Multidimensional prognostic index and the risk of fractures: an 8-year longitudinal cohort study in the Osteoarthritis Initiative

SUMMARY: In this longitudinal study, with a follow-up of 8 years, multidimensional prognostic index (MPI), a product of the comprehensive geriatric assessment, significantly predicted the onset of fractures in older people affected by knee osteoarthritis. PURPOSE: Frailty may be associated with higher fracture risk, but limited research has been carried out using a multidimensional approach to frailty assessment and diagnosis. The present research aimed to investigate whether the MPI, based on comprehensive geriatric assessment (CGA), is associated with the risk of fractures in the Osteoarthritis Initiative (OAI) study. METHODS: Community-dwellers affected by knee OA or at high risk for this condition were followed-up for 8 years. A standardized CGA including information on functional, nutritional, mood, comorbidity, medication, quality of life, and co-habitation status was used to calculate the MPI. Fractures were diagnosed using self-reported information. Cox’s regression analysis was carried out and results are reported as hazard ratios (HRs), with their 95% confidence intervals (CIs), adjusted for potential confounders. RESULTS: The sample consisted of 4024 individuals (mean age 61.0 years, females = 59.0%). People with incident fractures had a significant higher MPI baseline value than those without (0.42 ± 0.18 vs. 0.40 ± 0.17). After adjusting for several potential confounders, people with an MPI over 0.66 (HR = 1.49; 95%CI: 1.11–2.00) experienced a higher risk of fractures. An increase in 0.10 point in MPI score corresponded to an increase in fracture risk of 4% (HR = 1.04; 95%CI: 1.008–1.07). Higher MPI values were also associated with a higher risk of non-vertebral clinical fractures. CONCLUSION: Higher MPI values at baseline were associated with an increased risk of fractures, reinforcing the importance of CGA in predicting fractures in older people affected by knee OA.