Parathyroid Hormone Levels as an Independent Predictor of Ischemic Heart Disease in Stage 3–5 Non-Dialysis Chronic Kidney Disease: A Retrospective Cohort Study

<b>Background</b>: Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a key contributor to complications, including ischemic heart disease (IHD), which significantly elevates mortality in patients with chronic kidney disease (CKD). This study aims to identify factors associated with IHD risk in pre-dialysis CKD and establish the minimum parathyroid hormone (PTH) threshold necessary to mitigate this risk. <b>Methods</b>: We retrospectively analyzed data from CKD stage 3-5ND patients aged over 18 years, followed from 2018 to 2022. IHD was identified using ICD-10 codes. An adjusted Cox regression model and joint modeling analysis were used to assess the association between risk factors and IHD. <b>Results:</b> A total of 1210 CKD patients were included in the analysis, with a median follow-up duration of 513.5 days (IQR 189-979). The incidence of IHD was 7.5%. PTH levels ≥166 ng/L (HR 1.87, 95% CI 1.05-3.35, <i>p</i> = 0.03) and age ≥65 years (HR 1.68, 95% CI 1.003-2.81, <i>p</i> = 0.04) were significantly associated with an increased risk of IHD. In joint modeling analysis, time-varying PTH, age ≥65 years, and diabetes mellitus (DM) were significantly associated with an increased risk of IHD, whereas ARB and statin use were associated with a reduced risk. Calcium and phosphate levels did not demonstrate significant associations with IHD risk. <b>Conclusions:</b> Baseline PTH levels ≥166 ng/L and time-varying PTH were independently and significantly associated with an increased risk of IHD. In contrast, calcium and phosphate levels showed no significant association with IHD risk.