Modelling the Functional Comorbidity Index as a predictor of health-related quality of life in patients with glenoid labrum disorders

Background/aim Health-related quality of life (HRQoL) is increasingly assessed within orthopaedic research. For those patients presenting with glenoid labral pathologies, there is little information on how baseline comorbidities affect long-term outcomes and HRQoL. This study aimed to investigate a model, including baseline comorbidities and demographics, to predict change in 2-year HRQoL scores in adult patients with glenoid labral tears or degenerations. Methods Participants provided Functional Comorbidity Index (FCI) scores and self-completed the Western Ontario Rotator Cuff (WORC) index at 6, 12 and 24 months. Univariable and multivariable linear regressions were performed to assess predictive quality of baseline comorbidities and demographics on the primary outcome measure of interest (change in WORC score). Results Multivariate regression with a continuous scaled FCI (β=617.8, p=0.042), age (by decade) (β=297, p<0.01), surgical group (β=-476.69, p<0.01) and an interaction term between FCI and age (β=-103.65, p=0.03) were significant predictors of change in WORC scores at 2-year follow-up (r2=0.293858). Multivariate regression with FCI scaled categorically reported only patients with three comorbidities (β=-454.06, p=0.057) and age (by decade) (β=156.87, p=0.04) as the only significant predictors of change in WORC scores at 2-year follow-up (r2=0.1279). Conclusion The continuous FCI model is better suited to predict future WORC and HRQoL scores among this patient population. Patients reporting with higher numbers of baseline comorbidities improved significantly more than patients with fewer comorbidities. This information on expected change in HRQoL scores among patients with a wide range of FCI scores at baseline may help guide treatment decisions based on these criteria.