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Is serum phosphorus control related to parathyroid hormone control in dialysis patients with secondary hyperparathyroidism?

Frazão JM, Braun J, Messa P, Dehmel B, Mattin C, Wilkie M - BMC Nephrol (2012)

Bottom Line: Patients who achieved iPTH ≤ 300 pg/mL (or a reduction of ≥ 30% from baseline) were more likely to achieve serum P targets than those who did not, regardless of treatment group.Of those who did achieve iPTH ≤ 300 pg/mL, 43% achieved P ≤ 4.5 mg/dL and 70% achieved P ≤ 5.5 mg/dL, versus 21% and 46% of those who did not achieve iPTH ≤ 300 pg/mL.This post hoc analysis found that control of serum P in dialysis patients was better when serum PTH levels were lowered effectively, regardless of treatment received.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nephrology, Hospital de S, João, Medical School & Nephrology Research & Development Unit, University of Porto, Porto, Portugal. jmmdfrazao@netcabo.pt

ABSTRACT

Background: Elevated serum phosphorus (P) levels have been linked to increased morbidity and mortality in dialysis patients with secondary hyperparathyroidism (SHPT) but may be difficult to control if parathyroid hormone (PTH) is persistently elevated. We conducted a post hoc analysis of data from an earlier interventional study (OPTIMA) to explore the relationship between PTH control and serum P.

Methods: The OPTIMA study randomized dialysis patients with intact PTH (iPTH) 300-799 pg/mL to receive conventional care alone (vitamin D and/or phosphate binders [PB]; n=184) or a cinacalcet-based regimen (n=368). For patients randomized to conventional care, investigators were allowed flexibility in using a non-cinacalcet regimen (with no specific criteria for vitamin D analogue dosage) to attain KDOQI™ targets for iPTH, P, Ca and Ca x P. For those assigned to the cinacalcet-based regimen, dosages of cinacalcet, vitamin D sterols, and PB were optimized over the first 16 weeks of the study, using a predefined treatment algorithm. The present analysis examined achievement of serum P targets (≤ 4.5 and ≤ 5.5 mg/dL) in relation to achievement of iPTH ≤ 300 pg/mL during the efficacy assessment phase (EAP; weeks 17-23).

Results: Patients who achieved iPTH ≤ 300 pg/mL (or a reduction of ≥ 30% from baseline) were more likely to achieve serum P targets than those who did not, regardless of treatment group. Of those who did achieve iPTH ≤ 300 pg/mL, 43% achieved P ≤ 4.5 mg/dL and 70% achieved P ≤ 5.5 mg/dL, versus 21% and 46% of those who did not achieve iPTH ≤ 300 pg/mL. Doses of PB tended to be higher in patients not achieving serum P targets. Patients receiving cinacalcet were more likely to achieve iPTH ≤ 300 pg/mL than those receiving conventional care (73% vs 23% of patients). Logistic regression analysis identified lower baseline P, no PB use at baseline and cinacalcet treatment to be predictors of achieving P ≤ 4.5 mg/dL during EAP in patients above this threshold at baseline.

Conclusions: This post hoc analysis found that control of serum P in dialysis patients was better when serum PTH levels were lowered effectively, regardless of treatment received.

Trial registration: Clinicaltrials.gov identifier NCT00110890.

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Related in: MedlinePlus

Evolution of relative vitamin D dose (mean ± standard error; SE) by iPTH achievement category (≤ vs > 300 pg/mL) during the efficacy assessment phase (EAP). Note that this shows vitamin D dose over time for all patients still on study. If a patient is not receiving vitamin D at a particular timepoint their relative dose will be zero and will be included as such in the calculation of mean relative dose. See text for explanation of mean relative dose. Values shown on graph do not exactly match values reported in the text because imputation is used for calculating values in the text.
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Figure 3: Evolution of relative vitamin D dose (mean ± standard error; SE) by iPTH achievement category (≤ vs > 300 pg/mL) during the efficacy assessment phase (EAP). Note that this shows vitamin D dose over time for all patients still on study. If a patient is not receiving vitamin D at a particular timepoint their relative dose will be zero and will be included as such in the calculation of mean relative dose. See text for explanation of mean relative dose. Values shown on graph do not exactly match values reported in the text because imputation is used for calculating values in the text.

Mentions: The relationship of vitamin D use to serum phosphorus achievement was less consistent, but patients who were failing to meet the PTH target were receiving higher vitamin D doses [Table 4]. There was a significant increase in mean relative vitamin D dose, from 1.6 at baseline to 1.8 at the end of the EAP, in patients not achieving the iPTH target (mean change 0.2; p = 0.04). In those achieving the iPTH target, mean relative vitamin D dose decreased, from 1.6 to 1.4, although this change was not statistically significant (mean change −0.1; p = 0.18). Figure 3 shows a divergence in mean relative vitamin D dose between the two PTH target achievement categories during the EAP, although it must be noted that patient numbers decreased between baseline and EAP.


Is serum phosphorus control related to parathyroid hormone control in dialysis patients with secondary hyperparathyroidism?

Frazão JM, Braun J, Messa P, Dehmel B, Mattin C, Wilkie M - BMC Nephrol (2012)

Evolution of relative vitamin D dose (mean ± standard error; SE) by iPTH achievement category (≤ vs > 300 pg/mL) during the efficacy assessment phase (EAP). Note that this shows vitamin D dose over time for all patients still on study. If a patient is not receiving vitamin D at a particular timepoint their relative dose will be zero and will be included as such in the calculation of mean relative dose. See text for explanation of mean relative dose. Values shown on graph do not exactly match values reported in the text because imputation is used for calculating values in the text.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3473247&req=5

Figure 3: Evolution of relative vitamin D dose (mean ± standard error; SE) by iPTH achievement category (≤ vs > 300 pg/mL) during the efficacy assessment phase (EAP). Note that this shows vitamin D dose over time for all patients still on study. If a patient is not receiving vitamin D at a particular timepoint their relative dose will be zero and will be included as such in the calculation of mean relative dose. See text for explanation of mean relative dose. Values shown on graph do not exactly match values reported in the text because imputation is used for calculating values in the text.
Mentions: The relationship of vitamin D use to serum phosphorus achievement was less consistent, but patients who were failing to meet the PTH target were receiving higher vitamin D doses [Table 4]. There was a significant increase in mean relative vitamin D dose, from 1.6 at baseline to 1.8 at the end of the EAP, in patients not achieving the iPTH target (mean change 0.2; p = 0.04). In those achieving the iPTH target, mean relative vitamin D dose decreased, from 1.6 to 1.4, although this change was not statistically significant (mean change −0.1; p = 0.18). Figure 3 shows a divergence in mean relative vitamin D dose between the two PTH target achievement categories during the EAP, although it must be noted that patient numbers decreased between baseline and EAP.

Bottom Line: Patients who achieved iPTH ≤ 300 pg/mL (or a reduction of ≥ 30% from baseline) were more likely to achieve serum P targets than those who did not, regardless of treatment group.Of those who did achieve iPTH ≤ 300 pg/mL, 43% achieved P ≤ 4.5 mg/dL and 70% achieved P ≤ 5.5 mg/dL, versus 21% and 46% of those who did not achieve iPTH ≤ 300 pg/mL.This post hoc analysis found that control of serum P in dialysis patients was better when serum PTH levels were lowered effectively, regardless of treatment received.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nephrology, Hospital de S, João, Medical School & Nephrology Research & Development Unit, University of Porto, Porto, Portugal. jmmdfrazao@netcabo.pt

ABSTRACT

Background: Elevated serum phosphorus (P) levels have been linked to increased morbidity and mortality in dialysis patients with secondary hyperparathyroidism (SHPT) but may be difficult to control if parathyroid hormone (PTH) is persistently elevated. We conducted a post hoc analysis of data from an earlier interventional study (OPTIMA) to explore the relationship between PTH control and serum P.

Methods: The OPTIMA study randomized dialysis patients with intact PTH (iPTH) 300-799 pg/mL to receive conventional care alone (vitamin D and/or phosphate binders [PB]; n=184) or a cinacalcet-based regimen (n=368). For patients randomized to conventional care, investigators were allowed flexibility in using a non-cinacalcet regimen (with no specific criteria for vitamin D analogue dosage) to attain KDOQI™ targets for iPTH, P, Ca and Ca x P. For those assigned to the cinacalcet-based regimen, dosages of cinacalcet, vitamin D sterols, and PB were optimized over the first 16 weeks of the study, using a predefined treatment algorithm. The present analysis examined achievement of serum P targets (≤ 4.5 and ≤ 5.5 mg/dL) in relation to achievement of iPTH ≤ 300 pg/mL during the efficacy assessment phase (EAP; weeks 17-23).

Results: Patients who achieved iPTH ≤ 300 pg/mL (or a reduction of ≥ 30% from baseline) were more likely to achieve serum P targets than those who did not, regardless of treatment group. Of those who did achieve iPTH ≤ 300 pg/mL, 43% achieved P ≤ 4.5 mg/dL and 70% achieved P ≤ 5.5 mg/dL, versus 21% and 46% of those who did not achieve iPTH ≤ 300 pg/mL. Doses of PB tended to be higher in patients not achieving serum P targets. Patients receiving cinacalcet were more likely to achieve iPTH ≤ 300 pg/mL than those receiving conventional care (73% vs 23% of patients). Logistic regression analysis identified lower baseline P, no PB use at baseline and cinacalcet treatment to be predictors of achieving P ≤ 4.5 mg/dL during EAP in patients above this threshold at baseline.

Conclusions: This post hoc analysis found that control of serum P in dialysis patients was better when serum PTH levels were lowered effectively, regardless of treatment received.

Trial registration: Clinicaltrials.gov identifier NCT00110890.

Show MeSH
Related in: MedlinePlus