Table 2.
Characteristics of patients in the cohort
| Characteristic | Cohort 1 n = 241 | Cohort 2 n = 194 | Cohort 3 n = 21 | Total N = 456 |
|---|---|---|---|---|
| Visiting age (yr), median (IQR) | 2.1 (1.5–7.1) | 2.0 (1.0–5.0) | 2.2 (1.1–3.0) | 2.1 (1.2–6.1) |
| Minority individual, n (%) | 22 (9%) | 5 (3%) | 2 (10%) | 29 (6%) |
| Sex, male, n (%) | 170 (71%) | 127 (65%) | 15 (71%) | 312 (68%) |
| BMI (kg/m2), median (IQR) | 16.2 (14.9–18.4) | 15.9 (14.8–17.4) | 18.0 (15.7–19.4) | 15.8 (14.9–18.0) |
| eGFR (ml/min per 1.73 m2), median (IQR) | 124.8 (118.4–165.0) | 156.0 (136.0–182.3) | 140.0 (101.8–158.4) | 130.4 (122.6–174.2) |
| Family history, n (%) | 70 (29%) | 30 (15%) | 4 (19%) | 104 (23%) |
| Symptomatic episode history, n (%) | 88 (37%) | 82 (42%) | 3 (14%) | 173 (38%) |
| Nephrocalcinosis, n (%) | 12 (5%) | 15 (8%) | 0 (0%) | 27 (6%) |
| Recurrent stone, n (%) | 35 (15%) | 17 (9%) | 3 (14%) | 55 (12%) |
| Bilateral stone, n (%) | 76 (32%) | 61 (31%) | 7 (33%) | 144 (32%) |
| Multiple stone, n (%) | 122 (51%) | 80 (41%) | 11 (52%) | 213 (47%) |
| Stone burden in diameter (cm), median (IQR) | 2.0 (1.0–2.8) | 1.5 (0.9–1.9) | 1.5 (1.0–2.0) | 1.5 (1.0–2.1) |
| Serum uric acid (μmol/l), median (IQR) | 287 (247–331) | 252 (205–316) | 279 (266–308) | 266 (223–324) |
| Serum calcium (mmol/l), median (IQR) | 2.5 (2.4–2.5) | 2.4 (2.4–2.5) | 2.5 (2.4–2.6) | 2.5 (2.4–2.5) |
| Serum phosphate (mmol/l), median (IQR) | 1.7 (1.6–1.8) | 1.7 (1.5–1.8) | 1.7 (1.6–1.8) | 1.7 (1.5–1.8) |
| Serum magnesium (mmol/l), median (IQR) | 0.9 (0.8–0.9) | 0.9 (0.9–1.0) | 0.9 (0.9–1.0) | 0.9 (0.9–1.0) |
| Stone composition, n (%) | ||||
| Calcium oxalate | 142 (70%) | 72 (60%) | 16 (80%) | 230 (67%) |
| Cystine | 22 (11%) | 18 (15%) | 1 (5%) | 41 (12%) |
| Carbonate apatite | 17 (8%) | 17 (14%) | 1 (5%) | 35 (10%) |
| Brushite | 11 (5%) | 6 (5%) | 1 (5%) | 18 (5%) |
| Octacalcium phosphate | 0 (0%) | 1 (1%) | 0 (0%) | 1 (1%) |
| Xanthine | 0 (0%) | 1 (1%) | 0 (0%) | 1 (1%) |
| 2,8-dihydroxyadenine | 1 (1%) | 0 (0%) | 0 (0%) | 1 (1%) |
| Magnesium ammonium phosphate | 4 (2%) | 1 (1%) | 1 (5%) | 6 (2%) |
| Uric acid | 6 (3%) | 3 (3%) | 0 (0%) | 9 (3%) |
| Ammonium urate | 1 (1%) | 1 (1%) | 0 (0%) | 2 (1%) |
BMI, body mass index; eGFR, estimated glomerular filtration rate; IQR, interquartile range.