Construction of a dynamic nomogram to predict osteoporosis in elderly maintenance hemodialysis patients based on microinflammatory indicators

Objective To construct a dynamic nomogram （DynNom） to predict osteoporosis in elderly maintenance hemodialysis patients based on the microinflammatory indicators of high-sensitivity C reactive protein （hs-CRP） and procalcitonin （PCT）.Methods Elderly maintenance hemodialysis patients admitted to Nanjing Lishui People's Hospital （Zhongda Hospital Lishui Branch， Southeast University） from January 1， 2020 to January 31， 2023 and from February 1 to April 30， 2023 were selected and enrolled in the training set （n=161） and validation set （n=37）. Patients in the training set were divided into the osteoporosis group （n=71） and non-osteoporosis group （n=90） according to the occurrence of osteoporosis. Clinical data of the patients were collected. Univariate and multivariate regression analyses were performed to identify factors affecting osteoporosis in elderly patients with maintenance dialysis. The values of hs-CRP and PCT in predicting osteoporosis in elderly maintenance hemodialysis patients were assessed using receiver operating characteristic （ROC） curves， and the DynNom was established accordingly.Results There were no significant differences in the gender， age， smoking history， primary disease， duration of chronic renal failure， blood calcium， blood phosphorus， blood potassium， whole segment parathyroid hormone， creatinine， uric acid， and alkaline phosphatase between the osteoporosis group and non-osteoporosis group （P>0.05）. The percentage of patients in the osteoporosis group with body mass index （BMI） <18.5 kg/m² （23.94% vs 8.89%）， dialysis duration≥24 months （32.39% vs 14.44%）， albumin <35 g/L （22.54% vs 7.78%）， hemoglobin <110 g/L （47.89% vs 25.56%）， hs-CRP ［（7.30±1.67）mg/L vs （6.82±1.20）mg/L］ and PCT ［（19.87±3.28）ng/L vs （18.16±3.34）ng/L］ were significantly higher than those of the non-osteoporotic group （P<0.05）. BMI <18.5 kg/m²， and longer duration of dialysis， albumin <35 g/L， hemoglobin <110 g/L， and higher hs-CRP and PCT were independent risk factors for osteoporosis in elderly maintenance hemodialysis patients （P<0.05）. The area under the curve （AUC） of hs-CRP and PCT in predicting osteoporosis in elderly maintenance hemodialysis patients was 0.597 （95%CI： 0.506-0.688） and 0.636 （95% CI： 0.551-0.722）， respectively. Validation of the DynNom showed that the consistency of the training and validation sets was 0.801 （95%CI： 0.767-0.835） and 0.793 （95%CI： 0.752-0.821）， respectively， with the two sets of calibration curves converged to the ideal curve. The AUC was 0.807 （95%CI： 0.872-0.842） in the training set and 0.797 （95%CI： 0.868-0.837） in the validation set. The decision curves of the two sets showed that the net benefit value of the model was ≥0 within the range of 0 to 100% prediction.Conclusion BMI <18.5 kg/m²， longer duration of dialysis， albumin <35 g/L and hemoglobin <110 g/L are positively correlated with the risk of osteoporosis in elderly maintenance hemodialysis patients. hs-CRP and PCT have some predictive value for osteoporosis in elderly maintenance hemodialysis patients. The DynNom created based on hs-CRP and PCT can effectively predict the risk of osteoporosis in elderly maintenance hemodialysis patients.