Two Studies Show that
Obesity Surgery Does Improve Mortality
Outcomes
by David W. Sharp
Medicine Top Ten
Papers
Rank
Papers
Cites Jan-Feb
09
Rank
Nov-Dec 08
1
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There is as yet no established clinical specialty
of bariatrics, but if worldwide obesity trends continue
one may soon be needed. However, we do have
bariatric surgery, which covers
several different operative procedures on the
stomach such as gastric banding. Surgery is usually
a last resort and guidelines suggest that only
exceptionally should it be resorted to if the
patient’s body-mass index (or BMI, determined
by weight in kilograms divided by the square of
height in meters) is below 40. Obesity is defined by
a BMI of 30 or more.
When the Swedish Obese Subjects (SOS) controlled but
non-randomized follow-up study began in 1987 it would
not have been certain that weight-reducing surgery
would benefit mortality. The position would have been a
little clearer by the time recruitment ended in early
2001. Even so, the central message of the main SOS
paper, which was at #14 last time and has now inched up
to #13 (L. Sjostrom, et al., New Engl. J.
Med., 357[8]: 741-52, 23 August 2007; total cites
163, latest count 38) is important. Bariatric surgery
for severe obesity was associated both with long-term
weight loss and with reduced mortality. The surgery
group numbered 2,010 and the matched controls (given
non-standardized conventional treatments) 2,037.
After an average follow-up of almost 11 years, 6.3% of
the controls had died
compared with 5.0% of the
surgery group. There were very few early
postoperative deaths (five within 90 days of
surgery). The controls experienced no meaningful
weight change but at 10 years the surgical
patients had average losses of 14-25%, depending
on the type of operation.
Science Watch asked Dr. Lars Sjostrom what
influence this 2007 paper might have had on patient
choices in Sweden and elsewhere. Sweden has a
population of only 9 million, and in 2002 about 700
bariatric operations were done, says Dr. Sjostrom. At
that time the figure for the USA would have been more
than 100,000. In 2008 the Swedish figure had quadrupled
to 2,800. Sjostrom reckons that referrals for such
surgery have doubled in the past two or three years but
does not know if this change reflects "increased
pressure from obese patients or an increased interest
from referring doctors."
Today’s BMI-above-40 criterion was not in place
back in 1987, and in SOS the cutoffs were 34 for men
and 38 for women. How important is this difference,
Science Watch wondered? Not at all, it seems.
The relative effect of surgery on mortality was no
different for patients above and below the median BMI
in these patients, which was 40.8. In Sjostrom’s
opinion, "most obese patients with BMI 35 to 40
kg/m2 will not obtain efficient lifelong
treatment without bariatric surgery, given the current
non-surgical treatment modalities available."
Those in the 35 to 40 BMI range have a poor
health-related quality of life; in patients who are
operated on, quality of life improves, and the greater
the weight loss the more the improvement (J. Karlsson,
et al., Int. J. Obesity, 31[ 8]: 1248-61,
2007). Finally, Science Watch touched on
advances in surgical technique since 1987-2001, the
years of recruitment to SOS, an example being
laparoscopic ("keyhole") surgery. "Probably, we
obtained the favorable results not due to but in spite
of old-fashioned methodology," says Sjostrom. With
today’s methods, the advantages of bariatric
surgery might have been even greater.
Accompanying the SOS paper at #13 came data from a
retrospective study of mortality in surgery patients
and matched controls (T. D. Adams, et al.,
New Engl. J. Med., 357[8]: 753-61, 23 August
2007; 19 citations for this period, 108 overall)
supporting the conclusions of Dr. Sjostrom and his
colleagues. In this study, 7,925 patients undergoing
gastric bypass surgery were compared with a matched
number of obese patients applying for driving licenses.
After about seven years of follow-up, the mortality
rate was lower in the surgical group (37.6 versus 57.1
deaths per 10,000 patient-years). A tendency for
non-disease-related deaths to be higher in the surgery
group does not appear in the SOS study. Again, quality
of life improved with surgery (R.L. Kolotkin, et
al., Surg. Obes. Related Dis., 5[2]:
250-6, March 2009).
A former deputy editor of The Lancet,
Mr. David W. Sharp, M.A. (Cambridge), is a freelance
writer living in Minchinhampton, U.K.
KEYWORDS: BARIATRIC SURGERY, WEIGHT-LOSS SURGERY,
ANTI-OBESITY SURGERY, GASTRIC BYPASS, SWEDISH OBESE
SUBJECTS, SOS STUDY, LARS SJOSTROM, BARIATRIC SURGERY
AND MORTALITY, ROUX-EN-Y, QUALITY OF LIFE, BMI.