Treatment pathways and outcomes in patients with BMI≥50 kg/m²: conservative treatment, immediate surgery or stepwise surgical approach

Introduction: In the developed world, obesity is one of the greatest public health problems. The global prevalence of obesity has increased substantially over the past 40 years. Obesity is associated with an increased risk for type 2 diabetes, hypertension, dyslipidaemia, cardiovascular diseases, certain types of cancer and mortality. Treatment options for obesity include non-surgical treatment and bariatric surgery.

Purpose: Bariatric surgery is the most effective treatment for patients with a BMI≥50 kg/m², yet preoperative conservative therapy is often mandated. The benefit of such an approach remains controversial. This study aimed to compare outcomes of conservative treatment alone, immediate surgery, and stepwise surgery following failed conservative therapy in patients with BMI≥50 kg/m².

Methods: All patients with BMI≥50 kg/m² presenting to a German bariatric center between 2015–2021 were retrospectively categorized into three groups: Non-Surg (conservative therapy only), Surg-First (immediate surgery), and Step-Treat (initial conservative therapy followed by surgery). Primary outcomes were assessed at 6, 12, and 24 months and included weight loss, resolution of obesity-associated comorbidities (hypertension, T2DM , dyslipidemia, OSAS), and overall outcome measured by the SF-BARI score.

Results: Of 918 screened patients, 538 met inclusion criteria and were allocated to Non-Surg (n=203), Surg-First (n=225), and Step-Treat (n=110) ([Fig. 1]). After 6 months, median%TWL and%EWL were significantly higher in the Surg-First group (%TWL: 23.6% vs. 0%;%EWL: 42% vs. 0%; both P<.001) compared to Non-Surg (Tab. 1). Only 3% of Non-Surg patients achieved adequate weight loss. Surg-First patients also showed higher remission rates of T2DM (54.1% vs. 21.2%; P<.001) and fewer de novo T2DM cases. Compared to Surg-First, the Step-Treat group showed comparable short-term weight loss, but significantly lower%TWL and%EWL at 12 and 24 months ([Fig. 2] & [3]). Severe postoperative complications (Grade IIIb) were more common in Step-Treat (11.8% vs. 3.6%; P<.001), and SF-BARI scores were significantly higher in Surg-First, indicating superior overall outcomes (Tab. 2).

Fig. 1  

Fig. 2  

Fig. 3  

Conclusion: In patients with BMI≥50 kg/m², immediate bariatric surgery was associated with superior weight loss, improved comorbidity resolution, and fewer complications compared to conservative therapy alone or a stepwise approach. These findings support direct surgical treatment in this population.

Publication History

Article published online:
04 September 2025