Study design: A controlled prospective cross-sectional case study.
Objective: To investigate body mass index (BMI) and corporal composition in girls with adolescent idiopathic scoliosis (AIS) and compare them with a normal population matched by sex and age. There is controversy as to whether there are real anthropometric alterations in patients with AIS. Relative to the weight or the BMI, some studies find differences and other studies do not detect them. AIS and anorexia nervosa (AN) make their debut during adolescence and both may be associated with an alteration of their subjective physical perception. Some authors propose a link between AIS and AN supported both by an alteration of physical perception and lower BMI. No studies on body composition in AIS have been published.
Methods: Adolescent idiopathic scoliosis patient surgery candidates during 2008 were studied. Body composition was evaluated using the bioelectrical impedance analysis (Bodystat, Isle of Man, UK). A study population of more than 5,000 patients that was published by Kyle et al. (Nutrition 17:534-541, 2001) was chosen as a control (group 1). Another control group (group 2) of healthy volunteers matched by sex and age was selected among a school age and university population in Barcelona, Spain. A variance analysis was used to analyze differences between the mean values of the control group 1, the European control group, and the AIS patient surgery candidates (Epiinfo 6.2001). Comparisons between the AIS patients and control group 2 were performed with the T Student test of unpaired samples using the SPSS 15.0 (Statistical Package Social Science) software.
Results: Twenty-seven women with a mean age of 17.4 years. BMI was 18.9 kg/m(2) (SD 1.7; 95 % CI 18.31-19.73). In the variance analysis, a significant difference between AIS and group 1 in BMI was observed (21.0 vs. 18.9, p = 0.000004); fat-free mass (FFM = 42.6 vs. 38.9, p = 0.0000009) and fat mass (FM = 15.6 vs. 13.7, p = 0.03). Significant differences in BMI (22.13 vs. 18.9, p = 0.001; 95 % CI difference 1.85-4.60), fat mass index (FMi = 7.17 vs. 4.97, p = 0.000; 95 % CI difference 1.36-3.05) and fat-free mass index (FFMi = 14.95 vs. 13.09, p = 0.001; 95 % CI difference 0.26-1.86) between AIS and group 2 were also seen.
Conclusion: The conclusion is that there is a real alteration of body composition in AIS. The BMI, FFMi and FMi are lower than in the general population in the series under study.