The impact of BMI on mechanical thrombectomy outcomes, insights from a comprehensive stroke center

Identifying predictors of outcomes following mechanical thrombectomy (MT) for stroke is crucial for selecting patients most likely to benefit from the treatment as well as guiding prognostication efforts. When it comes to the role of Body Mass Index (BMI) as a prognostic marker in that context, the evidence is conflicting. A retrospective analysis of a prospectively maintained database including patients undergoing MT between the 2016 and 2024 was performed. The main outcomes were functional recovery (discharge modified Rankin Scale (mRS); < 3 vs. ≥3), discharge National Institute of Health Stroke Scale (NIHSS) score, and in-hospital mortality. Multivariable regression and propensity score matching (PSM) were used. A total of 894 patients were included: 16 (1.8%) underweight, 298 (33%) normal weight, 291 (33%) overweight, and 289 (32%) obese (18% class 1, 8.8% class 2, and 4.9% class 3 obesity). On adjusted multivariable regression analyses, none of the BMI categories were associated with discharge mRS (p ≥ 0.05). However, underweight status was an independent positive predictor of both discharge NIHSS score (β = 8.5, 95% CI 3.5-14, p = 0.001), and in-hospital mortality (OR = 6.27, 95% CI 0.95-34.4, p = 0.040). No associations between either discharge NIHSS score or mortality and other BMI categories could be found (p ≥ 0.05). After PSM, no differences in terms of technical difficulty, including number of thrombectomy attempts, length of procedure, and reperfusion success, could be established on the basis of BMI (p ≥ 0.05). While obesity was associated with comparable outcomes compared to normal BMI, underweight status was shown to independently worsen outcomes following MT for stroke. Further studies are needed to establish the nature of this association.