| n (%) | 44 (30%) | 101 (70%) | — |
| Age (years), median (range) | 65 (42 to 79) | 66 (24 to 83) | 0.670 |
| Male gender, n (%) | 42 (96%) | 79 (78%) | 0.010 |
| Disease duration (years), median (range) | 16 (0 to 44) | 9 (0 to 50) | 0.011 |
| Delay to starting allopurinol (months), median (range) | 48 (0 to 312) | — | — |
| Length of treatment (months), median (range) | 120 (1 to 480) | — | — |
| Self-reported adherence <90% | 7 (15%) | — | — |
| Serum urate (μmol/l), mean (SD) | 318 (66) | 434 (101) | <0.001 |
| Serum urate >360 μmol/l, n (%) | 10 (23%) | 75 (75%) | <0.001 |
| At least 1 attack in preceding year | 14 (32%) | 57 (57%) | 0.005 |