Scoliosis patients with a low body mass index have poorer outcomes after surgery


Daniel Pérez-Prieto (Orthopedic Department, Hospital del Mar, Barcelona, Spain) and others report in the European Spine Journal that adolescent idiopathic scoliosis patients with a low body mass index (BMI) have poorer outcomes after corrective surgery—independent of the curve magnitude and the percentage of correction—than patients with a normal BMI. The authors write that this indicates that “great care” should be taken when recommending surgery to scoliosis patients with a low BMI.

Pérez-Prieto et al comment that several studies have found “some connection” between adolescent idiopathic scoliosis and anorexia nervosa (eg. both present with a low BMI and an alternation in the corporal composition). They add: “It has been hypothesised that adolescent idiopathic scoliosis might involve some disturbance in physical perception much the same as in anorexia nervosa and, therefore, it may influence adolescent idiopathic scoliosis surgery outcomes.” The aim of their study was to determine if the presence of a low BMI in patients with adolescent idiopathic scoliosis influenced surgical outcomes and satisfaction.

The authors, using data from two hospitals, reviewed outcomes for 35 females and four males who had undergone corrective surgery for adolescent idiopathic surgery. They extracted information on BMI, body composition, and preoperative Cobb angles from a previous study of the same group and measured the Cobb angle and calculated the percentage of correction three years after surgery.  Patients in the study were also asked to fill in the body shape questionnaire 14 (BSQ-14) and the Scoliosis Research Society questionnaire 22 (SRS-22).

The mean BMI was 19.17kg/m2 with 13 patients having a BMI of <18kg/m2—a person with a BMI of 18.5kg/m2 or less is considered to be underweight. The mean BSQ-14 score was 40.67 points and in this study, a patient with a score of 40 points or above was considered to have a “physical perception disturbance”.  In the group of patients with a BMI of <18kg/m2, the average BSQ-14 was 46.62 points compared with 37.69 points in the group of patients with a BMI of >18kg/m2 (p=0.057).

Pérez-Prieto et al report: “Results were worse in the group of slimmer patients in all SRS-22 subscales and all satisfaction questions. The group with a BMI of <18kg/m2 obtained a total of 82.31 points in the SRS-22 and it was 93.45 points for the group with a BMI of >18kg/m2 (p=0.001).” They add that significantly more patients in the <18kg/m2 group were dissatisfied with their back and shoulder shape after surgery than patients in the >18kg/m2 group—30.8% vs. 7.7% (p=0.001). However, no differences in terms of the Cobb correction (p=0.29) or the percentage of correction (p=0.8411) were found between groups.

The authors also found that patients with physical perception disturbance had significantly worse outcomes than those without this disturbance—SRS-22 total of 82.90 points vs. 96.10 points, respectively (p<0.001).

Concluding, Pérez-Prieto et al state: “Patients with a low BMI and a body perception disorder (and probably diagnosed with anorexia nervosa) obtain worse clinical outcomes after adolescent idiopathic corrective surgery.” They add that “great care” should be taken when recommending surgery to these patients and that “a referral for psychiatric evaluation may provide a formal contraindication for surgical scoliosis correction.”

Commenting, Pérez-Prieto told Spinal News International: “The results of the study showed that patients with a low BMI and/or a self-image perception disorder obtain poor outcomes after AIS corrective surgery and they are unsatisfied. This is very important for a spinal specialist because the outcome of the surgery can be influenced by non-orthopaedic pathology. Therefore it could be very helpful to work with psychiatrists and ask for their advice before surgery. The question that remains unclear is if those patients with a physical perception disturbance would obtain better results after psychiatric treatment.”