 2007, 7 the Epithor by Bernard et al 2011, 8 Eurolung 2 by Brunelli et al, 9 and the simplified Eurolung 2 by Brunelli et al, 10 which we will call Eurolung 2b for simplification in this paper.…”