The Role of Prefracture Health Status in Physical and Mental Function After Hip Fracture Surgery.

ABSTRACT

OBJECTIVES: To examine the associations of 3 measures of prefracture health status (physical function, mental function, and comorbidity count) with trajectories of physical and mental function at 1.5, 3, 6, and 12 months after hip fracture surgery. DESIGN: Single-center observational study. SETTING: Singapore General Hospital (an acute hospital). PARTICIPANTS: Patients aged ≥60 years who underwent first hip fracture surgery between June 2011 and July 2016 (N = 928). INTERVENTION None. MEASUREMENTS We used data collected prospectively from the hospital's hip fracture registry. We used the Short Form-36 (SF-36) Physical Component Summary (PCS) and Mental Component Summary (MCS) as indicators of physical and mental function, respectively, collected at admission and at 1.5, 3, 6, and 12 months after hip fracture surgery. Comorbidity count at admission was the sum from a list of 10 common diseases associated with poorer physical function. RESULTS: Prefracture physical function and prefracture mental function demonstrated time-varying associations (interaction P < .001 and P = .001, respectively) with postfracture physical function; the associations were small initially but increased in strength up to 6 months and stabilized thereafter. In contrast, the strength of the association between comorbidity count and postfracture physical function were time-invariant (-0.52, P = .027). The strength of the associations between all 3 measures of prefracture health status and postfracture mental function were also constant over time (0.09, P = .004, for physical function; 0.38, P < .001, for mental function; -0.70, P = .034, for comorbidity count). CONCLUSIONS/IMPLICATIONS The time-varying associations between prefracture health status and postfracture physical function suggest that even for patients with good prefracture health status, initial recovery may be slow. Our findings can be useful to clinicians and therapists in their prognostic evaluations and in management of patients' expectation for recovery.