Table 1.

Baseline characteristics of patients discharged home from the emergency department (ED) with AKI

CharacteristicPatients Discharged Home from the ED with AKI, n (%)a
All PatientsAKI Stageb
123
Cohort size6346601229044
Age, yr, mean (SD)69 (13)69 (13)68 (14)65 (13)‡§
 40 to <652326 (37)2189 (36)112 (39)25 (57)‡§
 65 to <802475 (39)2351 (39)114 (39)10 (23)‡§
 ≥801545 (24)1472 (25)64 (22)9 (21)
Women2948 (47)2745 (46)177 (61)26 (59)
Year of cohort entry (index date)
 2003–20051593 (25)1497 (25)87 (30)9 (21)‡§
 2006–20082903 (46)2769 (46)116 (40)18 (41)
 2009–20111850 (29)1746 (29)87 (30)17 (39)‡§
Rural residence969 (15)912 (15)51 (18)6 (14)§
Comorbid conditionsc
 Hypertension4783 (75)4525 (75)222 (77)36 (82)‡§
 Diabetes2405 (38)2292 (38)100 (35)13 (30)‡§
 Heart failureNot reported1325 (22)48 (17)≤5 (≤11)‡§
 Coronary artery diseased2160 (34)2069 (34)78 (27)13 (30)
 Chronic liver diseaseNot reported399 (7)24 (8)≤5 (≤11)§
 NephrolithiasisNot reported162 (3)11(4)≤5 (≤11)‡§
Aggregated diagnosis group point scoree
 0–51756 (28)1669 (28)79 (27)9 (21)‡§
 ≥64589 (72)4343 (72)211 (73)35 (80)‡§
Medication utilizationf
 Ontario Drug Benefit eligible patients4605 (73)4367 (73)213 (73)25 (57)‡§
Medication classg
 Angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers2750/4605 (60)2614/4367 (60)122/213 (57)14/25 (56)
 Antibiotics2041/4605 (44)1931/4367 (44)97/213 (46)13/25 (52)‡§
 Antipsychotic medicationsNot reported284/4367 (7)18/213 (9)≤5/25 (≤20)
 Nonpotassium-sparing diuretics2609/4605 (57)2465/4367 (56)128/213 (60)16/25 (64)
 Potassium-sparing diureticsNot reported511/4367 (12)34/213 (16)≤5/25 (≤20)‡§
 Nonsteroidal anti-inflammatory drugsh892/4605 (19)849/4367 (19)34/213 (16)9/25 (36)‡§
 No. of unique drug names, median (interquartile range)5 (0–10)5 (0–10)5 (0–10)0 (0–7)
Pre-ED baseline kidney functioni
 Baseline serum creatinine in mg/dl, mean (SD)1.1 (0.6)1.2 (0.6)0.9 (0.3)1.1 (1.0)§
  No. of d taken before ED visit, mean (SD)133 (102)132 (102)140 (105)152 (116)‡§
  No. with serum creatinine ≤0.6 mg/dlNot reported215 (4)44 (15)≤5 (≤11)‡§
 Baseline eGFR, ml/min per 1.73 m2
  ≥603919 (62)3654 (61)230 (80)35 (80)
  45 to <60Not reported1029 (17)34 (12)≤5 (≤11)‡§
  30 to <45Not reported833 (14)19 (7)≤5 (≤11)
  <30Not reported496 (8)7 (2)≤5 (≤11)§
 Albumin-to-creatinine ratio, mg/g1689 (27)1602 (27)77 (27)10 (23)
  <30Not reported959 (16)49 (17)≤5 (≤11)‡§
  30 to <300Not reported262 (4)13 (5)≤5 (≤11)
  ≥300Not reported381 (6)15 (5)≤5 (≤11)
ED visit laboratory values
 Serum potassium in mEq/L, mean (SD)4.2 (0.6)4.2 (0.6)4.1 (0.8)4.2 (0.8)§
 Serum sodium in mEq/L, mean (SD)137 (5)137 (5)136 (5)134 (5)‡§
 Serum creatinine in mg/dl
  Mean (SD)1.7 (0.8)1.6 (0.7)2.0 (0.8)3.8 (2.1)‡§
  Median (interquartile range)1.5 (1.2–1.8)1.4 (1.2–1.8)1.8 (1.4–2.3)3.4 (2.3–4.8)
 Absolute change in serum creatinine in mg/dl
  Mean (SD)0.5 (0.4)0.5 (0.2)1.1 (0.5)2.7 (1.4)‡§
  Median (interquartile range)0.4 (0.4–0.6)0.4 (0.4–0.5)1.0 (0.8–1.3)2.5 (1.6–3.7)
 Percent change in serum creatinine, %
  Mean (SD)52 (34)48 (18)129 (26)294 (128)‡§
  Median (interquartile range)45 (35–60)44 (34–57)121 (108–144)265 (224–359)
Previous health care utilizationj
 ED visit in the previous 30 d1114 (18)1062 (18)45 (16)7 (16)
 Hospitalization in the previous 30 d481 (8)451 (8)24 (8)6 (14)‡§
 Family physician visit6251 (99)5924 (99)283 (98)44 (71)‡§
 General internist visit1470 (23)1385 (23)76 (26)9 (21)§
 Nephrology visitNot reported270 (5)14 (5)≤5 (≤11)
 Urology visit1132 (18)1084 (18)40 (14)8 (18)§
 Imaging and investigations
  Computed tomography with contrastNot reported175 (3)7 (2)≤5 (≤11)
  Coronary angiogram or revascularizationNot reported138 (2)6 (2)≤5 (≤11)‡§
ED patient acuity and wait times
 Canadian triage acuity scalek
  1 and 21321 (21)1271 (21)43 (15)7 (16)
  33797 (60)3579 (60)193 (67)25 (57)§
  4 and 51228 (19)1162 (19)54 (19)12 (27)‡§
 Time (in hr) waiting for physician assessment, mean (SD)
  Canadian triage acuity scale 1 and 20.6 (0.8)0.6 (0.8)0.5 (0.6)0.3 (0.5)‡§
  Canadian triage acuity scale 31.3 (1.3)1.3 (1.3)1.5 (1.3)1.6 (1.1)‡§
  Canadian triage acuity scale 4 and 51.6 (1.4)1.6 (1.4)1.7 (1.4)1.4 (1.2)‡§
  • A standardized difference of ≥10% was found between the following two AKI subgroup comparisons: stage 1 versus stage 2; stage 1 versus stage 3; and §stage 2 versus stage 3. To convert serum creatinine from traditional units (milligram per deciliter) to SI units (micromole), multiply by 88.42.

  • a Reported as n (%) unless otherwise noted. To comply with privacy regulations for minimizing the chance of patient reidentification, numbers of patients were suppressed in five or fewer patients. The total number of patients was not reported if there were other calculations that could result in the reidentification of five or fewer patients.

  • b Stage 1, evidence of a relative increase in serum creatinine value of ≥50% to <100% or ≥0.3 mg/dl from baseline; stage 2, evidence of a relative increase in serum creatinine value of ≥100% to <200% from baseline; and stage 3, evidence of a relative increase in serum creatinine value of >200% from baseline or an absolute increase in serum creatinine value to ≥4 mg/dl or the initiation of dialysis.

  • c Look-back window for comorbidities was 5 years unless otherwise noted.

  • d Does not include angina.

  • e The Aggregated Diagnosis Groups point score, derived from the John Hopkins Adjusted Clinical Groups system, is a weighted measure of health care utilization as a proxy measure for comorbidity and accounts for the duration of condition, severity of condition, diagnostic certainty, etiology of the condition, and specialty care involvement. The higher Aggregated Diagnosis Groups score, the greater the comorbidity. Individuals with an Aggregated Diagnosis Groups score of 0–2 reflect low health care costs with no prior hospitalizations; 3–5 reflects high health care costs but no prior hospitalizations; and a score of ≥6 reflects high health care costs and at least one prior hospitalization.

  • f Look-back window for medication utilization was 120 days.

  • g Percentages reported are on the basis of the number of Ontario Drug Benefit eligible patients (those aged ≥65 years).

  • h Does not include acetylsalicylic acid.

  • i Pre-ED visit look-back window was 7–365 days.

  • j Look-back window for health care utilization was 365 days unless otherwise noted.

  • k Patients with a Canadian Triage Acuity Scale score of 1 or 2 need to be seen immediately 98% of the time or within 15 minutes 95% of the time, respectively. Patients with a Canadian Triage Acuity Scale score of 3 need to be seen within 30 minutes 90% of the time or 60 minutes 85% of the time, respectively. Patients with a Canadian Triage Acuity Scale score of 4 or 5 need to be seen within 120 minutes 80% of the time.