Higher BMI Yields Longer Surgeries for Lung Cancer Lobectomy

December 5, 2012
Dave Levitan

Obese lung cancer patients undergoing lobectomy spend more time in the operating room than patients with lower body mass index, according to a new study. BMI was not associated with 30-day mortality or increased length of hospital stay.

Obese lung cancer patients undergoing lobectomy spend more time in the operating room than patients with lower body mass index (BMI), according to a new study. BMI was not associated with 30-day mortality or increased length of hospital stay.

“The data regarding the influence of obesity on postsurgical outcomes have been mixed,” wrote researchers led by Jamii B. St. Julien, MD, of Vanderbilt University Medical Center in Nashville, Tennessee, in Annals of Thoracic Surgery. “Research has shown that obesity increases rates of wound infections and minor wound complications, but has not demonstrated a relationship between obesity and increased risk of severe complications or death.” The new study looked at operative time, as it is a “widely used surrogate measure for resource utilization.”

The study used data from the Society of Thoracic Surgeons Database; it included 19,337 patients with lung cancer who underwent lobectomy between 2006 and 2010. The mean BMI of all patients was 27.3, and 4,898 (25.3%) patients had a BMI of at least 30, which is commonly considered obese.

Multivariate analyses showed that a 10-unit increase in BMI added 7.2 minutes of operating room time (P < .0001); for example, a patient with a BMI of 25 would spent 15 fewer minutes in the operating room than one with a BMI of 45.

The mean operating room time across the entire study population was 240 minutes; the mean length of hospital stay was 6.7 days, and the 30-day mortality rate of the entire cohort was 1.8%. Other factors that added time in the operating room included black race, male sex, preoperative chemotherapy, and several others. Only BMI and mediastinoscopy significantly impacted all three components of total operating room time, including preprocedure, procedure, and postprocedure.

BMI actually had an inverse association with length of hospital stay; every 10-unit BMI increase was associated with a stay decrease of 0.3 days (P < .0001). BMI was not significantly associated with 30-day mortality.

The researchers wrote that the increase in operating room time “could represent a major source of the health care costs that are already known to be higher for obese patients in the United States.” Some studies have suggested a per-minute operating room cost of $62, meaning that every 10-unit increase in BMI is associated with an additional $446 in costs.

“If the prevalence of obesity continues to rise, a greater number of patients undergoing lobectomies for lung cancer will likely be obese,” the authors wrote. “Thus, we have identified a significant source of increased health care costs that must be considered on both a hospital and a national health policy level.”

Study Details

There was a “substantial lack of diversity” within the study, with 87% of patients being white, and only 8% black. The obese patients, with a BMI over 30, were more likely to be younger, black, and former smokers than non-obese patients. Of the total cohort, 47.2% were male, and the average age was 66.7 years; 59.5% were former smokers, compared with 26.5% current smokers and 14% never smokers.

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