Association of bariatric surgery with risk of acute care use for hypertension-related disease in obese adults: population-based self-controlled case series study

Yuichi J. Shimada, Yusuke Tsugawa, Hiroyasu Iso, David F. M. Brown, Kohei Hasegawa

Hypertension carries a large societal burden. Obesity is known as a risk factor for hypertension. However, 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). We 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. We 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 hospitalization in three states (California, Florida, and Nebraska) from 2005 to 2011. The primary outcome was acute care use for hypertension-related disease. We 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. We identified 980 obese patients with hypertension who underwent bariatric surgery. The median age was 48 years (interquartile range, 40-56 years), 74% were female, and 55% were non-Hispanic white. During the reference period, 17.8% (95% confidence interval [CI], 15.4-20.2%) had a primary outcome event. The risk remained unchanged in the subsequent 12-month pre-surgery period (18.2% [95% CI, 15.7-20.6%]; adjusted odds ratio [aOR] 1.02 [95% CI, 0.83-1.27]; P = 0.83). In the first 12-month period after bariatric surgery, the risk significantly decreased (10.5% [8.6-12.4%]; aOR 0.58 [95% CI, 0.45-0.74]; P < 0.0001). Similarly, the risk remained significantly reduced in the 13-24 months after bariatric surgery (12.9% [95% CI, 10.8-15.0%]; aOR 0.71 [95% CI, 0.57-0.90]; P = 0.005). By contrast, there was no significant reduction in the risk among obese patients who underwent non-bariatric surgery (i.e., cholecystectomy, hysterectomy, spinal fusion, or mastectomy). In this population-based study of obese adults with hypertension, we found that the risk of acute care use for hypertension-related disease decreased by 40% after bariatric surgery. The data provide the best evidence on the effectiveness of substantial weight loss on hypertension-related morbidities, underscoring the importance of discussing options for weight reduction when treating obese patients with hypertension.