Care-Need Level Worsening After Hip Fracture Surgery in Kyoto, Japan: Population-Based Cohort Study
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Published on: September 7, 2022
Kosuke Sasaki1, Yoshimitsu Takahashi2, Yoshitaka Nishikawa1
1Department of Health Informatics, School of Public Health, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Objectives:
To describe 3-year transitions of care-need level after hip fracture surgery and identify factors associated with subsequent nonfatal worsening among day-180 survivors.
Design:
Retrospective cohort study using linked administrative medical and long-term care insurance claims.
Setting And Participants:
Adults aged ≥75 years in Kyoto City, Japan, who underwent hip fracture surgery between 2013 and 2018. The day-180 landmark cohort included 6556 patients who survived to day 180 and were not certified as care-need level 5 before surgery or at the landmark.
Methods:
Follow-up started at day 180. The primary estimand was subsequent nonfatal care-need level worsening among patients alive and still at risk at the landmark; death after the landmark was treated as a competing event. We estimated cumulative incidence functions and Fine-Gray models with covariate-by-log-time interactions. Supplementary analyses examined a death-inclusive composite end point and alternative landmarks.
Results:
The cumulative incidence of worsening was 10.6% at 12 months, 28.3% at 24 months, and 37.4% at 36 months after surgery. Longer initial claims-based rehabilitation continuity during the postoperative 6 months was associated with a lower incidence of subsequent nonfatal worsening (adjusted subdistribution hazard ratio per month, 0.961; 95% CI, 0.941-0.982). The supplementary composite end point analysis showed no clear association between rehabilitation continuity and worsening or death (hazard ratio, 0.988; 95% CI, 0.972-1.006). Associations of higher Hospital Frailty Risk Score and preoperative care-need levels with worsening varied over time.
Conclusions And Implications:
Among day-180 survivors after hip fracture surgery, preoperative frailty and care-need levels showed time-varying associations with subsequent nonfatal worsening. Longer initial claims-based rehabilitation continuity was associated with lower incidence of nonfatal worsening but should be interpreted as a claims-based association, not evidence of a causal effect or mortality-inclusive benefit. These findings support ongoing risk assessment and periodic reassessment of care needs beyond the early postoperative period.