Table 1.

Baseline characteristics of adults ages 18–54 years old initiating dialysis in the United States stratified by period of dialysis initiation

CovariatesYear of Dialysis InitiationAbsolute Standardized Difference,a 1996–2001 versus 2008–2013
1996–2001, n=145,7972002–2007, n=165,0652008–2013, n=169,735
Patient demographic and socioeconomic characteristics
 Age group, %
  18–289880.05
  29–382018170.08
  39–483837370.02
  49–543336380.12
 Women, %4241400.05
 Race, %
  White5353550.05
  Black4141380.05
  Others6660.00
 Hispanic ethnicity, %1315170.12
 Disability, %1818220.11
 Household income ($1000), mean (SD)49.2 (13)49.2 (12)49.2 (12)0.00
Patient health characteristics
 Modality, %
  In-center hemodialysis8690890.09
  Home dialysis149110.09
 Diabetes, %4145500.17
 Coronary heart disease, %111080.10
 Cancer, %2230.04
 Heart failure, %1819190.02
 Lung disease, %3340.08
 Cerebrovascular disease, %4550.04
 Peripheral vascular disease, %7770.01
 Smokes, %89100.06
 Drug or alcohol abuse, %5550.02
 Immobility, %2340.08
 Hemoglobin, g/dl, mean (SD)b9.6 (2)9.9 (2)9.6 (2)0.02
 Serum albumin, g/dl, mean (SD)b3.1 (1)3.1 (1)3.1 (1)0.03
 Body mass index, kg/m2, mean (SD)b27.5 (8)29.3 (8)30.7 (9)0.39
 eGFR, ml/min per 1.73 m2, mean (SD)b6.8 (5)8.3 (6)9.4 (6)0.46
County unemployment rate, mean % (SD)5 (2)5 (2)9 (3)1.45
  • a Standardized difference is the difference in means (or proportions) across comparison groups as a proportion of the pooled SD. A standardized difference of ≥0.1 suggests a meaningful difference in a characteristic across the two time periods being compared. Household income is the median income in a patient’s zip code.

  • b Hemoglobin has 10% missing (48,711 patients), serum albumin has 25% missing (120,879 patients), and body mass index has 3% missing (14,611 patients). eGFR is calculated from the Chronic Kidney Disease Epidemiology Collaboration equation and has <1% missing (2449 patients); 31% of patients in the cohort have at least one missing value for either hemoglobin, serum albumin, body mass index, or eGFR.