Date Published: October 15, 2018
Publisher: Public Library of Science
Author(s): Guillaume Dupont, Laura Flory, Jérôme Morel, Anne-Claire Lukaszewicz, Arnaud Patoir, Emilie Presles, Guillaume Monneret, Serge Molliex, Aamir Ahmad.
Postoperative lymphopenia has been proposed as a risk factor for postoperative infections but has never been identified as such in a multivariate analysis. Postoperative pneumonia (POP) is one of the most common complications after lung cancer surgery and is associated with a worse outcome. We aimed to evaluate the association between postoperative lymphopenia and POP after lung cancer surgery.
Patients admitted for lung cancer surgery (lobectomy, bilobectomy, or pneumonectomy) aged ≥ 18 years and with no history of an immunosuppressive state were eligible for inclusion. Lymphocyte counts were determined in blood drawn on the day before surgery and at postoperative days 1, 3 and 7. POP diagnosis was based on clinical, biological and radiological data. A logistic regression model adjusted on currently described risk factors for POP was used to explain the onset of this condition.
Two hundred patients were included, of whom 43 (21.5%) developed POP. Preoperative lymphocyte count was 1.8±0.6×109 cells/L and 2.0±0.7×109 cells/L in patients with and without POP, respectively (P = .091). In both groups, the lymphocyte count nadir occurred at postoperative day 1. In multivariate analysis, lymphopenia at postoperative day 1 was significantly associated with increased risk of POP (odds ratio: 2.63, 95% CI [1.03–5.40]). POP rate at postoperative day 7 was higher in patients presenting low lymphocyte counts (≤1.19×109 cells/L) at postoperative day 1 (P = .003).
Our study showed that lymphopenia following lung cancer surgery was maximal at postoperative day 1 and was associated with POP.
Postoperative lymphopenia, reaching a nadir from two hours to two days after surgery, has been described for more than thirty years. As lymphocytes are a major component of infection control, postoperative lymphopenia has been proposed as a risk factor for postoperative infections . However, the studies reporting postoperative lymphopenia were heterogeneous regarding surgical procedures (abdominal, thoracic, neurologic, etc.) or inclusion of patients with cancer, and were restricted to a single center. All included small patient populations and did not take into account the currently recognized risk factors for postoperative infection, thereby creating a confounding effect.
From January 2013 to May 2015, 275 patients were screened, of whom 75 were excluded and 200 were deemed to meet the inclusion criteria (Fig 1).
Our study highlighted in a multivariate analysis that postoperative lymphopenia at day 1 post-surgery is an independent risk factor for the development of pneumonia after elective surgery for lung cancer in multivariate analysis.
Our study showed that a low lymphocyte count at postoperative day 1 was independently associated with the development of pneumonia after lung cancer surgery. These results require to be confirm in a large prospective cohort.