Table 3.
Main study outcomes
| Variable | na |
Change from baseline |
Analyses to determine impact of dietb |
|||||
|---|---|---|---|---|---|---|---|---|
| Standard | Modified | Standard | Modified | Estimatec | P value | 95% CI | ||
| Primary outcome | ||||||||
| Serum phosphate, mg/dl, mean (SD) | 38 | 34 | –0.336 (1.536) | –0.295 (1.456) | 0.133 | 0.69 | –0.537 | 0.803 |
| Secondary outcomes | ||||||||
| Total phosphorus intake, mg, mean (SD) | 30 | 30 | NA | NA | 77.5 | 0.343 | –84.7 | 239.7 |
| Phytate-bound phosphorus intake, mg, mean (SD) | 30 | 30 | NA | NA | 207.8 | < 0.001 | 130.4 | 285.2 |
| Fiber intake, g, mean (SD) | 30 | 30 | NA | NA | 4.65 | < 0.003 | 1.68 | 7.61 |
| Intact PTH, pg/ml, median (IQR)d | 35 | 31 | –3.9 (20.7) | –0.7 (25.0) | 0.995e | 0.968 | 0.780 | 1.270 |
| Exploratory endpoint | ||||||||
| C-terminal FGF23, RU/ml, median (IQR)d | 15 | 12 | –50 (4065) | –105 (2570) | 0.98e | 0.912 | 0.681 | 1.141 |
| Safety endpoints | ||||||||
| Serum potassium, mEq/l, mean (SD) | 39 | 34 | 0.08 (0.60) | 0.01 (0.69) | –0.097 | 0.422 | –0.335 | 0.142 |
CI, confidence interval; FGF fibroblast growth factor; IQR, interquartile range; NA, not applicable; PTH, parathyroid hormone.
Number of complete data points available for analysis.
Serum phosphate and serum potassium were described by multiple linear regression of endpoint explained by covariates of baseline and diet. Intact PTH and FGF23 were described by multiple linear regression of log(endpoint) explained by covariates of log(baseline) and diet. Total phosphorus intake, phytate-bound intake, and fiber intake were described by simple linear regression of intake explained by diet.
The standard diet was set as the reference level for all linear models.
The variables intact PTH and FGF23 are displayed nonparametric distributions.
For log−log transformations, the estimated effect of a change in diet, from standard to modified, is to change intact PTH by a factor of 0.995 and FGF23 by a factor of 0.98, respectively.