Prevalence and impact of low body mass index on outcomes in patients with adolescent idiopathic scoliosis: a systematic review.

Comparatively lower body mass index (BMI) has been reported in patients with adolescent idiopathic scoliosis (AIS)-a feature which may be an unrecognised symptom, or an organic consequence of the condition. The primary aim of this systematic review is to investigate the relationship between low BMI and AIS. A secondary aim is to investigate the effect of low BMI on outcomes of postsurgical correction in this patient group. The Cochrane Library, PubMed, SCOPUS, Web of Science and Ovid MEDLINE databases were searched up to December 2016 for relevant studies that reported prevalence of low preoperative BMI in patients with AIS and/or compared BMI between patients with AIS and healthy controls, as well as those that examined the relationship between low BMI and postoperative outcomes. Forty-five eligible studies were identified from the search strategy. Mean differences (MDs) were used with 95% confidence intervals (CI) in a random effects model to compare BMI in patients with AIS and controls in a pooled analysis of data from nine eligible studies (n = 3747 patients). In the meta-analysis, BMI of patients in the AIS group was significantly lower than those in the control group (MD -1.19, 95% CI -1.78 to -0.60). Low BMI in AIS can impact postoperative outcomes, including increased risk of ileus. This review demonstrates that patients with AIS are significantly more likely to have a low BMI compared to the general population. We advocate that closer attention be paid to AIS patients with low BMI both pre- and postsurgical correction.