Table 2.

Characteristics of children with and without CKD in WA, 1987–2008

CharacteristicsCases (n=1994; %)Controls (n=20,032; %)P Value
Age at diagnosis of study definition of CKDa (yr)N/A
 <11639 (82.2)N/Ab
 1–5202 (10.1)N/Ab
 6–1081 (4.1)N/Ab
 11–2072 (3.6)N/Ab
Sex<0.001
 Boy1291 (64.7)10,287 (51.4)
 Girl703 (35.3)9745 (48.7)
Birth weight (g)<0.001
 400–2499241 (12.1)1105 (5.5)
 2500–39991466 (73.5)16,217 (81.0)
 ≥4000277 (13.9)2608 (13.0)
 Missing10 (0.5)102 (0.5)
Gestational length (wk)<0.001
 <37294 (14.7)1586 (7.9)
 37–421236 (62.0)13,602 (67.9)
 >42139 (7.0)1913 (9.6)
 Missing325 (16.3)2931 (14.6)
Multiple births0.12
 Singleton1930 (96.8)19,495 (97.3)
 Multiple64 (3.2)524 (2.6)
 Missing0 (0)13 (0.1)
  • N/A, not applicable.

  • a CKD cases were defined using hospital discharge ICD-9 codes for renal dysplasia/aplasia (753.0 and 753.15) and obstructive uropathy (599.6 and 753.2).

  • b Controls were matched to cases by year of birth.