Table 2.
Change in parameters across treatment arms over the 6-month study duration
| Parameter | Placebo | Ergocalciferol | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Baseline Value | Month 3 Value | Month 6 Value | Model Slopec (95% CI) | Within-Group P Valued | Baseline Value | Month 3 Value | Month 6 Value | Model Slopec (95%CI) | Within-Group P Valued | Between-Group P Valuee | |
| Serum 25(OH)D (ng/ml) | 16.9±6.4 | 17.3±7.0 | 17.5±7.4 | −0.07 (–0.44 to 0.29) | 0.70 | 16.0±5.9 | 41.0±15.6 | 39.2±14.9 | 4.2 (3.8 to 4.5) | <0.001 | <0.001 |
| Epoetin dose (units/week)a | 5400 (2400, 11,500) | 6000 (2000, 10,800) | 6050 (2000, 11,800) | 0.98 (0.94 to 1.02) | 0.42 | 5800 (2600, 12,200) | 6000 (2600, 10,600) | 7000 (2500, 16,000) | 0.99a (0.95 to 1.03) | 0.68 | 0.78 |
| Serum ferritin (ng/ml)a | 1162 (913, 1421) | 1155 (938, 1515) | 1146 (947, 1470) | 1.01 (1.00 to 1.02) | 0.25 | 1222 (904, 1528) | 1171 (967, 1513) | 1175 (966, 1536) | 1.00 (0.99 to 1.01) | 0.98 | 0.38 |
| TSat (%) | 30.4±10.7 | 30.7±8.7 | 30.4±8.9 | −0.02 (–0.32 to 0.28) | 0.90 | 30.5±10.4 | 30.5±9.1 | 30.1±10.9 | −0.07(–0.37 to 0.23) | 0.65 | 0.79 |
| iPTH (pg/ml)a | 439 (246, 618) | 420 (240, 533) | 415 (278, 591) | 1.01 (0.99 to 1.02) | 0.63 | 425 (251, 558) | 454 (296, 651) | 483 (323, 657) | 1.01a (0.99 to 1.03) | 0.25 | 0.60 |
| Calcium (mg/dl) | 9.0±0.7 | 9.0±0.8 | 9.0±0.8 | 0.00 (–0.02 to 0.02) | 0.87 | 9.1±1.0 | 9.1±0.7 | 9.0±0.7 | −0.01 (–0.03 to 0.01) | 0.41 | 0.61 |
| Phosphorus (mg/dl) | 5.2±1.3 | 5.2±1.4 | 5.3±1.3 | 0.02 (–0.02 to 0.05) | 0.41 | 5.3±1.3 | 5.2±1.4 | 5.2±1.3 | −0.02 (–0.06 to –0.02) | 0.25 | 0.13 |
| Doxercalciferol (μg/tx) | 2.55±1.66 | 2.93±1.82 | 2.86±1.73 | 0.04 (–0.06 to 0.15) | 0.41 | 2.20±1.65 | 3.23±2.29 | 3.80±2.59 | 0.21 (0.10 to 0.31) | <0.001 | 0.02 |
| Calcitriol (μg/tx) | 0.77±0.63 | 0.82±0.64 | 0.82±0.66 | 0.01 (–0.01 to 0.03) | 0.26 | 0.66±0.44 | 0.67±0.46 | 0.64±0.48 | −0.01 (–0.03 to 0.02) | 0.57 | 0.21 |
| Cinacalcet use (%) | 25 | 25 | 25 | 1.00 (0.96 to 1.04) | 0.98 | 25 | 29 | 30 | 1.04 (0.99 to 1.09) | 0.12 | 0.25 |
| Phosphate binder load (pills per day)b | 7.0±3.7 | 6.8±4.0 | 6.7±4.0 | −0.03 (–0.12 to 0.07) | 0.60 | 6.2±4.1 | 6.1±3.7 | 6.4±4.2 | −0.04 (–0.14 to 0.05) | 0.39 | 0.79 |
| hsCRP (mg/L)a | 3.8 (1.5, 12.0) | 4.4 (1.8, 14.1) | 4.4 (1.7, 10.9) | 1.01 (0.98 to 1.04) | 0.51 | 5.1 (1.8, 10.3) | 4.8 (2.2, 12.5) | 5.9 (2.0, 14.5) | 1.03a (1.00 to 1.06) | 0.02 | 0.22 |
| Systolic BP (mmHg) | 151.6±22.1 | 151.4±18.7 | 152.1±19.8 | 0.18 (–0.28 to 0.65) | 0.44 | 148.1±22.8 | 149.7±17.8 | 151.6±18.9 | 0.19 (–0.28 to 0.65) | 0.44 | 0.60 |
TSat iron saturation; tx treatment.
For non-normally distributed parameters, median and interquartile range is shown in the first three columns for each randomized group and the natural log of the variable was modeled. The interpretation is the percent change per month. For example, a β of 0.98 for log epogen is interpreted as a 2% decrease in epoetin dose per month. For the binary variable of cinacalcet, the term is expressed as the percent of participants using the agent, the slope is interpreted as a percent change in the odds of cinacalcet use over time.
The total daily dose of all phosphate binders was converted into the equivalent number of calcium acetate 667 mg pills per day according to Daugirdas et al.48 See the text for details.
The model slope is the change (95% CI) in a given parameter per month. For example a β of –0.07 for serum 25 (OH)D is interpreted as a 0.07 ng/ml decline per month in serum 25(OH)D level.
Within-group P value (the null hypothesis is that there is no change over time) and ebetween-group P value (the null hypothesis is that there is no difference between the slopes of the two arms)