Table 2.

Effect of Allopurinol on Primary and Secondary Outcomes.^*

Outcome	Placebo (N = 263)	Allopurinol (N = 267)	Allopurinol Effect (95% CI)†
Primary outcome
Baseline-adjusted iohexol-based GFR at end of the 2-mo washout period (95% CI) — ml/min/1.73 m2	61.2 (58.1 to 64.2)	61.2 (58.1 to 64.2)	0.001 (−1.9 to 1.9)‡
Secondary outcomes
Baseline-adjusted iohexol-based GFR at end of the intervention period (95% CI) — ml/min/1.73 m2	61.0 (57.9 to 64.0)	61.3 (58.3 to 64.3)	0.3 (−1.7 to 2.3)
Baseline-adjusted estimated GFR at 4 mo after randomization (95% CI) — ml/min/1.73 m2	70.0 (67.1 to 72.9)	70.3 (67.3 to 73.3)	0.3 (−1.6 to 2.2)
Slope of GFR (95% CI) — ml/min/1.73 m2/yr
Iohexol-based	−2.5 (−3.1 to −1.8)	−3.0 (−3.7 to −2.3)	−0.6 (−1.5 to 0.4)
Estimated	−2.1 (−2.6 to −1.6)	−2.4 (−2.9 to −1.8)	−0.3 (−1.0 to 0.5)
Urinary albumin excretion rate (95% CI) — μg/min
At end of the washout period	31.7 (19.5 to 51.6)	42.9 (24.7 to 74.4)	1.4 (1.0 to 1.8)
At end of the intervention period	37.4 (25.3 to 55.5)	47.9 (32.5 to 70.6)	1.3 (1.0 to 1.6)
Serum creatinine doubling or progression to end-stage kidney disease — no. (%)§	11 (4.2)	13 (4.9)	1.2 (0.5 to 2.9)
Fatal or nonfatal cardiovascular event — no. (%)	9 (3.4)	15 (5.6)	1.9 (0.8 to 4.5)

^*Data for continuous outcomes are adjusted means, except for outcomes involving the urinary albumin excretion rate, for which they are adjusted geometric means.

^†For GFR outcomes, the allopurinol effect is the estimated difference between the allopurinol group and the placebo group; for urinary albumin excretion rate outcomes, it is the ratio between the allopurinol group and the placebo group; and for the time-to-event analyses of serum creatinine doubling or progression to end-stage kidney disease and of fatal or nonfatal cardiovascular events, it is the hazard ratio for the events with allopurinol as compared with placebo.

^‡P = 0.99.

^§Two patients in the placebo group and six in the allopurinol group had progression to end-stage kidney disease.