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IIR 05-201 – HSR&D Study

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IIR 05-201
Long-term Outcomes of Bariatric Surgery in the Veterans Health Administration
Matthew L Maciejewski PhD
Durham VA Medical Center, Durham, NC
Durham, NC
Funding Period: July 2006 - March 2010

BACKGROUND/RATIONALE:
Between 1986 and 2005, the prevalence of morbid obesity (body mass index (BMI) >= 35) in the United States rose from 0.8% to 8.5%. This epidemic has adverse impacts on morbidity, mortality and health care expenditures. Bariatric surgery has been shown to be the most effective therapy for promoting clinically significant weight loss and improving obesity-associated comorbidities among adults with a BMI >= 40.

The current evidence base for bariatric surgery might not apply to the older, predominantly male population found in the VA because studies have primarily included young female patients. Male patients and those with advanced age may be at greater risk for severe, life-threatening complications of bariatric surgery, and the evidence base for the appropriate use of bariatric surgery in those patients needs to be better understood. Over the past decade, VHA has provided bariatric surgery to over 1000 severely obese veterans in 12 approved VHA Medical Centers in the hopes of improving their body weight, health, and longevity, and potentially also reducing their health care expenditures. As bariatric surgery became more fully integrated into the MOVE! program in 2007 and additional bariatric surgical centers are opened in the future, it is critically important to evaluate the impact of bariatric surgery on veteran and health system outcomes.

OBJECTIVE(S):
The purpose of the study was to compare the survival rates, health care use, and expenditures of morbidly obese veterans who had bariatric surgery in VA medical centers from 2000 to 2006 with those of a cohort of morbidly obese veterans who did not have surgery. We also identified the patient-level predictors of survival, preoperative and postoperative health care use, and expenditures among veterans who had bariatric surgery in VA. With short-term project funding (SHP 08-137), we also examined medication discontinuation and weight change at one year among veterans who had bariatric surgery in VA.

METHODS:
Using multiple VA administrative claims data collected between FY99 and FY06, we constructed survival, health care use, and expenditure outcomes for veterans who had bariatric surgery in VA and veterans who did not have surgery. We identified 888 surgical cases from the National Surgical Quality Improvement Program (NSQIP) database, and included various subsets in the survival (n=856) and utilization/expenditure (n=845) analyses of the surgical cohort. Survival was identified from the mini-Vitals dataset, health care utilization and expenditures were identified from Health Economics Resource Center (HERC) Average Cost Datasets, and patient covariates were obtained from NSQIP, Outpatient Care File and Patient Treatment File datasets. We controlled for comorbidity burden via the Diagnostic Cost Group risk adjuster. Survival of the surgical cases was estimated using a Cox proportional survival model, VA utilization was estimated using count data (e.g., negative binomial or Poisson) regression models, and VA expenditures were estimated using one-part or two-part generalized estimating equations. Adjusted comparisons of survival and VA utilization/expenditures, and weight change between surgical cases and non-surgical controls, is ongoing.

FINDINGS/RESULTS:
In a published study of the cohort of 856 veterans who had bariatric surgery in 2000-2006 in 12 VA approved bariatric surgical centers, we found that 30-day, 90-day and 1-year mortality rates were 1.3%, 2.1%, and 3.4%. Veterans were at greater risk of death if they had a BMI >= 50 or had greater overall disease burden (as measured by the DCG score>2).

In a manuscript in press at Medical Care, we found that health care utilization and expenditures of 846 veterans in the three years after surgery are similar to those in the three years before surgery. In a second manuscript in press at Surgery for Obesity and Related Disorders, we found that 52% of veterans with diabetes taking oral agents or insulin were able discontinue their diabetes medications within a year of surgery, and that 40% of veterans with hyperlipidemia taking lipid-lowering medications were able to discontinue their medications at one year. In completed analyses that are currently being drafted into a manuscript, we found that veterans achieve substantial weight loss at one year (31% of baseline weight and an average of 106 pounds), but weight regain after 2 years appears common (average weight regain of 36 pounds). Finally, we are finding in ongoing work that surgical cases are statistically different from non-surgical controls in all observed covariates and that bariatric surgery confers a statistically significant protective benefit against mortality at nine years.

IMPACT:
This study provides a rigorous assessment of veterans who have undergone bariatric surgery from 2000 to 2006, to establish an evidence base for the health and economic impacts of bariatric surgery for morbidly obese veterans. Results of this study are relevant to patient care in the VA and will assist the VA in meeting three major objectives: 1) improving the generalizability and specificity of recommendations in the VA Obesity Clinical Practice Guideline, 2) improving bariatric surgical practice in coordination with the VA Bariatric Surgery Workgroup, and 3) refining the evidence base for the application of surgical treatment in the national VA Managing Obesity for Veterans Everywhere (MOVE!) program. This study also provides the most rigorous evidence of the health and economic benefits of bariatric surgery for older male patients and will be the first analyses to compare cases and matched controls in a predominantly male sample.

PUBLICATIONS:

Journal Articles

  1. Arterburn D, Livingston EH, Olsen MK, Smith VA, Kavee AL, Kahwati LC, Henderson WG, Maciejewski ML. Predictors of initial weight loss after gastric bypass surgery in twelve Veterans Affairs Medical Centers. Obesity research & clinical practice. 2013 Sep 1; 7(5):e367-76.
  2. Worni M, Guller U, Maciejewski ML, Curtis LH, Gandhi M, Pietrobon R, Jacobs DO, Østbye T. Racial differences among patients undergoing laparoscopic gastric bypass surgery: a population-based trend analysis from 2002 to 2008. Obesity surgery. 2013 Feb 1; 23(2):226-33.
  3. Maciejewski ML, Winegar DA, Farley JF, Wolfe BM, DeMaria EJ. Risk stratification of serious adverse events after gastric bypass in the Bariatric Outcomes Longitudinal Database. Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery. 2012 Nov 1; 8(6):671-7.
  4. Maciejewski ML, Livingston EH, Smith VA, Kavee AL, Kahwati LC, Henderson WG, Arterburn DE. Survival among high-risk patients after bariatric surgery. JAMA. 2011 Jun 15; 305(23):2419-26.
  5. Maciejewski ML, Smith VA, Livingston EH, Kavee AL, Kahwati LC, Henderson WG, Arterburn DE. Health care utilization and expenditure changes associated with bariatric surgery. Medical care. 2010 Nov 1; 48(11):989-98.
  6. Arterburn D, Livingston EH, Schifftner T, Kahwati LC, Henderson WG, Maciejewski ML. Predictors of long-term mortality after bariatric surgery performed in Veterans Affairs medical centers. Archives of surgery (Chicago, Ill. : 1960). 2009 Oct 1; 144(10):914-20.
Conference Presentations

  1. Maciejewski ML, Smith V, Livingston E, Kahwati L, Kavee AL, Arterburn DE. Post-Surgical Health Care Expenditures and Weight Change Following Bariatric Surgery. Paper presented at: AcademyHealth Annual Research Meeting; 2010 Jun 28; Boston, MA.
  2. Maciejewski ML, Smith V, Livingston E, Kahwati L, Henderson WG, Kavee AL, Arterburn DE. Post-Surgical Health Care Expenditures and Weight Change Following Bariatric Surgery. Paper presented at: Society of General Internal Medicine Annual Meeting; 2010 Apr 30; Minneapolis, MN.
  3. Maciejewski ML, Arterburn D, Livingston E, Kahwati L, Olsen MK, Kavee AL, Bryson C. Survival, Weight Change & Medication Discontinuation of Veterans Undergoing Bariatric Surgery in VA. Poster session presented at: AcademyHealth Annual Research Meeting; 2009 Jun 28; Washington, DC.
  4. Maciejewski ML, Arterburn DE, Livingston E, Henderson WG, Kahwati L, Kavee AL. Predictors of Long-Term Mortality Following Bariatric Surgery in Veterans Affairs Medical Centers. Paper presented at: AcademyHealth Annual Research Meeting; 2008 Jun 8; Washington, DC.


DRA: Health Systems
DRE: Treatment - Observational
Keywords: Obesity, Outcomes, Quality assessment
MeSH Terms: Outcome Assessment (Health Care)

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