Low levels of PTH predict early mortality in incident patients on hemodialysis: results from a large cohort

Abstract Purpose: Parathyroid hormone (PTH) is merit as a risk factor for mortality in patients with chronic kidney disease starting dialysis in a U-shape. Most studies, however, do not focus on incident patients and those who died within the first 90 days of therapy. We evaluated PTH as a risk factor for mortality in a large cohort population in Brazil. Methods: This is an observational cohort study that included 4,317 adult patients who initiated hemodialysis between July 1st, 2012, and June 30, 2017. The main outcome was all-cause mortality. Fine-gray sub-distribution hazard models were used to evaluate survival in the presence of a competing event (kidney transplant). Results: median PTH levels of 252 (118, 479) pg/mL. There were 331 deaths during the first 90 days of therapy (6.7%), 430 in a 1-year follow-up (10.7%) and 1,282 (32%) during the 5-year study period. Deaths according to PTH < 150, 150-600 and > 600 pg/mL corresponded to 38.1%, 33.0% and 28.5%, respectively (p <0.001). In an adjusted model, patients who started dialysis with PTH < 150 pg/mL had a higher mortality risk within the first 90 days, but not in 1 year and 5 years after starting dialysis. Analyses in a subset of patients with a repeated PTH in 1 year (N=1,954) showed that although persistent PTH low levels (<150 pg/mL) at 1 year were significantly associated with all-cause mortality this result was not sustained after multiple adjustments. Conclusion: PTH <150 pg/mL confers a high mortality risk in the first 90 days of dialysis. If this result reflects poor nutritional conditions deserves further investigation.