The impact of marginal lung function on outcomes in the era of minimally invasive thoracic surgery

BACKGROUND: The effect of marginal lung function on outcomes after lung resection has traditionally been studied in the context of open thoracic surgery. Its impact on postoperative outcomes in the era of minimally invasive lung resection is unclear. METHODS: In this retrospective cohort study, we included adult patients who underwent minimally invasive lung resection at our institution between January 2017 and May 2020 for known malignancy or lung nodule. Marginal lung function was defined as pre-operative forced expiratory volume in 1 second (FEV1) and/or diffusion lung capacity of carbon monoxide <60% of predicted. Our outcomes included a composite outcome of pulmonary morbidity and/or 30- and 90-day mortality, and hospital length of stay. We used multivariable logistic and Poisson regression models to identify associations with outcomes, and Kaplan-Meier and Cox models to estimate survival. RESULTS: Of 300 patients, 88 (29%) had marginal lung function. Patients in the marginal group were more likely to be female (69% vs. 56%; P=0.028), and more likely to have: hypertension (HTN) (83% vs. 71%; P=0.028), chronic obstructive pulmonary disease (COPD) (38% vs. 12%; P<0.001), interstitial lung disease (ILD) (9% vs. 3%; P<0.019), and ischemic heart disease (28% vs. 18%; P=0.033). Patients were similar in terms of age (68±8 vs. 68±10 years; P=0.932), and other comorbidities. Anatomic lung resection comprised 56.8% of the marginal group vs. 74% in the non-marginal group (P=0.003). The most common complication was prolonged air leak (18.2% vs. 11.8%; P=0.479). Marginal lung function had a trend toward increased composite respiratory complications (22.7% vs. 15.1%; P=0.112) and 90-day mortality (5.7% vs. 4.2%; P=0.591), although they did not reach statistical significance. There was a statistically significant 1-day average increase in length of stay in the marginal lung function cohort (4.6 vs. 3.4 days; P<0.015) with a stronger association with diffusion lung capacity of carbon monoxide than FEV1. Survival was similar (marginal function HR =1.0; P=0.994). CONCLUSIONS: In the era of minimally invasive thoracic surgery, lung resection in patients with marginal lung function may be considered in select patients. These findings aid in the selection consideration and counseling of this patient population.