Objective : The QUO VADIS study evaluated disease activity and health-related quality-of-life (HRQoL) in ankylosing spondylitis (AS) patients treated with golimumab (GLM) or infliximab (IFX, originator) during routine clinical care. Methods : 'This prospective observational study followed biologics-naive AS patients newly treated with GLM or IFX for 6 months. Disease activity (BASDAI, BASFI, ASAS, and ASDAS) and HRQoL improvement (>= 5 points of SF-36 Physical Component Summary [PCS] score; PCS response) were measured. A Classification and Regression Trees (CART) analysis evaluated association of baseline parameters with PCS response at 6 months. Results : 963 patients (mean age 43 years, 61% male, 64% HLA-B27 positive) received >= 1 dose of medication (78% GLM; 22% IFX). Disease activity was reduced; mean (SD) changes from baseline at month 6 of -2.7 (BASDAI) and -2.1 (BASFI) and 40% and 35% achievement of BASDAI50 and ASAS40 response, respectively, were observed. PCS response was achieved at month 6 in 52% of patients. Using CART analysis, baseline parameters (cut-off values) associated with HRQoL improvement were ASDAS (>= 3.48), C-reactive protein (>= 8.55 mg/L), age (>= 35.5 years), and BASFI (>= 1.15). This algorithm correctly identified 57.5% (sensitivity) of PCS responders (>= 5 points) and 61.0% (specificity) of PCS non-responders (<5points) with ROC-AUC=0.61. Serious adverse events (AEs) occurred in 1.8% of patients; the most common AEs were infections (7.7%). Conclusion : We demonstrated clinical and HRQoL improvements over 6 months in a large, real-world population of AS patients newly treated with GLM or IFX; higher ASDAS, elevated CRP, and younger age were associated with improvements in HRQoL and an overall more robust response.