Use the Lower Limit of Normal, Not 80% Predicted, in Judging Eligibility for Lung Resection

Background: Impaired lung function (LF) is a well-known risk factor for perioperative complications in patients qualified for lung resection surgery. The recent European guidelines recommend using values below 80% predicted as indicating abnormal LF rather than the lower limit of normal (LLN). Objectives: To assess how the choice of a cut-off point (80% predicted vs. LLN at -1.645 SD) affects the incidence of functional disorders and postoperative complications in lung cancer patients referred for lung resection. Methods: Preoperative spirometry and the transfer factor for carbon monoxide (TL,CO) were retrospectively analysed in 851 consecutive lung cancer patients after resectional surgery. Results: Airway obstruction was diagnosed in 369 (43.4%), and a restrictive pattern in 41 patients (4.8%). The forced expiratory volume in 1 s (FEV1) or TL,CO was below the LLN in 503 patients (59.1%), whereas the FEV1 or TL,CO was <80% predicted in 620 patients (72.9%; χ2 test: p < 0.0001). In all, 117 out of 851 patients had LF indices <80% predicted but not below the LLN. Odds ratios (ORs) for perioperative complications were higher in patients with impaired LF indices defined as below the LLN (1.59, p = 0.0005) with the exception of large resections (>5 segments). In patients with test results above the LLN and <80% predicted, the OR for perioperative complications was not different (1.14, p = 0.5) from that in patients with normal LF. Conclusions: LF impairments are common in candidates for lung resection. Using the LLN instead of 80% predicted diminishes the prevalence of respiratory impairment by 14% and allows for safe resectional surgery without additional function testing.

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