The effect of obesity on operating room (OR) utilization in breast surgery.

36 Background: More than one-third of adults in the United States are obese. Studies have shown that obesity-related comorbidities increase health care costs, but the effect of obesity on operating room utilization has not been completely evaluated. The purpose of our study was to examine how operative time (OPT) for common procedures in breast surgery is affected by patient weight. We expected that weight affected OPT more so for extensive procedures, such as axillary lymph node dissection (ALND) and mastectomy, than for minimally invasive procedures, such as lumpectomy and sentinel lymph node biopsy (SLNB).

METHODS: OPT and weight for ten breast surgeries were analyzed from the American College of Surgeons 2010 National Surgical Quality Improvement Project database. Only women were included, and those who underwent additional procedures or had incomplete data were excluded. Patients were divided into three groups based on their weight (<135 lbs, 135-199 lbs, and ≥200 lbs). Using the two-sample t-test, OPT for the procedures was compared among the lowest and highest weight categories. We specifically looked at lumpectomy, lumpectomy plus SLNB, ALND, mastectomy, and modified radical mastectomy (MRM).

RESULTS: In all, 16,077 patients were included in the analysis. When the lowest and highest weight groups (<135 lbs and ≥200 lbs) were compared for all procedures, a significant difference of 13 min was seen (p<0.0001). For these same groups, a significant, but not relevant for scheduling, difference in OPT was noted for lumpectomy alone (37 vs. 41 min, p<0.0001) and lumpectomy plus SLNB (71 vs. 80 min, p<0.0001). However, weight affected ALND and mastectomy more drastically. The difference for lumpectomy plus ALND was 22 min (93 vs. 115 min, p=0.0004), while the differences for simple mastectomy and mastectomy plus SLNB were 24 min (89 vs. 113 min, p<0.0001) and 23 min (102 vs. 125 min, p<0.0001), respectively. In addition, the difference for MRM was 22 min (104 vs. 126 min, p<0.0001).

CONCLUSIONS: Patient weight does significantly affect OPT for lumpectomy and SLNB, but the difference is much greater for ALND, mastectomy, and MRM. Therefore, when scheduling more extensive procedures for obese patients, additional time should be allotted to improve OR utilization.