Table 1.
Best fit parameters to equation 1 (UT = (1 – D/(ID50 + D)) × (UP – UR) + UR) relating the plasma urate concentrations of during treatment (UT) to the plasma concentrations pre-treatment (UP) and the daily dose of allopurinol (D)
| Group (n. patients, n. plasma samples) | UR (95% CI) mmol l−1 | ID50 (95% CI) mg allopurinol daily | Statistical parameters (r2, OFV) |
|---|---|---|---|
| All data (46, 112) | 0.20 (0.14, 0.25) | 226 (170, 303) | 0.738, 0.388 |
| All data* (46, 112) | 0* | 466 (423, 516) | 0.680, 0.474 |
| No diuretics (36, 86) | 0.14 (0.03, 0.22) | 313 (209, 480) | 0.670, 0.218 |
| Diuretics (10, 26) | 0.24 (0.04, 0.36) | 179 (95, 350) | 0.739, 0.159 |
| CLcr > 60 ml min−1 (29, 74) | 0.20 (0.11, 0.26) | 235 (152, 366) | 0.609, 0.190 |
| CLcr ≤ 60 ml min−1 (17, 38) | 0.17 (0.002, 0.27) | 240 (147, 405) | 0.782, 0.195 |
| Literature [18–22] (125, 184) | 0.20 (0.15, 0.23) | 186 (140, 241) | 0.441, 1.00 |
CI, confidence interval; CLcr, creatinine clearance; ID50, dose of allopurinol that has reduced the inhibitable urate (UP – UR) by 50%; OFV, objective function variable (residual sum of squares); r2, coefficient of determination; UR, apparent resistant plasma concentration of urate.
*
Equation 1 without the resistant urate concentration, i.e. UR is fixed at 0. It is a significantly poorer fit than with the resistant urate concentration (P < 0.001).