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Table 2 Primary and secondary efficacy endpoints

From: The effect of kidney function on the urate lowering effect and safety of increasing allopurinol above doses based on creatinine clearance: a post hoc analysis of a randomized controlled trial

Variable C/DE (n = 93) DE/DE (n = 90) P valuesa
CrCL <30 ml/min (n = 14) CrCL ≥30 to <60 ml/min (n = 31) CrCL ≥60 ml/min (n = 48) CrCL <30 ml/min (n = 10) CrCL ≥30 to<60 ml/min (n = 40) CrCL ≥60 ml/min (n = 40)  
Change in serum urate (mg/dl), mean (SE)
 Baseline to month 12 -0.67 (0.67) -0.05 (0.33) -0.25 (0.26) -1.49 (0.47) -2.27 (0.29) -1.06 (0.24) 0.04
 Baseline to month 24 -2.23 (0.88) -1.41 (0.36) -1.10 (0.25) -2.47 (0.68) -2.35 (0.28) -0.86 (0.27) 0.15
 Month 12 to month 24 -1.42 (0.45) -1.51 (0.41) -0.87 (0.25) -1.20 (0.29) 0.01 (0.17) 0.34 (0.23) 0.82
Serum urate <6 mg/dl, %
 Month 12 13% 25% 49% 57% 86% 86% 0.50
 Month 24 57% 68% 72% 71% 82% 79% 0.93
Mean (SE) serum urate
 Baseline 8.25 (0.41) 7.10 (0.29) 6.82 (0.21) 8.02 (0.46) 7.63 (0.26) 6.52 (0.20) <0.001b
 Month 12 7.38 (0.57) 7.13 (0.32) 6.37 (0.24) 5.91 (0.59) 5.25 (0.12) 5.34 (0.19) 0.20
 Month 24 5.93 (0.71) 5.72 (0.25) 5.62 (0.19) 5.21 (0.30) 5.27 (0.18) 5.61 (0.25) 0.46
Percentage change in serum urate from baseline, mean (SE)
 Baseline to month 12 -6.2 (7.2) 1.6 (4.9) -1.9 (3.4) -20.2 (6.0) -27.5 (2.9) -15.0 (3.5) 0.08
 Baseline to month 24 -25.5 (8.5) -16.6 (4.8) -13.9 (3.2) -30.0 (5.8) -29.1 (2.8) -11.8 (4.1) 0.14
 Month 12 to month 24 -19.4 (5.4) -17.9 (4.6) -10.1 (3.5) -2.4 (5.4) 0.87 (3.2) 7.75 (4.6) 0.99
Percentage with at least one flare in preceding month
 Baseline 50% 38.7% 56.3% 40.0% 32.5% 42.5% 0.17b
 Month 12 37.5% 12.5% 39% 14.3% 34.3% 32.1% 0.10
 Month 24 14.3% 13.6% 20.5% 0.0% 15.2% 3.4% 0.30
Allopurinol dose (mg/day) to achieve target SU at month 24, mean (range) 262.5 (150–500) 389.3 (250–650) 439.3 (300–800) 350.0 (250–600) 396.3 (200–700) 491.3 (300–900) 0.002b
Number of participants requiring >300 mg/day to achieve target SU at month 24 1/4 (25%) 9/14 (64.3%) 20/28 (71.4%) 1/5 (20%) 16/27 (59.3%) 19/23 (82.6%) 0.013
Percentage of individuals receiving anti-inflammatory prophylaxis
 Baseline 35.7% 48.4% 52.1% 40.0% 60.0% 57.5% 0.30b
 Month 12 37.5% 29.2% 29.3% 71.4% 34.3% 14.3% 0.15
 Month 24 14.3% 18.2% 15.4% 57.1% 9.1% 10.3% 0.16
HAQ mean (SE) change
 Baseline to month 12 -0.10 (0.19) 0.10 (0.15) -0.14 (0.09) 0.47 (0.28) 0.06 (0.12) -0.13 (0.11) 0.25
 Baseline to month 24 -0.09 (0.21) 0.14 (0.11) -0.32 (0.07) -0.19 (0.30) -0.05 (0.11) -0.20 (0.12) 0.67
 Month 12 to month 24 0.10 (0.04) -0.09 (0.18) -0.22 (0.08) -0.72 (0.35) -0.05 (0.13) -0.05 (0.11) 0.04
Pain VAS mean (SE) change
 Baseline to month 12 -0.25 (0.90) 1.04 (0.51) -0.02 (0.40) 0.43 (0.61) 0.17 (0.40) -0.43 (0.54) 0.57
 Baseline to month 24 -1.15 (1.3) 0.27 (0.62) -1.10 (0.35) -0.50 (1.36) -0.64 (0.37) -1.28 (0.53) 0.56
 Month 12 to month 24 -0.71 (0.71) -0.52 (0.84) -1.03 (0.37) -0.60 (0.87) -0.67 (0.34) -0.78 (0.57) 0.93
SJC mean (SE) change
 Baseline to month 12 -2.88 (1.84) -0.04 (1.05) -0.07 (0.72) 0.86 (1.6) -1.17 (0.89) 0.17 (0.53) 0.19
 Baseline to month 24 -2.14 (1.39) -2.86 (1.65) -1.26 (0.73) -0.67 (0.67) -1.85 (0.93) -0.24 (0.27) 0.99
 Month 12 to month 24 1.23 (1.16) -2.91 (2.24) -1.34 (0.98) 0 (0) -0.52 (0.42) -0.37 (0.59) 0.57
TJC mean (SE) change
 Baseline to month 12 2.13 (3.56) 0.04 (1.33) -2.83 (1.07) -0.57 (0.62) -1.57 (0.90) 1.18 (1.42) 0.04
 Baseline to month 24 -2.57 (1.97) -1.73 (1.49) -2.08 (0.88) -0.50 (0.34) -0.42 (1.54) -0.97 (0.50) 0.97
 Month 12 to month 24 -5.0 (3.0) -2.57 (1.83) 0.65 (0.55) -0.20 (0.20) 1.18 (1.32) -1.96 (1.37) 0.02
  1. C/DE control/dose escalation phasegroup, DD immediate dose escalation group, CrCL creatinine clearance, SU serum urate, HAQ health assessment questionnaire, VAS visual analogue scale, SJC swollen joint count, TJC tender joint count
  2. aFor levels and changes after baseline the p value tests the significance of randomization depending on baseline CrCL
  3. bFor baseline assessments the p value represents the significance of differences between kidney function groups