Bone Abstracts

Background: Scoliosis is lateral curvature of the spine ≥10°, as measured on standing spinal radiographs. There are no published studies that have investigated determinants of scoliosis using a prospective cohort design, making the establishment of cause and effect difficult. Several large population-based cohorts exist throughout the world with a wide range of data already collected, and while spinal imaging with radiographs is not generally collected in these cohorts, DXA has been routinely performed at repeated time points for the study of determinants of bone density. We therefore wished to develop and validate a novel method of identifying scoliosis on total body DXA scans.

Methods: Scoliosis was identified on total body DXA scans by triaging to distinguish true curves from positioning errors, followed by a modified-Ferguson method to measure angles. Precision was assessed on 174 children from the Avon Longitudinal Study of Parents and Children (ALSPAC), who underwent repeat DXA scans at age 15, 2–6 weeks apart. In addition, precision of angle estimation was evaluated on 20 scans measured five times. To evaluate accuracy, angle size was compared to spinal radiographs in 13 individuals with known scoliosis. Scoliosis prevalence rates and curve patterns were then identified from DXA scans previously obtained in 5122 ALSPAC participants at aged 15.

Results: There was substantial agreement in identifying those with scoliosis on repeat DXA scans taken 2–6 weeks apart (Kappa of 0.74, 95% CI 0.59 to 0.89). 95% of repeat angle measures were within 5°. Prevalence of scoliosis ≥10° in ALSPAC was 3.5% at aged 15, and was higher in girls. Mean±S.D. curve size was 15±7° at aged 15.

Conclusions: We have developed and validated a novel method for identifying scoliosis from DXA scans. Comparison with prevalence data using more established techniques suggests our method provides valid estimates of scoliosis prevalence in population-based cohorts.