Correlation Between Serum Creatinine-to-Cystatin C Ratio and Prognosis of Patients with Hip Fracture

Abstract

Objective: This study aimed to investigate the association between the serum creatinine-to-cystatin C ratio (CCR) and the prognosis of patients with hip fracture.

Methods: This retrospective cohort study included patients who underwent hip fracture surgery at a tertiary hospital in China between January 2018 and December 2023. CCR was calculated from the preoperative serum creatinine and cystatin C levels. The primary outcome was 1-year mortality after surgery in patients with hip fracture and the secondary outcome was 6-month mortality. The associations between preoperative CCR and prognosis of patients were assessed using Kaplan-Meier curves, Cox regression models, interactions, and stratified analyses.

Results: A total of 1914 patients who underwent surgery for hip fracture were included. The mean age of the participants was 73.4 ± 14.0 years and the median CCR was 7.3 (6.3-8.5). The prevalence of 1-year mortality flowing hip fracture surgery was 7.3%. Multivariate Cox regression analysis indicated that a high CCR was independently associated with reduced 6-month mortality [hazard ratio (HR) = 0.51; 95% confidence interval (CI) = 0.31-0.84] and 1-year mortality (HR = 0.61; 95% CI = 0.42-0.90) after adjusting for covariates. In addition, Kaplan-Meier curve analyses indicated that the low CCR group had higher 6-month and 1-year mortality rates (all P<0.0001). Subgroup analyses showed that a high CCR was independently associated with reduced 1-year mortality after hip surgery in patients with diabetes (HR = 0.39; 95% CI = 0.17-0.89), males (HR = 0.48; 95% CI = 0.26-0.86) and those without hypertension (HR = 0.55; 95% CI = 0.32-0.97) or cardiovascular disease (HR = 0.54; 95% CI = 0.34-0.84).

Conclusion: Our study found that a low CCR was associated with poor prognosis in patients undergoing hip fracture surgery. Further research is needed to clarify the mechanism linking low CCR to poor prognosis in hip fracture patients.

Keywords: creatinine-to-cystatin C ratio; hip fracture; mortality; surgery.

Figure 1

Flowchart of study population.

Figure 2

Curve fitting of CCR and 1-year mortality in patients with Hip fracture surgery. Data were fit by a Cox proportional hazard regression model based on restricted cubic splines. P-value for non-linearity derived from Likelihood Ratio Test. CCR was entered as continuous variable. Data were adjusted for the factors (age, gender, BMI, ASA physical status, time to admission, alcohol history, smoking history, hypertension, diabetes, cardiovascular disease, lung disease, albumin, glucose, d-dimer, APTT, hemoglobin, neutrophil count, and leucocyte count). The curves line and shaded areas around depict the estimated values and their corresponding 95% confidence intervals. Curves below depict the distribution of the CCR.

Figure 3

Kaplan–Meier curve of mortality for patients with Hip fracture surgery. (A) Kaplan–Meier curve of 6-month mortality after hip fracture surgery, (B) Kaplan–Meier curve of 1-year mortality after hip fracture surgery. P-value derived from Log Rank Test.

Figure 4

Association between CCR and 1-year mortality in subgroups for patients with Hip fracture surgery. Low CCR was the reference for high CCR. Each stratification adjusted for the factors (age, gender, BMI, ASA physical status, time to admission, alcohol history, smoking history, hypertension, diabetes, cardiovascular disease, lung disease, albumin, glucose, d-dimer, APTT, hemoglobin, neutrophil count, and leucocyte count) in the multivariable Cox regression, except for the stratification factor itself.