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Hypertension-related morbidities

Substantial weight loss reduces hypertension-related morbidities

The researchers used conditional logistic regression to compare each patient's risk of the outcome event during sequential 12-month periods, using pre-surgery months 13–24 as the reference period
The type of bariatric surgery showed that the point estimate of the odds ratio was lower after gastric bypass compared to gastric banding

Patients who have substantial weight loss after bariatric surgery reduce their risk of acute care use for hypertension-related disease decreased by 40%, according to research by investigators from Osaka University Graduate School of Medicine Department of Emergency Medicine, Massachusetts General Hospital and Harvard Medical School. The paper, ‘Association of bariatric surgery with risk of acute care use for hypertension-related disease in obese adults: population-based self-controlled case series study’, was published in BMC Medicine.

Although obesity is known as a risk factor for hypertension, little is known as to whether weight loss interventions reduce the risk of hypertension-related adverse events, such as acute care use (emergency department [ED] visit and/or unplanned hospitalization). Therefore, the researchers used bariatric surgery as an instrument for investigating the effect of large weight reduction on the risk of acute care use for hypertension-related disease in obese adults with hypertension.

In their study, they performed a self-controlled case series study of obese patients with hypertension who underwent bariatric surgery using population-based ED and inpatient databases that recorded every bariatric surgery, ED visit, and hospitalisation in three states (California, Florida, and Nebraska) from 2005 to 2011. The primary outcome was acute care use for hypertension-related disease. The researchers used conditional logistic regression to compare each patient's risk of the outcome event during sequential 12-month periods, using pre-surgery months 13–24 as the reference period.

To delineate the differential effects of individual types of bariatric surgery on the risk of acute care use for HTN-related disease, they performed separate self-controlled case series analyses for gastric bypass and gastric banding.

Outcomes

In total, 980 patients were included in the primary analysis, the median age was 48 years, 74% were female and 55% were non-Hispanic white. During the reference period (13–24 months prior to bariatric surgery), they observed at least one acute care use for HTN-related disease in 17.8% (95% CI 15.4–20.2%) of the study population. The risk did not change in the following 12-month pre-surgery period (18.2%, 95% CI 15.7–20.6%), corresponding to an aOR of 1.02 (95% CI 0.83–1.27; p=0.83).

In contrast, they observed a significant decline in the risk after bariatric surgery. Within 12 months after bariatric surgery, 10.5% (95% CI 8.6–12.4%) experienced an acute care use for HTN-related disease (aOR 0.58, 95% CI 0.45–0.74; p<0.0001). The risk remained significantly reduced during the subsequent period of 13–24 months post-surgery (12.9%, 95% CI 10.8–15.0%), corresponding to an aOR of 0.71 (95% CI 0.57–0.90; p=0.005).

In the stratification analysis by age group with a limited statistical power, a similar risk reduction was observed in the 18–44 and 45–54 year age groups. The sensitivity analysis stratified by sex showed that women had a similar reduction in the risk over the 2-year post-surgery period, while men had a significant reduction only in the first 12 months after bariatric surgery. The sensitivity analysis according to the type of bariatric surgery showed that the point estimate of the odds ratio was lower after gastric bypass compared to gastric banding.

By using population-based data of patients with HTN who underwent bariatric surgery in the three diverse states, the researchers report that the risk of acute care use for HTN-related disease decreased by 40% after bariatric surgery. The observed large decline in the risk remained significant for at least two years after surgery. However, other non-bariatric surgeries were not associated with a reduced risk of acute care use for HTN-related disease, addressing the possibility that the observed decrease in the risk might be attributable to intensified blood pressure control during the peri-surgical period.

Our data, along with prior evidence, collectively indicate that substantial weight loss may reverse the link between obesity and HTN-related morbidities.

“This self-controlled case series study using large population-based datasets from three US states demonstrated that bariatric surgery is associated with a significant reduction in the risk of acute care use for hypertension -related disease among obese adults with hypertension,” the authors conclude. “However, a large proportion of obese adults with hypertension would choose not to undergo bariatric surgery for various reasons, such as an absence of indications, lack of insurance coverage, and peri-surgical risk. Our data also underscore the importance of developing safe and effective non-invasive weight loss strategies for obese patients with Hypertension to relieve the large societal burden of acute care use for hypertension -related disease. Such effort should progress in concert with public health interventions to primarily prevent obesity and hypertension to begin with.”

To access this paper, please click here

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