Association Between Immediate Postoperative Pulse Pressure and Three-Year All-Cause Mortality After Hip Fracture Surgery in Older Adults: A Post Hoc Analysis of a Prospective Cohort

Objectives: The prognostic relevance of postoperative blood pressure after return to the ward is unclear. In this exploratory post hoc analysis, we investigated the associations of postoperative systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and pulse pressure (PP) with three-year all-cause mortality in older hip fracture patients. Methods: This single-centre post hoc analysis used prospectively collected data from patients aged 65 years or older who underwent hip fracture surgery under neuraxial anaesthesia between November 2018 and November 2019. Immediate postoperative blood pressure was defined as the first non-invasive cuff measurement recorded after return to the ward. PP was calculated as SBP minus DBP, and MAP as (SBP + 2 × DBP)/3. All 1052 patients were included in time-to-event analyses; patients lost to follow-up were right-censored on the date they were last known to be alive. Each blood pressure parameter was assessed in a separate adjusted Cox proportional hazards model. Restricted cubic splines were used to assess nonlinearity. Results: Among 865 patients with known three-year vital status, 192 had died and 673 were alive; 187 patients were censored before three years. Mean PP was lower among patients who died than among survivors (58.68 mmHg (SD 19.45) vs. 62.46 mmHg (SD 20.81); p = 0.019). Each 10 mmHg increase in PP was associated with a lower hazard of mortality (adjusted hazard ratio (HR) 0.914, 95% confidence interval (CI) 0.834 to 0.990; p = 0.033). Spline analysis showed an overall association for PP (p = 0.033), with no evidence of nonlinearity (p = 0.201). Continuous SBP, DBP, and MAP, and DBP < 60 mmHg were not independently associated with mortality. Conclusions: In this exploratory post hoc analysis, lower immediate postoperative PP was associated with a higher risk of three-year all-cause mortality. But PP should not be interpreted as a causal or therapeutic target.