Patients who did not regain their prefracture mobility prior to hospital discharge following hip fracture surgery may have a higher risk of mortality through the first year, although they did not have a consistently higher risk of reoperation, according to a nationwide Danish cohort study.
Investigators analyzed data from 33,486 patients aged 65 years or older who underwent surgery for a first-time unilateral low-energy hip fracture between January 2016 and November 2021. Mobility was assessed using the Cumulated Ambulation Score, measuring independence in getting in and out of bed, sit-to-stand-to-sit from a chair with armrests, and indoor walking. The primary exposure was whether patients regained their prefracture mobility by discharge. Reoperation within 30 days and 1 year was the primary outcome, and all-cause mortality at the same time points was a key secondary outcome.
Among the 29,650 patients with complete mobility data, 65% did not regain their prefracture mobility by discharge. Mortality differed substantially between the groups. For instance, 30-day mortality was 9% among patients who did not regain mobility compared with 3% among those who did. After adjustment for age, sex, comorbidities, year of surgery, and length of stay, failure to regain mobility was associated with about twice the likelihood of mortality within 30 days. At 1 year, mortality was 29% among the patients who did not regain mobility vs. 12% among those who did recover their prefracture mobility, corresponding to a 77% higher likelihood of mortality.
The investigators also found evidence of a dose-response relationship. Mortality increased progressively as mobility loss worsened, both at 30 days and 1 year. Compared with the patients who regained their prefracture mobility, all categories of mobility decline were associated with higher mortality, with the greatest risks observed among those who experienced the largest decreases in mobility scores.
In contrast, mobility recovery was not consistently associated with reoperation risk. At 30 days, the patients who lost one to two points on the mobility scale had a modestly higher risk of reoperation compared with those who regained their prefracture mobility. However, this association did not persist at 1 year, and larger declines in mobility were not associated with higher reoperation rates. Overall, adjusted analyses showed no statistically significant difference in reoperation risk between the patients who did and did not regain their prefracture mobility.
Additional analyses showed that the relationship between mobility decline and reoperation was generally similar across age groups, sex, and living arrangements. The highest reoperation rates were observed among patients with a 1- to 2-point declines in their Cumulated Ambulation Score, but the pattern was not consistent across longer follow-up. The investigators found that the patients with missing mobility data also had higher mortality rates compared with patients with complete mobility assessments.
The investigators noted several limitations. As an observational study, the analysis could not determine whether impaired mobility directly contributed to mortality or instead reflected factors such as frailty, comorbidity burden, postoperative complications, or differences in rehabilitation and care pathways. The investigators noted that decisions regarding reoperation may be influenced by competing mortality risk and treatment preferences in frail patients, potentially obscuring associations between mobility status and surgical complications.
The findings suggested that mobility status at discharge may serve as a prognostic marker following hip fracture surgery, particularly for mortality risk.
“The limited association between impaired mobility and reoperation may reflect competing mortality risk and clinical decision-making in frail patients rather than the absence of postoperative complications. In perspective, these findings underscore that postoperative mobility decline on discharge is a strong prognostic indicator of mortality.,” wrote lead study author Simon Storgaard Jensen, of the Department of Clinical Epidemiology at Aarhus University Hospital and the Department of Clinical Medicine at Aarhus University in Denmark, and colleagues.
The study authors reported no external funding and declared no conflicts of interest.
Source: Acta Orthopaedica
