Table 1.

Characteristics of the 2239 first-time symptomatic stone formers in Olmsted County, Minnesota (1984–2003), with and without symptomatic recurrence

CharacteristicSymptomatic RecurrenceP Valuea
No (n=1532)Yes (n=707)
Clinical
 Age (yr)42 (32, 54)41 (31, 51.0)0.03
 Men937 (61)462 (65)0.06
 White race1313 (86)659 (93)<0.001
 Family history332 (22)243 (34)<0.001
 BMI at nephrolithiasis diagnosis (kg/m2)27 (24, 31)28 (24, 31)0.38
 Patient pregnant during the episode34 (2.2)23 (3.3)0.15
 Cigarette smoking status0.50
  Current338 (22)170 (24)
  Former340 (22)146 (21)
  Never854 (56)391 (55)
 Prior incidental (asymptomatic) stone on imaging73 (4.8)51 (7.2)0.02
 Prior suspected stoneb70 (4.6)83 (12)<0.001
 Pain0.27
  Renal colic1384 (90)644 (91)
  Atypical101 (6.6)36 (5.1)
  None47 (3.1)27 (3.8)
 Temperature>38°C100 (6.5)44 (6.2)0.78
 Urinary tract infection79 (5.2)33 (4.7)0.62
 Microscopic hematuria1203 (79)547 (77)0.54
 Gross hematuria304 (20)175 (25)<0.01
Imaging
 Stone number<0.001
  Missing: no imaging10249
  0233 (16)77 (12)
  1825 (58)288 (44)
  ≥2372 (26)293 (45)
 Any nonobstructing stone404 (28)277 (42)<0.001
 Any obstructing stone1083 (76)505 (77)0.61
 Staghorn stone19 (1.3)4 (0.6)0.14
 Symptomatic pelvic or lower-pole stone124 (8.7)145 (22)<0.001
 Ureteropelvic junction stone76 (5.3)41 (6.2)0.40
 Ureter stone501 (35)242 (37)0.44
 Ureterovesicular junction stone467 (33)176 (27)<0.01
 Largest stone diameter0.03
  <3 mm or reported as “tiny” or not reported957 (62)471 (66)
  3–6 mm438 (29)164 (23)
  >6 mm137 (8.9)72 (10)
Stone analysis
 Composition groups0.04
  Unknown745353
  Mostly oxalate608 (77)256 (72)
  Mostly apatite132 (17)57 (16)
  Any brushite6 (0.8)4 (1.1)
  Any struvite7 (0.9)5 (1.4)
  Any uric acid26 (3.3)29 (8.1)
  Any calcium carbonate2 (0.3)1 (0.3)
  Any urate2 (0.3)0 (0.0)
  Any drug4 (0.5)2 (0.6)
Comorbidities
 CKD60 (3.9)21 (3.0)0.27
 Hypertension385 (25)167 (24)0.44
 Diabetes mellitus74 (4.8)38 (5.4)0.58
 Dyslipidemia244 (16)108 (15)0.69
 Gout41 (2.7)15 (2.1)0.43
 Hyperparathyroidism5 (0.3)3 (0.4)0.72
 Diarrhea145 (9.5)67 (9.5)0.99
 Lower urinary tract symptoms549 (36)236 (33)0.26
Treatments
 Stone surgery501 (33)214 (30)0.25
 Documented diet alteration272 (18)151 (21)0.04
 Stone clinic evaluation146 (9.5)94 (13)<0.01
 Stone prevention medications42 (2.7)27 (3.8)0.17
  • Values are expressed as number (percentage) of patients or median (25th, 75th percentiles). BMI, body mass index.

  • a From chi-squared or rank-sum test.

  • b Characteristic renal colic attributed to a stone but no stone seen on imaging or voided.