July 2006, Vol 96, No. 7 | American Journal of Public Health Smoot et al. | Peer Reviewed | Research and Practice | 1187
RESEARCH AND PRACTICE
TABLE 1—Gastric Bypass Surgery in the United States, 1998–2002
1998 1999 20002001 2002
P for Trend
Payment source was private
64.656.3 73.674.878.0 <.001
Mean age (SD)
Gastric Bypass Surgery
in the United States,
| Tonya M. Smoot, PhD, Ping Xu, MSPH,
Peter Hilsenrath, PhD, Nancy C. Kuppersmith,
MS, and Karan P . Singh, PhD
We assessed the prevalence of
gastric bypass surgeries in the United
States on the basis of data from the
1998 to 2002 National Hospital Dis-
charge Survey. Between 1998 and
2002, rates (per 100000 adults) in-
creased 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 pa-
tient outcomes, and increased pop-
ularity of this procedure. (Am J Pub-
lic Health. 2006;96:1187–1189. doi:10.
The prevalence of obesity in the US popu-
lation continues to increase, making obesity
a major public health concern.1–4Bariatric
surgery has become a popular method of
treating obesity, with gastric bypass surgery
emerging as the most widely used of these
We used the National Hospital Discharge
Survey, an annual probability sample of dis-
charged 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 by-
pass procedure from 1998 to 2002. A de-
tailed description of the sample design and
data collection method of the National Hospi-
tal Discharge Survey has been published in
Diagnoses and procedures in the National
Hospital Discharge Survey were coded ac-
cording to the International Classification of
Diseases, Ninth Revision, Clinical Modification
(ICD-9-CM).10Gastric 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 pa-
tients were identified by the presence of ac-
companying 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 inde-
pendent predictors in the Charlson Comorbid-
ity Index were used to measure the burden of
comorbid disease in our sample. The specific
diagnoses summarized are those for myocar-
dial infarction, congestive heart failure, pe-
ripheral vascular disease, dementia, cerebro-
vascular 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.1 1,12
The estimated annual number of gastric
bypass procedures was derived from the sam-
pling weights provided with the National
Hospital Discharge Survey. Annual popula-
tion rates were calculated by using the ad-
justed adult (aged 18 years or older) civilian
population of the United States in each corre-
sponding survey year as the denominator.9
Rate estimates were not based on the popula-
tion of overweight adults and were not ad-
justed for the number of adults who may
have previously had a gastric bypass surgery.
Trends in annual bypass procedure rates
were assessed with the χ2test 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 χ2test and the
Cochran–Mantel–Haenszel χ2test. Non-
parametric rank sum tests were used to test
for trends or differences for patient age. Sta-
tistical significance was declared when the
computed P value was less than .05. All sta-
tistical tests were 2-sided, and all analyses
were performed with SAS for Windows soft-
ware (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 signifi-
cantly from 7.0 to 38.6 per 100000 adults
between 1998 and 2002 (P<.001). Overall,
an estimated 180546 gastric bypass surger-
ies were performed; the estimated annual
American Journal of Public Health | July 2006, Vol 96, No. 71188 | Research and Practice | Peer Reviewed | Smoot et al.
RESEARCH AND PRACTICE
TABLE 2—Summary of Comorbid
Conditions (%) Accompanying Gastric
Bypass Surgeries in the United States,
Mild liver disease
Moderate to severe
Moderate to severe
0.6 0.6 0.5
number of gastric bypass surgeries increased
sharply from 14089 in 1998 to 82636 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.5,1 4–16
Comorbidities accompanying gastric bypass
surgery are summarized in Table 2. Overall,
the most common comorbid conditions asso-
ciated 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 (150249 procedures) was nearly 5
times the number performed on men
In this nationally representative sample of
adult patients undergoing gastric bypass sur-
gery for the treatment of obesity, we observed
a nearly 6-fold increase in surgery rates. Previ-
ous national and statewide population-based
studies6,1 7–19reported 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 surgi-
cal technique.1 4,20Although this surgery is
more costly and time intensive, patient recov-
ery times are shorter, and the surgery itself is
Obesity is accompanied by a host of
chronic and life-threatening comorbid condi-
tions.1–4,25–28Thus, the maintained and signif-
icant 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.
About the Authors
Tonya 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.
Requests for reprints should be sent to Tonya M. Smoot,
PhD, PO Box 548, Mansfield, TX 76063 (e-mail:
This brief was accepted September 2, 2005.
T.M. Smoot originated the study and was responsible
for statistical and methodological guidance, interpreta-
tion of data, and preparation of the brief. P. Xu con-
ducted all statistical analyses, summarized results, inter-
preted data, and was responsible for initial preparation
of the brief. All of the authors contributed to the writ-
ing, reviewing, and editing of the brief.
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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