Predicting 90-day mortality after bariatric surgery: an independent, external validation of the OS-MRS prognostic risk score

Predicting serious complication risks after bariatric surgery: external validation of the Michigan Bariatric Surgery Collaborative risk prediction model using the Dutch Audit for Treatment of Obesity

BACKGROUND

Risk-prediction tools can support doctor-patient (shared) decision making in clinical practice by providing information on complication risks for different types of bariatric surgery. However, external validation is imperative to ensure the generalizability of predictions in a new patient population.

OBJECTIVE

To perform an external validation of the risk-prediction model for serious complications from the Michigan Bariatric Surgery Collaborative (MBSC) for Dutch bariatric patients using the nationwide Dutch Audit for Treatment of Obesity (DATO).

SETTING

Population-based study, including all 18 hospitals performing bariatric surgery in the Netherlands.

METHODS

All patients registered in the DATO undergoing bariatric surgery between 2015 and 2020 were included as the validation cohort. Serious complications included, among others, abdominal abscess, bowel obstruction, leak, and bleeding. Three risk-prediction models were validated: (1) the original MBSC model from 2011, (2) the original MBSC model including the same variables but updated to more recent patients (2015-2020), and (3) the current MBSC model. The following predictors from the MBSC model were available in the DATO: age, sex, procedure type, cardiovascular disease, and pulmonary disease. Model performance was determined using the area under the curve (AUC) to assess discrimination (i.e., the ability to distinguish patients with events from those without events) and a graphical plot to assess calibration (i.e., whether the predicted absolute risk for patients was similar to the observed prevalence of the outcome).

RESULTS

The DATO validation cohort included 51,291 patients. Overall, 986 patients (1.92%) experienced serious complications. The original MBSC model, which was extended with the predictors "GERD (yes/no)," "OSAS (yes/no)," "hypertension (yes/no)," and "renal disease (yes/no)," showed the best validation results. This model had a good calibration and an AUC of .602 compared with an AUC of .65 and moderate to good calibration in the Michigan model.

CONCLUSION

The DATO prediction model has good calibration but moderate discrimination. To be used in clinical practice, good calibration is essential to accurately predict individual risks in a real-world setting. Therefore, this model could provide valuable information for bariatric surgeons as part of shared decision making in daily practice.

The Bariatric Experience Long Term (BELONG): Factors Related to Having Bariatric Surgery in a Large Integrated Healthcare System

PURPOSE

Bariatric surgery is the most effective treatment for severe obesity, but currently, only 1-2% of all eligible patients undergo surgery each year. This study examined which factors were associated with a patient receiving bariatric surgery after referral in a real-world healthcare setting.

MATERIALS AND METHODS

The current study used the baseline survey and electronic medical record (EMR) data from the Bariatric Experience Long Term (BELONG) study (n = 1975). Predictors of who did (n = 1680) and who did not (n = 295) have surgery were analyzed using multivariate logistic regression.

RESULTS

Participants (n = 1975; 42.4% response rate) were primarily women (84%) and either non-Hispanic Black or Hispanic (60%). In the fully adjusted multivariate model, the strongest predictors of having surgery were being a woman (OR = 3.17; 95% CI = 2.15, 4.68; p < .001) and losing at least 5% of their body weight in the year before surgery (OR = 3.16; 95% CI = 2.28, 4.38; p < .001). The strongest predictors of not having surgery were a ≥ BMI 50 kg/m2 (OR = .39; 95% CI = .27, .56; p < .001) and having a higher physical comorbidity burden (OR = .84; 95% CI = .75, .94; p = .004).

CONCLUSIONS

Practices such as 5-10% total weight loss before surgery and selection of patients with safer operative risk profiles (younger with lower comorbidity burden) may inadvertently contribute to under-utilization of bariatric surgery among some demographic subpopulations who could most benefit from this intervention.

Safety and Effectiveness of Longer-Term Phentermine Use: Clinical Outcomes from an Electronic Health Record Cohort

OBJECTIVE

The aim of this work was to study weight loss and risk of cardiovascular disease (CVD) or death associated with longer-term phentermine use.

METHODS

Using electronic health record data, 13,972 adults were identified with a first phentermine fill in 2010 to 2015, creating exposure categories according to a patient's duration of use (referent: ≤ 3 months). Multivariable linear models were used to compare percent weight loss across categories at 6, 12, and 24 months, and Cox proportional hazards models were used to compare risk of composite CVD or death, up to 3 years after starting phentermine.

RESULTS

The cohort was 84% female and 45% white, with a mean (SD) baseline age 43.5 (10.7) years and BMI of 37.8 (7.2) kg/m² . In multivariable models, longer-term users of phentermine experienced more weight loss; patients using continuously for > 12 months lost 7.4% more than the referent group at 24 months (P < 0.001). The composite CVD or death outcome was rare (0.3%, 41 events), with no significant difference in hazard ratios between groups.

CONCLUSIONS

Greater weight loss without increased risk of incident CVD or death was observed in patients using phentermine monotherapy for longer than 3 months. Despite the limitations of the observational design, this study supports the effectiveness and safety of longer-term phentermine use for low-risk individuals.

Association Between Bariatric Surgery and Macrovascular Disease Outcomes in Patients With Type 2 Diabetes and Severe Obesity

IMPORTANCE

Macrovascular disease is a leading cause of morbidity and mortality for patients with type 2 diabetes, and medical management, including lifestyle changes, may not be successful at lowering risk.

OBJECTIVE

To investigate the relationship between bariatric surgery and incident macrovascular (coronary artery disease and cerebrovascular diseases) events in patients with severe obesity and type 2 diabetes.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective, matched cohort study, patients with severe obesity (body mass index ≥35) aged 19 to 79 years with diabetes who underwent bariatric surgery from 2005 to 2011 in 4 integrated health systems in the United States (n = 5301) were matched to 14 934 control patients on site, age, sex, body mass index, hemoglobin A1c, insulin use, observed diabetes duration, and prior health care utilization, with follow-up through September 2015.

EXPOSURES

Bariatric procedures (76% Roux-en-Y gastric bypass, 17% sleeve gastrectomy, and 7% adjustable gastric banding) were compared with usual care for diabetes.

MAIN OUTCOMES AND MEASURES

Multivariable-adjusted Cox regression analysis investigated time to incident macrovascular disease (defined as first occurrence of coronary artery disease [acute myocardial infarction, unstable angina, percutaneous coronary intervention, or coronary artery bypass grafting] or cerebrovascular events [ischemic stroke, hemorrhagic stroke, carotid stenting, or carotid endarterectomy]). Secondary outcomes included coronary artery disease and cerebrovascular outcomes separately.

RESULTS

Among a combined 20 235 surgical and nonsurgical patients, the mean (SD) age was 50 (10) years; 76% of the surgical and 75% of the nonsurgical patients were female; and the baseline mean (SD) body mass index was 44.7 (6.9) and 43.8 (6.7) in the surgical and nonsurgical groups, respectively. At the end of the study period, there were 106 macrovascular events in surgical patients (including 37 cerebrovascular and 78 coronary artery events over a median of 4.7 years; interquartile range, 3.2-6.2 years) and 596 events in the matched control patients (including 227 cerebrovascular and 398 coronary artery events over a median of 4.6 years; interquartile range, 3.1-6.1 years). Bariatric surgery was associated with a lower composite incidence of macrovascular events at 5 years (2.1% in the surgical group vs 4.3% in the nonsurgical group; hazard ratio, 0.60 [95% CI, 0.42-0.86]), as well as a lower incidence of coronary artery disease (1.6% in the surgical group vs 2.8% in the nonsurgical group; hazard ratio, 0.64 [95% CI, 0.42-0.99]). The incidence of cerebrovascular disease was not significantly different between groups at 5 years (0.7% in the surgical group vs 1.7% in the nonsurgical group; hazard ratio, 0.69 [95% CI, 0.38-1.25]).

CONCLUSIONS AND RELEVANCE

In this observational study of patients with type 2 diabetes and severe obesity who underwent surgery, compared with those who did not undergo surgery, bariatric surgery was associated with a lower risk of macrovascular outcomes. The findings require confirmation in randomized clinical trials. Health care professionals should engage patients with severe obesity and type 2 diabetes in a shared decision making conversation about the potential role of bariatric surgery in the prevention of macrovascular events.

Preoperative immobility significantly impacts the risk of postoperative complications in bariatric surgery patients

BACKGROUND

Preoperative immobility in general surgery patients has been associated with an increased risk of postoperative complications. It is unknown if immobility affects bariatric surgery outcomes.

OBJECTIVES

The aim of this study was to determine the impact of immobility on 30-day postoperative bariatric surgery outcomes.

SETTING

This study took place at a university hospital in the United States.

METHODS

The Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program 2015 data set was queried for primary minimally invasive bariatric procedures. Preoperative immobility was defined as limited ambulation most or all the time. Logistic regression analysis was performed to determine if immobile patients are at increased risk (odds ratio [OR]) for 30-day complications.

RESULTS

There were 148,710 primary minimally invasive bariatric procedures in 2015. Immobile patients had an increased risk of mortality (OR 4.59, P<.001) and greater operative times, length of stay, reoperation rates, and readmissions. Immobile patients had a greater risk of multiple complications, including acute renal failure (OR 6.42, P<.001), pulmonary embolism (OR 2.44, P = .01), cardiac arrest (OR 2.81, P = .05), and septic shock (OR 2.78, P = .02). Regardless of procedure type, immobile patients had a higher incidence of perioperative morbidity compared with ambulatory patients.

CONCLUSIONS

This study is the first to specifically assess the impact of immobility on 30-day bariatric surgery outcomes. Immobile patients have a significantly increased risk of morbidity and mortality. This study provides an opportunity for the development of multiple quality initiatives to improve the safety and perioperative complication profile for immobile patients undergoing bariatric surgery.

Failure of the Obesity Surgery Mortality Risk Score (OS-MRS) to Predict Postoperative Complications After Bariatric Surgery. A Single-Center Series and Systematic Review

BACKGROUND

The obesity surgery mortality risk score (OS-MRS) was developed to determine the risk of postoperative mortality in patients undergoing bariatric surgery. The aim of the present study is to assess the utility of this score for preventing the risk of postoperative complications from bariatric surgery.

METHODS

Prospective study of 321 patients undergoing bariatric surgery to whom the OS-MRS was applied. Postoperative complications were classified according to the Clavien-Dindo system. The relation between the OS-MRS and the appearance of complications and mortality was analyzed. A Medline/Embase search was conducted using bariatric surgery, mortality, and complications as key words. Studies using the OS-MRS to predict morbidity and mortality were included.

RESULTS

Of the 321 patients, 303 (94.3%) underwent gastric bypass and the remaining 18 (5.6%) a sleeve gastrectomy. The OS-MRS classified 178 patients as class A (55.5%), 129 as class B (40.2%), and 14 as class C (4.4%). According to the Clavien-Dindo system, 10.4% of the complications were ≥III. There was one death (class B). No significant association was found between the OS-MRS and the rate of complications.

CONCLUSIONS

In our study, the OS-MRS is not correlated with the appearance of early complications or mortality. Future studies must focus on systems for predicting the appearance and severity of postoperative complications classified according to the Clavien-Dindo system, and not only on mortality.

[Quality indicators for metabolic and bariatric surgery in Germany : Evidence-based development of an indicator panel for the quality of results, indications and structure]

An expert committee was appointed by the German Society for General and Visceral Surgery to develop a panel of appropriate quality indicators to collate the quality of results, indications and structure in metabolic and bariatric surgery. This entailed assimilating the available evidence (systematic literature search), results from the national registry of the society (StuDoQ|MBE) and specific socioeconomic aspects (e. g. severely limited access to metabolic and bariatric surgery in Germany). These quality parameters were to be incorporated into the national guidelines and the rules of procedure for certification in the future. The committee concluded that mortality, MTL30 and severe complications needing intervention (Clavien-Dindo ≥ 3b) are suitable indicators to measure surgical outcome quality due to their relevance, scientific soundness and practicability. As a systematic follow-up is mandatory after bariatric surgery, a minimum follow-up quota is now required using reported quality of life data as an indicator of process quality. As intestinal bypass procedures have been shown to be superior in the treatment of type 2 diabetes, these procedures should be offered to eligible patients and also be performed. The proposed threshold values based on the results of the available literature and StuDoQ registry are to be considered as preliminary and need to be validated and adjusted if necessary in the future. The StuDoQ|MBE is considered a valuable tool to gather this information and also represents the appropriate infrastructure for the collation of relevant risk adjustors.

Surgical Management of Metabolic Syndrome Related to Morbid Obesity

Current treatment approaches in morbid obesity are multimodal in nature. Combination therapies include increases in moderate-intensity aerobic and resistance exercise; behavioral lifestyle changes to increase compliance with diet and activity recommendations; medical nutrition therapy; intensive medical therapy; and metabolic surgical procedures, such as gastric bypass and vertical sleeve gastrectomy. This article focuses on the preoperative evaluation and proper patient selection for metabolic surgery. The procedures are discussed relative to their anatomy, metabolic mechanism of action, and common adverse effects.