Association between total volume of MSU crystal deposition and baseline characteristics
| Parameter | n | Total volume of MSU crystal depositions (cm3) (n=152) |
| Age | ||
| Spearman correlation coefficient, r* | 152 | –0.11 |
| P value* | 0.17 | |
| Age categories | ||
| <65 years | 100 | 0.07 (0.00, 19.53) |
| ≥65 years | 52 | 0.07 (0.00, 10.26) |
| P value† | 0.59 | |
| Sex | ||
| Male | 140 | 0.07 (0.00, 19.53) |
| Female | 12 | 0.07 (0.00, 0.89) |
| P value† | 0.38 | |
| Race categories | ||
| White | 98 | 0.05 (0.00, 19.53) |
| Non-white | 54 | 0.11 (0.00, 10.14) |
| P value† | 0.09 | |
| Baseline allopurinol dose category | ||
| 300 mg | 124 | 0.06 (0.00, 19.53) |
| >300 mg | 28 | 0.26 (0.00, 10.14) |
| P value† | 0.004 | |
| Duration on allopurinol (years) | ||
| Spearman correlation coefficient, r* | 152 | –0.01 |
| P value* | 0.86 | |
| Tophus status | ||
| Presence | 48 | 0.21 (0.00, 19.53) |
| Absence | 104 | 0.05 (0.00, 1.23) |
| P value† | 0.001 | |
| Number of tophi locations | ||
| None | 104 | 0.05 (0.00, 1.23) |
| 1 location only | 21 | 0.07 (0.00, 3.05) |
| 2 locations | 9 | 0.07 (0.00, 2.57) |
| >2 locations | 18 | 1.31 (0.00, 19.53) |
| P value‡ | 0.0001 | |
| Duration of gout since diagnosis (years) | ||
| Spearman correlation coefficient, r* | 152 | 0.18 |
| P value* | 0.03 | |
| Gout flares in the past 12 months | ||
| None | 70 | 0.05 (0.00, 2.57) |
| ≥1 | 82 | 0.11 (0.00, 19.53) |
| P value† | 0.01 | |
| Gout flares in the past 3 months | ||
| None | 110 | 0.05 (0.00, 10.26) |
| ≥1 | 42 | 0.11 (0.00, 19.53) |
| P value† | 0.01 | |
| Medical history of kidney stones | ||
| No | 130 | 0.07 (0.00, 19.53) |
| Yes | 22 | 0.05 (0.00, 2.50) |
| P value† | 0.32 | |
| BMI (kg/m²) | ||
| Spearman correlation coefficient, r* | 152 | 0.13 |
| P value* | 0.10 | |
| Day 1 sUA | ||
| <6.0 mg/dL | 77 | 0.03 (0.00, 4.63) |
| ≥6.0 mg/dL | 75 | 0.09 (0.00, 19.53) |
| P value† | 0.02 | |
| Renal function group§ | ||
| <90 mL/min | 115 | 0.06 (0.00, 19.53) |
| ≥90 mL/min | 35 | 0.08 (0.00, 10.14) |
| P value† | 0.49 | |
| <60 mL/min | 36 | 0.13 (0.00, 5.11) |
| ≥60 mL/min | 114 | 0.05 (0.00, 19.53) |
| P value | 0.20 | |
| C reactive protein (mg/L) | ||
| Spearman correlation coefficient, r* | 149 | 0.10 |
| P value†* | 0.24 | |
The median, minimum and maximum total volume of MSU crystal depositions are displayed for all categorical parameters.
*Estimates from Spearman correlation.
†P value from Wilcoxon Mann-Whitney test.
‡P value from Kruskal-Wallis test.
§Renal function group is estimated creatinine clearance based on the Cockcroft-Gault method.
BMI, body mass index; MSU, monosodium urate; sUA, serum urate.