Clinical effectiveness of school screening for adolescent idiopathic scoliosis: a large population-based retrospective cohort study.

STUDY DESIGN Retrospective cohort study. OBJECTIVE To evaluate the clinical effectiveness of school scoliosis screening using a large and long-term-followed cohort of students in Hong Kong. SUMMARY OF BACKGROUND DATA School screening for adolescent idiopathic scoliosis has been criticized as resulting in over-referrals for radiography and having low predictive values. Indeed, all but one previous retrospective cohort studies had no follow-up assessments of students until their skeletal maturity, leaving any late-developed curves undetected. The one study that completed this follow-up was well conducted but had low precisions due to its small sample size. METHODS A total of 157,444 students were eligible for a biennial scoliosis screening, and their screening results and medical records up to 19 years of age were available. Students first had forward bending test and angle of trunk rotation (ATR) performed. Those with ATR between 5 degrees and 14 degrees or signs of adolescent idiopathic scoliosis were assessed by moiré topography regularly. Students with an ATR >or=15 degrees , >or=2 moiré lines, or significant clinical signs were referred for radiography and had their Cobb angle measured. RESULTS Of the 115,190 screened students in the cohort, 3228 (2.8%, 95% confidence interval [CI] = 2.7%-2.9%) were referred for radiography. At the final follow-up, the positive predictive values were 43.6% (41.8%-45.3%) for a Cobb angle >or=20 degrees and 9.4% (8.4%-10.5%) for needing treatment, while the sensitivities were 88.1% (86.4%-89.6%) and 80.0% (75.6%-83.9%), respectively. CONCLUSION This is the largest study that has demonstrated that school scoliosis screening in Hong Kong is predictive and sensitive with a low referral rate. Screening should thus be continued in order to facilitate early administration of conservative treatments.