We assessed the prevalence of gastric bypass surgeries in the United States on the basis of data from the 1998 to 2002 National Hospital Discharge Survey. Between 1998 and 2002, rates (per 100 000 adults) increased significantly (P<.001): from 7.0 to 38.6. This observed increase in the rate of gastric bypass surgery for the treatment of obesity may be attributed in part to improvements in surgical technique, improved patient outcomes, and increased popularity of this procedure.

The prevalence of obesity in the US population continues to increase, making obesity a major public health concern.14 Bariatric surgery has become a popular method of treating obesity, with gastric bypass surgery emerging as the most widely used of these surgical procedures.58

We used the National Hospital Discharge Survey, an annual probability sample of discharged patients from nonfederal, short-stay (average length of stay of fewer than 30 days), noninstitutional hospitals in the United States, to examine annual rates and patient characteristics associated with the gastric bypass procedure from 1998 to 2002. A detailed description of the sample design and data collection method of the National Hospital Discharge Survey has been published in detail elsewhere.9

Diagnoses and procedures in the National Hospital Discharge Survey were coded according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM ).10 Gastric bypass was defined as the presence of an ICD-9-CM procedure code of 44.31 or 44.39, corresponding to the Roux-en-Y procedure, and all other bypass procedures. Obese and morbidly obese patients were identified by the presence of accompanying ICD-9-CM diagnostic codes 278.01, 278.00, 278.0, 278.1, or 278.8. Patients with diagnosis codes corresponding to abdominal neoplasm and other malignant neoplasm were excluded from analysis (codes 150.0 through 159.9, inclusive).

Diagnoses corresponding to selected independent predictors in the Charlson Comorbidity Index were used to measure the burden of comorbid disease in our sample. The specific diagnoses summarized are those for myocardial infarction, congestive heart failure, peripheral vascular disease, dementia, cerebrovascular disease, chronic pulmonary disease, connective tissue disease, ulcer disease, mild liver disease, hemiplegia, moderate to severe renal disease, diabetes, moderate to severe liver disease, and metastatic solid tumor.11,12

The estimated annual number of gastric bypass procedures was derived from the sampling weights provided with the National Hospital Discharge Survey. Annual population rates were calculated by using the adjusted adult (aged 18 years or older) civilian population of the United States in each corresponding survey year as the denominator.9 Rate estimates were not based on the population of overweight adults and were not adjusted for the number of adults who may have previously had a gastric bypass surgery.

Trends in annual bypass procedure rates were assessed with the χ2 test for trend.13 Overall differences for the period under study between female and male discharged patients, geographic region, and payer type were analyzed with the χ2 test and the Cochran–Mantel–Haenszel χ2 test. Non-parametric rank sum tests were used to test for trends or differences for patient age. Statistical significance was declared when the computed P value was less than .05. All statistical tests were 2-sided, and all analyses were performed with SAS for Windows software (SAS Institute Inc, Cary, NC).

Annual rates and selected characteristics of patients undergoing gastric bypass surgery are summarized in Table 1. The annual rate of gastric bypass surgeries increased significantly from 7.0 to 38.6 per 100 000 adults between 1998 and 2002 (P < .001). Overall, an estimated 180546 gastric bypass surgeries were performed; the estimated annual number of gastric bypass surgeries increased sharply from 14089 in 1998 to 82 636 in 2002. The Roux-en-Y procedure—the “gold standard” of bariatric surgical procedures—was the most commonly performed type of gastric bypass procedure, accounting for slightly more than 70% of the procedures performed annually.5,1416

Comorbidities accompanying gastric bypass surgery are summarized in Table 2. Overall, the most common comorbid conditions associated with the surgery were diabetes and chronic pulmonary disease.

Women received a consistently greater percentage of bypass surgeries annually (about 80%). Overall, the estimated total number of bypass surgeries performed on women (150 249 procedures) was nearly 5 times the number performed on men (30297 procedures).

In this nationally representative sample of adult patients undergoing gastric bypass surgery for the treatment of obesity, we observed a nearly 6-fold increase in surgery rates. Previous national and statewide population-based studies6,1719 reported similar findings. One plausible explanation for the marked increase in rates beginning in 2000 is the 2001 US Food and Drug Administration approval of the laparoscopic-adjustable gastric banding surgical technique.14,20 Although this surgery is more costly and time intensive, patient recovery times are shorter, and the surgery itself is less invasive.2124

Obesity is accompanied by a host of chronic and life-threatening comorbid conditions.14,2528 Thus, the maintained and significant weight loss resulting from gastric bypass surgery may prove, in the long term, to be cost-effective and health-preserving. Hence the observed upward trend in the number of gastric bypass surgeries is not surprising.

TABLE 1— Gastric Bypass Surgery in the United States, 1998–2002
TABLE 1— Gastric Bypass Surgery in the United States, 1998–2002
 19981999200020012002P for Trend
Payment source was private insurance, %64.656.373.674.878.0<.001
Total no.14 08913 96226 63643 22382 636 
No./100 0007.06.913.020.538.6<.001
Roux-en-Y-procedure, %76.472.580.580.076.4.39
Mean age (SD)
    Total sample40.0 (9.9)47.2 (9.7)39.6 (9.2)41.5 (10.4)41.3 (10.8)<.001
    Men43.6 (6.6)51.0 (10.3)41.2 (9.6)44.7 (11.6)42.9 (9.9)<.001
    Women39.2 (10.4)46.3 (9.3)39.3 (9.1)41.0 (10.1)40.0 (10.9)<.001
Female, %80.979.484.186.582.3<.001
Northeast, no./100 0004.510.811.221.037.2<.001
Midwest, no./100 0006.47.016.420.636.6<.001
South, no./100 0007.93.410.018.946.9<.001
West, no./100 0008.38.914.822.328.3<.001
TABLE 2— Summary of Comorbid Conditions (%) Accompanying Gastric Bypass Surgeries in the United States, 1998–2002
TABLE 2— Summary of Comorbid Conditions (%) Accompanying Gastric Bypass Surgeries in the United States, 1998–2002
 Overall (N= 180546)Female (n= 150249)Male (n= 30297)
Myocardial infarction0.10.12.3
Congestive heart failure1.51.61.1
Peripheral vascular disease0.00.00.0
Cerebrovascular disease0.00.00.0
Chronic pulmonary disease12.213.93.7
Connective tissue disease0.60.60.5
Ulcer disease0.30.20.9
Mild liver disease4.74.26.9
Moderate to severe renal disease0.70.23.5
Moderate to severe liver disease0.10.10.0
Metastatic solid tumor0.10.00.4

The authors acknowledge Elizabeth M. Smigielski of the University of Louisville Kornhauser Health Sciences Library for her expert assistance with the literature search process in support of this research.

Human Participant Protection No institutional review board approval was required for this study. This study involved only a secondary data analysis of data extracted from a public use database.


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Tonya M. Smoot, PhD, Ping Xu, MSPH, Peter Hilsenrath, PhD, Nancy C. Kuppersmith, MS, and Karan P. Singh, PhDTonya M. Smoot, Ping Xu, and Nancy C. Kuppersmith are with the University of Louisville, Louisville, Ky. Peter Hilsenrath and Karan P. Singh are with the University of North Texas Health Sciences Center, Fort Worth. “Gastric Bypass Surgery in the United States, 1998–2002”, American Journal of Public Health 96, no. 7 (July 1, 2006): pp. 1187-1189.


PMID: 16735625