A study of nearly one million patients
who underwent bariatric surgery found that both seasonality and
latitude were associated with health outcomes following surgery.
Bariatric surgery provides a weight
loss option for individuals with severe obesity who have been unable
to lose weight using other methods. The surgery causes weight loss
by limiting the amount of food the stomach can hold.
Side effects of bariatric surgery may
include infection, diarrhea, nutritional deficiencies, gallstones,
hernias and dehiscence. Dehiscence refers to a ruptured wound along
the surgical incision. These side effects may occur right after
surgery, causing a prolonged length of stay (LOS) in the hospital, or
the side effects may occur later.
As the obesity epidemic continues to
rise, bariatric surgery will likely become more common. Thus, it is
critical to optimize the results of these surgeries by managing
modifiable risk factors.
In a past study, researchers discovered
that 80% of patients who underwent gastric bypass were considered
vitamin D deficient a year after surgery, despite all patients
receiving vitamin D supplementation after surgery.
Vitamin D strengthens the immune system
by increasing the production of antimicrobial proteins, which aid in
fighting off infections and disease. Furthermore, research has found
low vitamin D status is associated with increased LOS and increased
incidence of hospital mortality. Because of these findings,
researchers recently became interested in the relationship between
vitamin D status and adverse outcomes following bariatric surgery.
In a recent study, researchers assessed
proxies of vitamin D status and outcomes after bariatric surgery of
932,091 patients. The researchers used both seasonality and latitude
to estimate vitamin D status. Those who live near the equator have
more opportunity to synthesize vitamin D from the sun, and therefore,
patients who attended hospitals located at or above 37° North were
considered to have lower vitamin D levels on average compared to
those located below 37° North.
In a separate analysis, the researchers
compared seasonality of the surgery to adverse health outcomes.
During the summer (July to September), vitamin D status is highest;
whereas, during the winter (January to March) vitamin D status is the
lowest. Vitamin D status is considered moderate during both fall and
spring.
The study presents promising findings
for the role of vitamin D in bariatric surgery. The large sample
size increased the strength of the findings. Furthermore, the
significant relationships between proxies of vitamin D status and
adverse outcomes of bariatric surgery remained after adjusting for
several confounding factors.
On the other hand, the study did not
directly measure vitamin D status. Instead, the researchers looked at
latitude and seasonality to represent vitamin D status. The vitamin D
status of the patients could be significantly higher than expected
based on latitude or season if they supplemented with vitamin D.
Lastly, due to the observational design, the study does not prove
that Northern latitude or surgery conducted during winter causes
adverse outcomes for bariatric surgery patients, but rather, these
proxies for low vitamin D status are linked to adverse outcomes.
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