Adolescent idiopathic scoliosis: risk factors for complications and the effect of hospital volume on outcomes

Abstract

OBJECTIVE Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis. Limited literature exists defining risk factors associated with outcomes during initial hospitalization in these patients. In this study, the authors investigated patient demographics, clinical and hospital characteristics impacting short-term outcomes, and costs in adolescent patients undergoing surgical deformity correction for idiopathic scoliosis. Additionally, the authors elucidate the impact of hospital surgical volume on outcomes for these patients. METHODS Using the National Inpatient Sample database and appropriate International Classification of Diseases, 9th Revision codes, the authors identified adolescent patients (10-19 years of age) undergoing surgical deformity correction for idiopathic scoliosis during 2001-2014. For national estimates, appropriate weights provided by the Agency of Healthcare Research and Quality were used. Multivariable regression techniques were employed to assess the association of risk factors with discharge disposition, postsurgical neurological complications, length of hospital stay, and hospitalization costs. RESULTS Overall, 75,106 adolescent patients underwent surgical deformity correction. The rates of postsurgical complications were estimated at 0.9% for neurological issues, 2.8% for respiratory complications, 0.8% for cardiac complications, 0.4% for infections, 2.7% for gastrointestinal complications, 0.1% for venous thromboembolic events, and 0.1% for acute renal failure. Overall, patients stayed at the hospital for an average of 5.72 days (median 5 days) and on average incurred hospitalization costs estimated at $54,997 (median $47,909). As compared with patients at low-volume centers (≤ 50 operations/year), those undergoing surgical deformity correction at high-volume centers (> 50/year) had a significantly lower likelihood of an unfavorable discharge (discharge to rehabilitation) (OR 1.16, 95% CI 1.03-1.30, p = 0.016) and incurred lower costs (mean $33,462 vs $56,436, p < 0.001) but had a longer duration of stay (mean 6 vs 5.65 days, p = 0.002). In terms of neurological complications, no significant differences in the odds ratios were noted between high- and low-volume centers (OR 1.23, 95% CI 0.97-1.55, p = 0.091). CONCLUSIONS This study provides insight into the clinical characteristics of AIS patients and their postoperative outcomes following deformity correction as they relate to hospital volume. It provides information regarding independent risk factors for unfavorable discharge and neurological complications following surgery for AIS. The proposed estimates could be used as an adjunct to clinical judgment in presurgical planning, risk stratification, and cost containment.

Keywords: AHRQ = Agency for Healthcare Research and Quality; AIS = adolescent idiopathic scoliosis; CCI = Charlson Comorbidity Index; GEE = generalized estimating equation; HCUP = Healthcare Cost Utilization Project; HVC = high-volume center; ICD-9-CM = International Classification of Diseases, 9th Revision, Clinical Modification; LOS = length of hospital stay; LVC = low-volume center; NIS; NIS = National Inpatient Sample; NPR = number of inpatient procedures; OLS = ordinary least squares; SRS = Scoliosis Research Society; adolescent idiopathic scoliosis; complications; cost; hospital volume; outcomes.