Time to mobilization in hours after surgery for hip fracture and 30-day mortality-A study on 36,229 patients from the Danish Hip Fracture Registry.

BACKGROUND Early mobilization after hip fracture (HF) is a key indicator in national registries and associated with reduced mortality, but in-depth analysis of time in hours for mobilization is lacking. We described the clinical profile and 30-day mortality by time-intervals in hours for mobilization after HF surgery. METHODS Using Danish registries, we included HF patients aged ≥65 years (from year 2016-2021). Exposure-time in hours from start of surgery to mobilization. Outcome-mortality within 2-30 days of surgery. Primary mortality analysis-we compared mobilizations >24-36h versus ≤24h by calculating weighted risks, risk differences (RD) and hazard ratios (HR) using inverse probability of treatment weighted method. Secondary mortality analyses-we compared mobilizations >24-36h and >12-24h versus ≤12h. RESULTS We included 36,229 patients (67.3% women) with a median age of 82.6 years. Patients mobilized ≤24h had similar age, BMI, and marital status, but were slightly more living in own residence, have high pre-fracture mobility, high education, and less comorbidity than patients mobilized >24-36h. The weighted risk of 30-day mortality for mobilization >24-36h versus ≤24h was 10.43% and 7.89% with corresponding RD and HR of 1.67 (0.54,2.80) and 1.22 (1.07,1.38). The weighted RD and HR were 1.62% (0.89, 2.35) and 1.25 (1.12,1.39) for >12-24 versus ≤12h, and 1.33% (0.17-2.49) and 1.16 (1.02,1.31) for >12-24h versus >24-36h. CONCLUSION The 30-day mortality increases with the increasing time to mobilization after HF surgery. We suggest focusing on time in hours to mobilization with a 24-hour or even earlier timepoint after surgery.