WHAT IS THE DIAGNOSTIC ACCURACY OF COMMUNITY SPINE RADIOGRAPHS FOR ADOLESCENT IDIOPATHIC SCOLIOSIS BRACE CANDIDATES?

Timely diagnosis of Adolescent Idiopathic Scoliosis (AIS) allows for effective management through brace treatment, potentially preventing complex spine surgery. Concerningly, over 25% of patients are late referrals, increasing the rate of surgeries and associated complications that may be avoided with conservative management. Most AIS detection occurs in the community; however, community spine x-rays can be of inadequate quality and inaccurately interpreted. The study objective is to establish the diagnostic accuracy of community spine x-rays for AIS brace candidates. A review of AIS patients seen for initial visit at a tertiary care pediatric hospital between January-September 2021 was conducted, excluding those seen for second opinion, missing index Cobb angle or with index imaging from the same institution (n=170). The index test was the community spine x-ray obtained prior to referral and evaluated by community radiologist. Positive test to detect a brace candidate was dichotomized by Cobb angle (25-40 degrees) as per Scoliosis Research Society. Risser stage was not included in diagnostic criteria given significant missing data in index reports (n=110). Measures of diagnostic accuracy for the index test were determined against the reference standard if images were obtained within 90 days of the reference standard (n=111). The reference standard was the three-foot standing EOS spine x-ray obtained on initial visit and evaluated by orthopedic spine specialists. Sensitivity analyses were conducted on a subsample of data with index test within 60 days of the reference standard (n=67). Late referrals were defined as those who present as likely surgical candidates based on initial orthopedic evaluation. The study cohort was mostly female (76.6%) with an average age of 13.7 years (SD=1.6). The accuracy of the community spine x-ray to detect a brace candidate was 65.8% (95% CI 56.2-74.5). The sensitivity of the index test was 65.4% with a false negative rate of 34.6%. The specificity was 66.1% with a false positive rate of 33.9%. Positive and negative predictive values were 63.0% and 68.4%, respectively. The positive likelihood ratio was 1.99. Out of the total cohort (n=111), there were 38 misdiagnoses, 34 of which were due to underestimation. Of the total number of true brace candidates (n=52), 32.7% were missed because of underestimation (95% CI 21.5-46.2). With index images within 60 days of the reference standard, the accuracy remained 67.2% (95% CI 54.6-78.1). The proportion of missed brace candidates because of underestimation was unchanged when looking at 60-day data (p=0.37). The proportion of late referrals was 34.2%. Inaccuracies in community spine radiology may lead to missed opportunities for conservative treatment. This may be a contributing factor to referral trends thereby increasing rates of avoidable surgeries and costs to the health care system.