CODEBOOK Chronic Kidney Disease in Children (CKID) Study: GFRCALIBRATEDSUMMARY Summary File (All the data (measurements) used for calculating U25eGFR, e2012GFR, & iGFRc) 7-30-2021 UPDATED: 30JUL2021 Start ____Field____ Section/ Column Len Format Variable Question Description Code ------ --- --------- ---------------- ------------ ------------------------------ ------------------------------ 1 6 6.0 KID Participant ID 100000= 100000 . . 699999= 699999 7 4 4.0 VISIT Visit # 0= enrollment 10= v1a 15= v1b 20= v2 30= v3 . . 90= v9 x1 or x6= Transitional (visstatus=2) 11 3 3.0 VISSTATUS Visit Status 0= Regular 1= Irregular 2= Transitional 3= Dialysis 4= Transplant 5= Phone/In-Person (PIP) Follow-up 6= Online Survey (ePIP) 9= Disenrollment 14 4 4.0 MONTH Month of the visit date 1= Janurary . . 12= December 18 4 4.0 DAY Day of the visit date 1= 1st day of the month . . 31= 31st day of the month 22 6 6.0 YEAR Year of the visit date 2004= year 2004 2021= year 2021 28 3 3.0 MALE1FE2 Participant's gender 1= Male 2= Female -9= missing 31 6 6.2 AGE Participant's age (years) 1= 1 year old . . 99= 99 years old -9= missing 37 7 7.2 WT Weight (kg), collected from PE 3.0= 3.0 . . 175.0= 175.0 -9= missing 44 6 6.1 HT Height (cm), collected from PE 60.0= 60.0 . . 230.0= 230.0 -9= missing 50 7 7.3 BSA Body Surface Area (m^2), 1.00= 1.00 Haycock formula . . 10.00= 10.00 -9= missing 57 6 6.2 SCr Serum Creatinine (mg/dL), 1.00= 1.00 from L05 (CBL) or L03 (Local) . . 10.00= 10.00 -9= missing 63 3 3.0 SCRmeth Method, source, and 1=  enzymatic/CBL/calibrated calibration status of SCr 2=   enzymatic/local/ calibrated 3=   enzymatic/local/unknown 4=   Jaffe/local 5=   unknown/local -1= NA (sCr not available) -9= missing 66 4 4.0 BUN BUN (mg/dL), from L05 (CBL) 7= 7 or L03 (Local) . . 120= 120 -9= missing 70 3 3.0 BUNLOC0CBL1 Source of BUN result 1= CBL 0= Local Lab -9= missing 73 6 6.2 CYC_IFCC Cystatin-C (mg/L), IFCC assay 1.0= 1.0 (assayed at CBL) . . 9.99= 9.99 -1= NA -9= missing 79 6 6.2 CYC_DB Cystatin-C (mg/L), Siemens 1.0= 1.0 (formerly, Dade Behring) . assay (assayed at CBL) . 9.99= 9.99 -1= NA -9= missing 85 3 3.0 KRTstatus Indicator for most recent 0= KRT-naive status of KRT 1m= On dialysis, where m indicates iteration (e.g., 11 = first dialysis) 2n= after the nth transplant and free of dialysis (e.g., 22 = second transplant) 88 7 7.2 U25eGFR estimated GFR ( ml/ 1.0= 1.0 min|1.73m^2) derived from K x . (ht/sCr) and/or K x (1/cysC) . with sex- and age- dependent 999.9= 999.9 values of K (Pierce et al., -1= NA KI, 2021) -9= missing 95 3 3.0 U25eGFRmeth Indicator for which U25eGFR 1= Average (mean) of the two equation was used single-marker sex- and age- dependent eGFR estimates 2= K x (ht/sCr), with sex- and age-dependent K 3= K x (1/cysC), with sex- and age-dependent K; cysC is IFCC calibrated -1= NA -9= missing 98 7 7.2 e2012GFR eGFR ( ml/min|1.73m^2) based 1.0= 1.0 on estimating equations (see . Schwartz et al., Kidney Int, . 2012) using Scr, BUN & 999.9= 999.9 Cystatin (CYC_DB, Siemens) -1= NA -9= missing 105 3 3.0 e2012GFRmeth Indicator for which e2012GFR 1= BUN equation was used 2= Cystatin 3= SCr 4= Cystatin & BUN 5= SCr & BUN 6= SCr & Cystatin 7= SCr, Cystatin & BUN 8= SCr, Cystatin, BUN, Sex & Height 0= SCR(updated Schwartz) -1= NA -9= missing 108 9 9.3 I Iohexol Infusion (mg) 1000.00= 1000.00 . . 9000.00= 9000.00 -1= NA -9= missing 117 6 6.1 t10 Minutes at the 1st time point 7= 7 for a 4 pt study . . 13= 13 -1= NA -9= missing 123 6 6.1 t30 Minutes at the 2nd time point 7= 7 for a 4 pt study . . 13= 13 -1= NA -9= missing 129 6 6.1 t120 Minutes at 3rd time point for 7= 7 a 4 pt study, 1st time point . for a 2 or 3 pt study . 13= 13 -1= NA -9= missing 135 6 6.1 t240 Minutes at the 2nd time point 7= 7 for a 3 pt study . . 13= 13 -1= NA -9= missing 141 6 6.1 t300 Minutes at 4th time point for 7= 7 a 4 pt study, 3rd time point . for a 3 pt study, 2nd time . point for a 2 pt study 13= 13 -1= NA -9= missing 147 8 8.4 c10 Iohexol concentration (mg/mL) 1.0= 1.0 at the 1st time point for a 4 . pt study . 999.9= 999.9 -1= NA -9= missing 155 8 8.4 c30 Iohexol concentration (mg/mL) 1.0= 1.0 at the 2nd time point for a 4 . pt study . 999.9= 999.9 -1= NA -9= missing 163 8 8.4 c120 Iohexol concentration (mg/mL) 1.0= 1.0 at 3rd time point for a 4 pt . study, 1st time point for a 2 . or 3 pt study 999.9= 999.9 -1= NA -9= missing 171 8 8.4 c240 Iohexol concentration (mg/mL) 1.0= 1.0 at the 2nd time point for a 3 . pt study . 999.9= 999.9 -1= NA -9= missing 179 8 8.4 c300 Iohexol concentration (mg/mL) 1.0= 1.0 at 4th time point for a 4 pt . study, 3rd time point for a 3 . pt study, 2nd time point for 999.9= 999.9 a 2 pt study -1= NA -9= missing 187 8 8.4 c30cv Crossvalidated iohexol 1.0= 1.0 concentration (mg/mL) at the . 2nd time point for a 4 pt . study 999.9= 999.9 -1= NA -9= missing 195 8 8.4 c120cv Crossvalidated iohexol 1.0= 1.0 concentration (mg/mL) at the . 3rd time point for a 4 pt . study 999.9= 999.9 -1= NA -9= missing 203 10 10.4 A240300 Intercept of slow curve based 1.0= 1.0 on time points at 240 & 300 . . 999.9= 999.9 -1= NA -9= missing 213 10 10.6 ALFA240300 Slope of slow curve based on 1.0= 1.0 time points at 240 & 300 . . 999.9= 999.9 -1= NA -9= missing 223 10 10.4 A120240 Intercept of slow curve based 1.0= 1.0 on time points at 120 & 240 . . 999.9= 999.9 -1= NA -9= missing 233 10 10.6 ALFA120240 Slope of slow curve based on 1.0= 1.0 time points at 120 & 240 . . 999.9= 999.9 -1= NA -9= missing 243 10 10.4 A120300 Intercept of slow curve based 1.0= 1.0 on time points at 120 & 300 . without CV . 999.9= 999.9 -1= NA -9= missing 253 10 10.6 ALFA120300 Slope of slow curve based on 1.0= 1.0 time points at 120 & 300 . without CV . 999.9= 999.9 -1= NA -9= missing 263 10 10.4 CVA120300 Intercept of slow curve based 1.0= 1.0 on time points at 120 & 300 . after CV (4 pt studies only) . 999.9= 999.9 -1= NA -9= missing 273 10 10.6 CVALFA120300 Slope of slow curve based on 1.0= 1.0 time points at 120 & 300 . after CV (4 pt studies only) . 999.9= 999.9 -1= NA -9= missing 283 10 10.4 A3PT Intercept of slow curve based 1.0= 1.0 on time points 120,240 & 300 . . 999.9= 999.9 -1= NA -9= missing 293 10 10.6 ALFA3PT Slope of slow curve based on 1.0= 1.0 time points 120,240 & 300 . . 999.9= 999.9 -1= NA -9= missing 303 10 10.4 CVB Intercept of fast curve after 1.0= 1.0 CV (4 pt studies only) . . 999.9= 999.9 -1= NA -9= missing 313 10 10.6 CVBETA Slope of fast curve after CV 1.0= 1.0 (4 pt studies only) . . 999.9= 999.9 -1= NA -9= missing 323 10 10.4 islowarea Slow area for the reported 1.0= 1.0 iGFRc (mg min/mL) . . 999.9= 999.9 9999.999= >=10000 -1= NA -9= missing 333 9 9.4 ifastarea Fast area for the reported 1.0= 1.0 iGFRc (mg min/mL) . . 999.9= 999.9 -1= NA -9= missing 342 7 7.2 islowGFR Slow part of iGFRc [I/ 1.0= 1.0 islowarea]*[1.73/bsa] (mL/ . min|1.73m^2) . 999.9= 999.9 -1= NA -9= missing 349 7 7.2 iGFRc Calibrated iohexol-based GFR 1.0= 1.0 (ml/min|1.73m^2) . . 999.9= 999.9 -1= NA -9= missing 356 4 3.0 iGFR234pts Indicator for time points/ concentrations used to 1= 240,300 calculate iGFRc 2= 120,240 3= 120,300 4= 120,240,300 5= 10,30,120,300 -1= NA -9= missing 360 3 3.0 calibrated Have the reported L07 iohexol 0= No (study date earlier concentrations been than 09nov2006 or later calibrated by the than 31mar2016) GFRcalibratedsummary.sas 1= Yes (study date is between program (i.e., divide 09nov2006 and 31mar2016) concentration by 0.89)? -1= NA (no iohexol study performed) 363 3 3.0 Caution Indicator of iGFRc caution 0= No caution 1= t30>100 mins OR t120<80 mins OR t300<120 mins 2= 2 or more concentrations increase overtime OR if c300 is missing 3= ifastarea <0 & islowarea >0 OR ifastarea >=50 OR islowarea <0 OR islowarea >625 OR cvbeta < cvalfa120300 4= (Infusion is missing OR extreme) AND (GFR4/2 differs from eGFR by 2x or more) 11= (I <2000 OR I >4400) AND (original GFR4/2 differs from eGFR by 1.5x or more);iGFR recalculated using I=3200 if within 6% of eGFR 12= GFR4/2 differs from eGFR by 1.5x or more 13= 1 or more of the times are missing and has an imputed time 14= I is missing and imputed as 3200 15= 1 Ht and/or Wt is used for BSA calculation 31= (c120 < c240 OR c120 is missing) AND (c300 > c240 OR c300 < c120 OR c300 is missing) 32= (c120 < c300) AND (c240 < c120 OR c240 is missing) 33= (c240 is missing) AND (c300 is missing) 41= (c120 > c240) AND (c300 is missing) 42= (c120 > c300) AND (c240 < c300 OR c240 is missing) 43= (c240 > c300) AND (c120 < c300 OR c120 is missing 51= concentrations derived from revised calibration method (Oct 2014-Feb 2015) yielding +18% bias -1= NA -9= missing 366 7 7.2 muiGFRc Make-up calibrated iohexol- 1.0= 1.0 based GFR (ml/min|1.73m^2) . . 999.9= 999.9 -1= NA -9= missing 373 3 3.0 muCaution Make-up iGFRc caution Identical caution codes as for the variable "caution", above. n.b., mucaution does not carry the value "51". All other values are plausible. 376 10 9.3 mudate Make-up iGFRc visit date 2005.000= 2005.000 (xxxx.yyy) . . 2018.583= 2018.583 386 6 $ VERSION Version number of data V01.01= Version 01, in Visit 01. . . V99.03= Version 03, in Visit 99.