The scoliosis paradox: uncovering unexpected cardiovascular protection in a nationwide analysis of spinal curvature and MACE

Background The cardiovascular implications of spinal deformities remain incompletely elucidated, with most investigations focusing on congenital heart disease in individuals with scoliosis. The potential hemodynamic and mechanical consequences of age-related and acquired scoliosis on cardiac function in adults with normally developed hearts represent a significant knowledge gap. Recent data from the UK Biobank cohort (n=502,324) suggested an elevated lifetime risk of major adverse cardiovascular events (MACE) among individuals with scoliosis, predominantly attributable to heart failure and atrial fibrillation. Purpose This investigation aimed to rigorously evaluate scoliosis as an independent predictor of MACE and specific cardiovascular sequelae in a comprehensive, nationally representative United States inpatient cohort. Methods We conducted a retrospective cohort analysis utilizing the National Inpatient Sample (NIS) database, encompassing US hospitalizations from January 2017 through December 2019. Within this cohort, patients with documented lifetime history of scoliosis were identified. The primary endpoint comprised MACE, defined as a composite of acute myocardial infarction, heart failure, stroke, and cardiac arrest. Secondary endpoints included individual cardiovascular events. Multivariate logistic regression models were constructed with adjustment for age, gender, race, income quartile, Charlson comorbidity index, and covariates demonstrating p<0.2 in univariate screening. Results From an estimated population of 90,900,000 hospitalized patients, 618,240 (0.85%) had a documented history of scoliosis. The scoliosis cohort demonstrated a female predominance (73% vs 57% in general population) and slightly advanced age (60 vs 58 years). Following comprehensive multivariate adjustment, scoliosis was associated with significantly reduced odds of MACE (adjusted OR 0.83, 95% CI 0.81-0.84, p<0.001). All secondary cardiovascular endpoints demonstrated reduced risk: acute myocardial infarction (adjusted OR 0.63, 95% CI 0.60-0.66, p<0.001), stroke (adjusted OR 0.62, 95% CI 0.58-0.65, p<0.001), atrial fibrillation (adjusted OR 0.81, 95% CI 0.79-0.83, p<0.001), arrhythmia (adjusted OR 0.84, 95% CI 0.82-0.85, p<0.001), and heart failure (adjusted OR 0.92, 95% CI 0.90-0.94, p<0.001). Conclusion In contrast to previously published data, our nationwide analysis demonstrates that scoliosis is independently associated with reduced risk of MACE and improved cardiovascular outcomes in a large US inpatient population. This unexpected cardioprotective association warrants further investigation through prospective studies stratified by scoliosis etiology, severity, therapeutic intervention, and age of onset to elucidate potential underlying mechanisms and inform clinical management algorithms for this patient population.