Mortality of the Severely Obese: A Population Study

Abstract

Objective: This study aimed to analyze the Clinical Practice Research Datalink to identify the prognostic factors of all-cause mortality in the severely obese.

Background: Patients who are severely obese [body mass index (BMI) ≥35 kg/m] are at increased risk of all-cause mortality as a result of metabolic sequelae including hyperlipidemia, hypertension, and diabetes. Bariatric surgery has been shown to reduce the severity of the metabolic complications of obesity.

Method: A case-controlled analysis was carried out of patients with a BMI of 35 kg/m or more from the Clinical Practice Research Datalink, a UK database of primary care clinics. Clinicopathological characteristics at baseline diagnosis were extracted. Cases of all-cause mortality were identified as a clinical endpoint. A Cox proportional hazard model was used to calculate hazard ratios (HRs) for different patient factors. A P value less than 0.050 was defined as significant.

Results: A total of 187,061 records were identified for analysis. Median follow-up time was 98.0 months (range: 3.0-1095.0). A total of 8655(4.6%) were identified as having died during the study period. The median time from baseline obesity diagnosis until death was 137.0 months (range: 3.0-628.7). Multivariate analysis found bariatric surgery to be associated with reduced risk of all-cause mortality (HR: 0.487; P < 0.001). The following were associated with increased risk of death: male sex (HR: 1.805; P < 0.001), BMI of 60 or greater (HR: 2.541; P < 0.001), hypertension (HR: 2.108; P < 0.001), diabetes (HR: 2.766; P < 0.001), and hyperlipidemia (HR: 1.641; P < 0.001).

Conclusions: Factors such as high BMI, diabetes, hyperlipidemia, and hypertension at first diagnosis of severe obesity were each independently associated with an increased risk of death. Bariatric surgery was shown to be associated with reduced risk of all-cause mortality. Improving access to bariatric surgery and public health campaigns can improve the prognosis of severely obese patients.