Journal Watch—Mortality Studies in Bariatric Surgery Patients

| May 1, 2017

Mortality following bariatric surgery compared to other common operations in Finland during a 5-year period (2009-2013). A nationwide registry study.
Böckelman C, Hahl T, Victorzon M. Obes Surg. 2017 Apr 5. [Epub ahead of print]
Synopsis: A concern regarding the safety of bariatric surgery may explain the fact that only a minor fraction of morbidly obese patients has access to it. This is a population-based, nationwide study reporting 30-day, 90-day, and 1-year mortality rates following bariatric surgery in comparison with mortality rates after other common operations in Finland.
Patients undergoing surgery between January 2009 and December 2013 were included. Data on surgical procedures were obtained from the national hospital discharge registry, and cause of death was obtained from Statistics Finland.

Inclusion criteria were met by 156,536 patients. Of these, 3918 underwent surgery for morbid obesity. Three patients (0.08%) died within 30 days following bariatric surgery. The 30-day mortality rate was lower only following prostatectomy. Compared with bariatric surgery, the hazard ratios (HR) for 1-year postoperative mortality were significantly higher for elective cholecystectomy (HR 2.38, 95% CI 1.39-4.08, p = 0.002), hysterectomy (HR 2.87, 95% CI 1.68-4.92, p < 0.001), knee arthroplasty (HR 2.23, 95% CI 1.31-3.81, p = 0.003), hip arthroplasty (HR 11.7, 95% CI 6.90-19.8, p < 0.001), colorectal resections (HR 27.5, 95% CI 16.2-46, p < 0.001), gastric resection (HR 53.0, 95% CI 30.2-93.2, p < 0.001), gastrectomy (HR 74.7, 95% CI 43.0-130, p < 0.001), and coronary artery bypass grafting (HR 30.7, 95% CI 17.4-54.3, p < 0.001).

The authors concluded that mortality rates following bariatric surgery are low and similar or lower than mortality rates following all other common elective surgeries.
PMID: 28382506

Short- and long-term mortality after bariatric surgery: a systematic review and meta-analysis.
Cardoso L, Rodrigues D, Gomes L, Carrilho F. Diabetes Obes Metab. 2017 Feb 28. [Epub ahead of print]
Synopsis: The objective of this study was to investigate short- (≤30 days) and long-term (≥2 years) all-cause mortality after bariatric surgery among adult patients with obesity.
For short-term mortality, eligible studies were randomized controlled trials (RCTs) reporting perioperative mortality. For long-term mortality, RCTs and observational studies comparing mortality between obese patients after bariatric surgery and non-operated controls were eligible. Random-effects models using a Bayesian or frequentist approach were used to pool the effect estimates of short- and long-term mortality, respectively.
The short-term all-cause mortality based on 38 RCTs involving 4,030 patients was 0.18% (95% CI: 0.04%-0.38%) and was higher for open, 0.31% (95% CI: 0.03%-0.97%), and similar in mixed, 0.17% (95% CI: 0.03%-0.43%), and restrictive surgeries, 0.17% (95% CI: 0.03%-0.45%). For long-term mortality, 12 observational studies involving 27,258 operated patients and 97,154 non-operated obese controls were included. Of these, 8 studies were eligible for the meta-analysis, which showed a reduction of 41% in all-cause mortality (hazard ratio 0.59, 95% CI: 0.52-0.67, P<0.001); additionally, operated patients were 0.42 (95% CI: 0.25-0.72, P<0.001) and 0.47 (95% CI: 0.36-0.63, P<0.001) times as likely as non-operated obese controls to die from cardiovascular diseases and cancer, respectively.
The researchers concluded that bariatric surgery is associated with low short-term mortality and may be associated with long-term reductions in all-cause, cardiovascular, and cancer-related mortality.
PMID: 28244626

Overall and cause-specific mortality after Roux-en-Y gastric bypass surgery: A nationwide cohort study
Gribsholt SB, Thomsen RW, Svensson E, Richelsen B. Surg Obes Relat Dis. 2017;13(4):581–587. Epub 2016 Oct 17.
Synopsis: Few population-based studies provide data on mortality after bariatric surgery. The authors hypothesized that hypoglycemia could be an underdiagnosed cause of death. They conducted a Danish nationwide population-based cohort study to examine perioperative, all-cause, and cause-specific long-term mortality in Roux-en-Y gastric bypass (RYGB) patients versus population comparisons.

The study included all 9,895 patients who underwent RYGB during 2006-2010, and a 1:25 age- and gender-matched comparison cohort (n = 247,366) (0.3% lost to follow up). It compared mortality rates and computed mortality rate ratios (MRR) for all-cause and cause-specific mortality using Cox regression analysis. For deceased RYGB patients (n = 91), the authors conducted a detailed medical record audit.

The perioperative (30-days) mortality after RYGB was .04% (4/9895). After 4.2 years, RYGB-related mortality (deaths due to intestinal obstruction/intra-abdominal leakage) was .15% (16/9895). All-cause mortality was very similar in the 2 cohorts (median age, 40.2 years; 21.7% men): RYGB cohort, .89% (n = 91); comparison cohort, .92% (n = 2204); MRR = 1.03 (95% confidence interval [CI], .84-1.27). Mortality due to suicide (2.78; 95% CI, 1.44-5.33), accidents (2.29; 95% CI, 1.16-4.54), gastrointestinal diseases (2.01; 95% CI, 1.06-3.84), and infectious diseases (1.75; 95% CI, .98-3.17) was higher in the RYGB cohort versus comparison groups, but mortality from cancer was lower (0.43; 95% CI, .27-.70). The authors’ medical record audit indicated that 8% of deaths after RYGB (n = 7) were possibly hypoglycemia related.

They concluded that perioperative mortality after RYGB is low in Denmark, and subsequent all-cause mortality is similar to that of matched comparisons. After RYGB, patients have substantially increased mortality due to external causes such as suicide, accidents, and possibly hypoglycemia.
PMID: 27876334

All-cause and cause-specific mortality associated with bariatric surgery: A review
Adams TD, Mehta TS, Davidson LE, Hunt SC. Curr Atheroscler Rep. 2015;17(12):74.
Synopsis: The question of whether or not nonsurgical intentional or voluntary weight loss results in reduced mortality has been equivocal, with long-term mortality following weight loss being reported as increased, decreased, and not changed. In part, inconsistent results have been attributed to the uncertainty of whether the intentionality of weight loss is accurately reported in large population studies and also that achieving significant and sustained voluntary weight loss in large intervention trials is extremely difficult. Bariatric surgery has generally been free of these conflicts. Patients voluntarily undergo surgery and the resulting weight is typically significant and sustained. These elements, combined with possible non-weight loss-related mechanisms, have resulted in improved comorbidities, which likely contribute to a reduction in long-term mortality. This paper reviews the association between bariatric surgery and long-term mortality. From these studies, the general consensus is that bariatric surgical patients have: 1) significantly reduced long-term all-cause mortality when compared to severely obese non-bariatric surgical control groups; 2) greater mortality when compared to the general population, with the exception of one study; 3) reduced cardiovascular-, stroke-, and cancer-caused mortality when compared to severely obese non-operated controls; and 4) increased risk for externally caused death such as suicide.
PMID: 26496931


Category: Journal Watch, Past Articles

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