Score distribution of the scoliosis quality of life index questionnaire in different subgroups of patients with adolescent idiopathic scoliosis

Prospective cross-sectional measurement study. To analyze the score distribution on the Scoliosis Quality of Life Index (SQLI) questionnaire domains and items for subjects with adolescent idiopathic scoliosis (AIS). The SQLI was derived from the SRS-22 questionnaire so that it would be more applicable to persons with AIS between 10 and 18 years old. However, the score distribution of the SRS-22 is characterized by high ceiling effects within subgroups of persons with AIS. The SQLI questionnaire was completed by 95 females with AIS. Floor, ceiling effects, and score distribution were examined for subgroups based on age (n = 4), management (4), curve severity (3), and curve type (6). Ceiling effect proportions (0%-40%) were higher than floor effects (n = 1). Back pain and satisfaction were the only domains with ceiling effects exceeding 20%. For some domains, ceiling effects were significantly most prevalent for younger subgroups, those with low or moderate curve severity and those treated less aggressively. High ceiling effects were also observed for the observation, postsurgical, main thoracic, and double major curves subgroups. More than half the participants scored over 4/5 for all SQLI domains in the overall sample and in the observation, surgery,