Background. Chronic kidney disease (CKD) patients affected by mineral bone disorders (MBD) have higher rates of all-cause and cardiovascular-related mortality. Approximately, one-third of dialysis patients have low serum parathyroid hormone (PTH) levels (≤150 pg/mL). However, the reason why these patients have higher mortality compared to patients with normal PTH levels has not yet been fully elucidated. Methods. The FARO study was performed on 2453 Italian patients followed prospectively from 28 dialysis centres over a 2-year period. Data were collected every 6 months and end points included time-to-death cumulative probability in patients with serum intact PTH (iPTH) ≤150 pg/mL and the effect of vitamin D receptor activation (VDRA) therapy. KaplanMeier curves and proportional hazards regression models stratified by PTH levels (i.e. ≤150 and >150 pg/mL) were used to determine cumulative probability of time-to-death and adjusted hazard ratios (HRs) for demographic, clinical and CKD-MBD treatment characteristics. Results. The cumulative probability of death was higher (P <0.01) for patients with serum iPTH levels ≤150 pg/mL [25.1%, 95% confidence interval (CI): 22.128.5 at 18 months] versus those with serum iPTH levels within the normal range (18.0%, 95% CI: 16.120.1). In a model with time-dependent covariates restricted to time periods when patients had iPTH levels ≤150 pg/mL, lower mortality was observed in patients treated with VDRA [i.e. HR 0.62, 95% CI: 0.420.92 for oral or intravenous (IV) calcitriol; HR 0.18, 95% CI: 0.040.8 for IV paricalcitol] versus those not receiving any VDRA (P <0.01) independently of other variables. Patients who received IV paricalcitol, compared with either oral or IV calcitriol, showed reduced mortality, but this was not statistically significant (HR = 0.3, 95% CI: 0.071.31, P = 0.11). Conclusion. Results from this observational study suggest that VDRA therapy was associated with improved survival in dialysis patients, even with low serum iPTH levels.
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