Table 1

Baseline characteristics

VariablesPrematchedMatched
Non-AKI (N = 221,518)AKI (N = 73,761)Standardized differencesNon-AKI (N = 65,151)AKI (N = 65,151)Standardized differences
Demographics
 Age, mean (SD)65.67 (11.06)67.69 (11.06)0.183*67.29 (11.06)67.49 (11.12)0.018*
 Female, n (%)6,935 (3.1)1,657 (2.2)0.055*1,516 (2.3)1,511 (2.3)0.001
 Race, n (%)
  Unknown7,283 (3.3)2,460 (3.3)0.0032,170 (3.3)2,037 (3.1)0.012*
  African American44,264 (20.0)16,419 (22.3)0.056*14,464 (22.2)14,572 (22.4)0.004
  Other5,142 (2.3)1,676 (2.3)0.0031,488 (2.3)1,496 (2.3)0.001
  White164,829 (74.4)53,206 (72.1)0.051*47,029 (72.2)47,046 (72.2)0.001
Preadmission outpatient medications, n (%)
 Diuretics102,538 (46.3)43,521 (59.0)0.257*37,446 (57.5)37,475 (57.5)0.001
 RAAS inhibitors156,113 (70.5)55,813 (75.7)0.117*49,187 (75.5)49,040 (75.3)0.005
 Aminoglycosides2,406 (1.1)916 (1.2)0.015*807 (1.2)788 (1.2)0.003
 NSAIDs20,264 (9.1)4,759 (6.5)0.101*4,491 (6.9)4,484 (6.9)<0.001
 Indomethacin2,068 (0.9)759 (1.0)0.010*711 (1.1)675 (1.0)0.005
 Quinine1,213 (0.5)478 (0.6)0.013*423 (0.6)437 (0.7)0.003
Preadmission laboratory/vitals
 HbA1c, %, mean (SD)7.62 (1.74)7.65 (1.80)0.021*7.70 (1.81)7.64 (1.78)0.032*
 HbA1c, mmol/mol, mean59.7960.1160.7060.00
 HbA1c nonmissing, n (%)157,367 (71.0)52,880 (71.7)0.014*46,466 (71.3)46,590 (71.5)0.004
 eGFR, mean (SD)72.90 (21.91)63.71 (23.30)0.406*65.32 (23.08)65.17 (23.08)0.007
 SBP, mean (SD)134.00 (14.11)136.05 (15.54)0.138*135.72 (15.40)135.79 (15.31)0.005
 Mean SBP nonmissing, n (%)221,107 (99.8)73,601 (99.8)0.00765,012 (99.8)65,007 (99.8)0.002
 Glucose measurements prior year, mean (SD)5.41 (12.10)5.93 (14.59)0.039*5.86 (14.41)5.81 (14.03)0.003
 History of hypoglycemia, n (%)15,286 (6.9)6,913 (9.4)0.09*5,987 (9.2)5,814 (8.9)0.009
Preadmission chronic conditions/utilization
 No. of encounters (1 year), mean (SD)33.25 (25.98)32.53 (25.57)0.028*32.79 (25.82)32.58 (25.64)0.008
 CKD, n (%)17,630 (8.0)11,895 (16.1)0.253*9,263 (14.2)9,341 (14.3)0.003
 Heart failure, n (%)33,428 (15.1)16,133 (21.9)0.175*13,599 (20.9)13,685 (21.0)0.003
 Peripheral vascular disease, n (%)37,172 (16.8)13,957 (18.9)0.056*12,253 (18.8)12,168 (18.7)0.003
 Valvular heart disease, n (%)11,491 (5.2)4,478 (6.1)0.038*3,843 (5.9)3,953 (6.1)0.007
 Prior cardiac surgery, n (%)7,299 (3.3)2,380 (3.2)0.0042,160 (3.3)2,153 (3.3)0.001
 Type 2 diabetes (ICD-9), n (%)217,618 (98.2)72,483 (98.3)0.00264,066 (98.3)64,026 (98.3)0.005
 Coronary artery disease, n (%)92,155 (41.6)30,945 (42.0)0.00727,338 (42.0)27,473 (42.2)0.004
 Hypertension, n (%)190,925 (86.2)66,692 (90.4)0.132*58,533 (89.8)58,645 (90.0)0.006
 Advanced liver disease, n (%)5,737 (2.6)2,004 (2.7)0.0081,798 (2.8)1,781 (2.7)0.002
 Cancer (ICD-9), n (%)37,194 (16.8)12,996 (17.6)0.022*11,362 (17.4)11,500 (17.7)0.006
Inpatient conditions/laboratory/vitals
 Admission SBP, mean (SD)134.22 (16.81)130.45 (18.91)0.211*131.53 (18.27)131.45 (18.40)0.005
 Admission mean SBP nonmissing, n (%)216,289 (97.6)72,249 (98.0)0.021*63,797 (97.9)63,773 (97.9)0.003
 ICU stay, n (%)30,115 (13.6)13,887 (18.8)0.142*11,342 (17.4)11,491 (17.6)0.006
 Mechanical ventilation, n (%)3,823 (1.7)3,030 (4.1)0.142*1,995 (3.1)2,092 (3.2)0.009
 Sepsis, n (%)2,802 (1.3)8,487 (11.5)0.428*2,726 (4.2)3,179 (4.9)0.033*
 Acute coronary syndrome, n (%)18,616 (8.4)5,798 (7.9)0.02*4,876 (7.5)5,100 (7.8)0.013*
 Cardiac surgery, n (%)2,573 (1.2)1,361 (1.8)0.056*1,276 (2.0)1,226 (1.9)0.006
 Major vascular surgery, n (%)9,416 (4.3)6,365 (8.6)0.179*4,600 (7.1)4,666 (7.2)0.004
 Abdominal surgery, n (%)5,590 (2.5)1,863 (2.5)<0.0011,653 (2.5)1,675 (2.6)0.002
 Gastrointestinal bleed, n (%)4,570 (2.1)2,195 (3.0)0.058*1,752 (2.7)1,815 (2.8)0.006
 Advanced liver disease, n (%)5,050 (2.3)1,976 (2.7)0.026*1,718 (2.6)1,717 (2.6)<0.001
 Radiology IV contrast, n (%)10,784 (4.9)2,307 (3.1)0.089*2,200 (3.4)2,130 (3.3)0.006
 Fluoroquinolone use 48 h prior to discharge, n (%)13,221 (6.0)7,444 (10.1)0.152*5,868 (9.0)5,836 (9.0)0.002
  • NSAIDs, nonsteroidal anti-inflammatory drugs; RAAS, renin-angiotensin-aldosterone system. Standardized differences are the absolute difference in means or percentage divided by an evenly weighted pooled SD or difference between groups in number of SDs. In the PS-matched cohort, all standardized differences were <10% (or 0.1), indicating good balance.

  • *P < 0.05.