Table 5.
Predictor | β | SE β | Wald | df | p value | Odds ratio | 95% CIa | |
---|---|---|---|---|---|---|---|---|
lower | upper | |||||||
Constant | 0.868 | 3.578 | 0.059 | 1 | 0.808 | 2.381 | – | – |
CASR genotype (1 = G carrier, 0 = noncarrier) | 1.378 | 0.529 | 6.786 | 1 | 0.009 | 3.968 | 1.262 | 21.179 |
bPTH (*100 pg/mL) | 0.039 | 0.065 | 0.352 | 1 | 0.553 | 1.039 | 0.896 | 1.241 |
bPhos (mg/dL) | -0.388 | 0.168 | 5.309 | 1 | 0.021 | 0.679 | 0.483 | 0.869 |
bCa (mg/dL) | -0.426 | 0.288 | 2.199 | 1 | 0.138 | 0.653 | 0.319 | 1.134 |
bCtriol (μg/week) | 0.772 | 0.226 | 11.668 | 1 | 0.001 | 2.165 | 1.357 | 4.899 |
bErgo (*20,000 IU/month) | 0.065 | 0.053 | 1.511 | 1 | 0.219 | 1.067 | 0.945 | 1.249 |
AGE (years) | 0.052 | 0.018 | 8.284 | 1 | 0.004 | 1.053 | 1.014 | 1.121 |
The dependent variable in this analysis is achievement of at least 30% reduction of PTH from baseline value (1 = at least 30% PTH reduction and 0 = less than 30% PTH reduction from baseline); Predicted logit of achieving 30% PTH reduction = 0.868 + 1.378 (if G carrier) + 0.039 (bPTH in *100 pg/mL)—0.388 (bPhos in mg/dL)—0.426 (bCa in mg/dL) + 0.772 (bCtriol in μg/week) + 0.065 (bErgo in *20,000 IU/month) + 0.052 (AGE in years); All tested continuous variables were linearly related to the logit of the dependent variable (Box-Tidwell test, all p > 0.05); Omnibus test of model coefficients, chi-square = 45.940, df = 7, p < 0.001; Nagelkerke R square = 0.388; Hosmer and Lemeshow test, chi-square = 14.753, df = 8, p = 0.064; With the cutoff set at 0.5 for prediction of 30% PTH reduction achievement, the model was able to correctly classify 79.7% of those who achieved at least 30% iPTH reduction and 62.5% of those who did not, for the overall correction prediction of 72.6%
β the partial logistic regression coefficient, SE β the standard errors of the partial slope coefficient, df degree of freedom, AGE age on the day of starting cinacalcet, bCa baseline serum calcium concentration, bCtriol baseline calcitriol dose or relative calcitriol equivalent dose of alfacalcidol, bErgo ergocalciferol dose before starting cinacalcet, bPhos baseline serum phosphate concentration, bPTH baseline serum intact parathyroid hormone concentration.
a95% confidence interval of the odds ratio from bootstrapping, based on 5000 bootstrap samples.