Differences in open versus laparoscopic gastric bypass mortality risk using the Obesity Surgery Mortality Risk Score (OS-MRS).

BACKGROUND

The Obesity Surgery Mortality Risk Score (OS-MRS) was developed to ascertain preoperative mortality risk of patients having bariatric surgery. To date there has not been a comparison between open and laparoscopic operations using the OS-MRS.

OBJECTIVE

To determine whether there are differences in mortality risk between open and laparoscopic Roux-en-Y Gastric Bypass (RYGB) using the OS-MRS.

SETTING

Three university-affiliated hospitals.

METHODS

The 90-day mortality of 2467 consecutive patients who had primary open (1574) or laparoscopic (893) RYGB performed by one surgeon was determined. Univariate and multivariate analysis using 5 OS-MRS risk factors including body mass index (BMI) gender, age>45, presence of hypertension and preoperative deep vein thrombosis (DVT) risk was performed in each group. Each patient was placed in 1 of 3 OS-MRS risk classes based on the number of risks: A (0-1), B (2-3), and C (4-5).

RESULTS

Preoperative BMI and DVT risk factors were significantly greater in the open group (OG). Preoperative age was significantly greater in the laparoscopic group (LG). There were significantly more class B and C patients in LG. Ninety-day mortality rates for OG and LG patients were 1.0% and .9%, respectively. Pulmonary embolism was the most common cause of death. All deaths in LG occurred during first 4 years of that experience. Mortality rate by class was A = .1%; B = 1.5%; C = 2.3%. The difference in mortality between class B and C patients was not significant. Univariate analysis in the OG indicated that BMI, age, gender, and DVT risk were significant predictors of mortality. In the LG only BMI and DVT were significant predictors of death. Presence of hypertension was not a significant predictor in either group. Multivariate analysis excluding hypertension found that age was predictive of mortality in the OG while BMI (P = .057) and gender (P = .065) approached statistical significance. Conversely, only BMI was predictive of mortality in the LG with age approaching significance (P = .058). In multivariate analysis DVT risk was not predictive of mortality in either group.

CONCLUSIONS

There are significant differences in the predictive value of the OS-MRS between open and laparoscopic RYGB. Although laparoscopic patients were significantly older versus the open patients, age was not predictive of mortality after laparoscopic RYGB. BMI trended toward increased mortality risk in both groups. Changes in technique and protocol likely contributed toward no mortality during the last 6 years of our laparoscopic experience.