Effect of body mass index on outcome after aneurysmal subarachnoid hemorrhage treated with clipping versus coiling

OBJECTIVE It has been suggested that increased body mass index (BMI) may confer a protective effect on patients who suffer from aneurysmal subarachnoid hemorrhage (aSAH). Whether the modality of aneurysm occlusion influences the effect of BMI on patient outcomes is not well understood. The authors aimed to compare the effect of BMI on outcomes for patients with aSAH treated with surgical clipping versus endovascular coiling. METHODS The authors retrospectively reviewed the outcomes for patients admitted to their institution for the management of aSAH treated with either clipping or coiling. BMI at the time of admission was recorded and used to assign patients to a group according to low or high BMI. Cutoff values for BMI were determined by classification and regression tree analysis. Predictors of poor functional outcome (defined as modified Rankin Scale score > 2 measured = 90 days after the ictus) and posttreatment cerebral hypodensities detected during admission were then determined separately for patients treated with clipping or coiling using stepwise multivariate logistic regression analysis. RESULTS Of the 469 patients admitted to the authors' institution with aSAH who met the study's inclusion criteria, 144 were treated with clipping and 325 were treated with coiling. In the clipping group, the frequency of poor functional outcome was higher in patients with BMI = 32.3 kg/m2 (47.6% vs 19.0%; p = 0.007). In contrast, in the coiling group, patients with BMI = 32.3 kg/m2 had a lower frequency of poor functional outcome at = 90 days (5.8% vs 30.9%; p < 0.001). On multivariate analysis, high BMI was independently associated with an increased (OR 3.92, 95% CI 1.20-13.41; p = 0.024) and decreased (OR 0.13, 95% CI 0.03-0.40; p < 0.001) likelihood of poor functional outcome for patients treated with clipping and coiling, respectively. For patients in the surgical group, BMI = 28.4 kg/m2 was independently associated with incidence of cerebral hypodensities during admission (OR 2.44, 95% CI 1.16-5.25; p = 0.018) on multivariate analysis. For patients treated with coiling, BMI = 33.2 kg/m2 was independently associated with reduced odds of hypodensities (OR 0.45, 95% CI 0.21-0.89; p = 0.021). CONCLUSIONS The results of this study suggest that BMI may differentially affect functional outcomes after aSAH, depending on treatment modality. These findings may aid in treatment selection for patients with aSAH.