Participant characteristics at the time of acute kidney injury by estimated acute interstitial nephritis status
| Variables | Estimated acute interstitial nephritis (eAIN; n=34) | Not eAIN (n=321) | P value |
| Demographics and comorbidities | |||
| Age | 66.4 (57.8,75.5) | 64.6 (56.7,73.1) | 0.52 |
| Female sex | 12 (35.3%) | 158 (49.1%) | 0.13 |
| Black race | 1 (2.9%) | 20 (6.2%) | 0.44 |
| Diabetes | 10 (29.4%) | 80 (24.8%) | 0.56 |
| Hypertension | 28 (82.4%) | 217 (67.4%) | 0.07 |
| Cirrhosis | 0 (0%) | 7 (2.2%) | 0.39 |
| Chronic kidney disease | 7 (20.6%) | 42 (13%) | 0.22 |
| Cancer and stage | |||
| Lung | 9 (26.5%) | 102 (31.7%) | 0.53 |
| Melanoma | 5 (14.7%) | 46 (14.3%) | 0.95 |
| Kidney | 10 (29.4%) | 57 (17.7%) | 0.10 |
| Digestive | 1 (2.9%) | 34 (10.6%) | 0.16 |
| Head and neck | 4 (11.8%) | 18 (5.6%) | 0.16 |
| Breast | 0 (0%) | 7 (2.2%) | 0.39 |
| Other | 5 (14.7%) | 58 (18%) | 0.63 |
| Stage 4 cancer | 30 (88.2%) | 275 (85.4%) | 0.65 |
| Laboratory findings at AKI | |||
| Creatinine | 3.3 (2.1, 6.1) | 1.4 (1.2, 1.9) | <0.001 |
| Estimated glomerular filtration rate | 19.2 (9.3, 26.5) | 45.2 (31.8, 59.5) | <0.001 |
| Blood urea nitrogen (BUN) | 39 (25, 60) | 25 (18, 37) | 0.004 |
| BUN:creatinine ratio | 11.2 (8.7, 13.9) | 16.8 (13.3, 23) | <0.001 |
| Hemoglobin | 11.2 (9.6, 12.7) | 10.9 (9.2, 12.7) | 0.42 |
| Platelet count | 237 (173, 360) | 238 (172, 317) | 0.75 |
| Bicarbonate | 22.5 (19, 25) | 23 (20, 25) | 0.52 |
| Anion gap | 16 (14, 19) | 15 (12, 17) | 0.06 |
| Urine proteinuria | 2 (5.9%) | 57 (17.7%) | 0.13 |
| Urine-specific gravity | 1.012 (1.009,1.02) | 1.019 (1.013,1.024) | 0.002 |
| Diagnostic evaluation of AKI | |||
| Urinalysis | 34 (100%) | 322 (100%) | N/A |
| Clostridium difficile testing | 6 (17.6%) | 67 (20.8%) | 0.66 |
| Ultrasound | 16 (47.1%) | 54 (16.8%) | <0.001 |
| Medication use before AKI | |||
| PPI | 11 (32.4%) | 123 (38.2%) | 0.50 |
| NSAID | 4 (11.8%) | 113 (35.1%) | 0.006 |
| Antibiotic | 21 (61.8%) | 237 (73.6%) | 0.14 |
| Medication use after AKI (30 days) | |||
| Steroid use | 15 (44.1%) | 87 (27%) | 0.04 |
| Steroid use (excluding prior use) | 13 (40.6%) | 62 (22.5%) | 0.02 |
| Received ICI after AKI | 16 (47.1%) | 120 (37.3%) | 0.26 |
| Time to next ICI dose, days | 20.3 (10.2, 123.9) | 10.5 (0.1, 20.4) | 0.01 |
| Predicted probability of AIN | 0.49 (0.44, 0.56) | 0.15 (0.10, 0.25) | <0.001 |
| Immune-related adverse events | |||
| Dermatitis | 9 (26.5%) | 51 (15.8%) | 0.14 |
| Colitis | 8 (23.5%) | 48 (14.9%) | 0.21 |
| Hypophysitis | 4 (11.8%) | 24 (7.5%) | 0.33 |
| Pneumonitis | 3 (8.8%) | 32 (9.9%) | 0.99 |
| Adrenalitis | 2 (5.9%) | 60 (18.6%) | 0.09 |
| Thyroiditis | 2 (5.9%) | 25 (7.8%) | 0.99 |
| Hepatitis | 2 (5.9%) | 20 (6.2%) | 0.99 |
| Interstitial nephritis | 6 (17%) | 16 (5%) | 0.006 |
Only includes those with AKI and with complete data on components (n=356). Values obtained at AKI.
AIN, acute interstitial nephritis; AKI, acute kidney injury; eAIN, estimated acute interstitial nephritis; ICI, immune checkpoint inhibitor; NSAID, non-steroidal anti-inflammatory drug; PPI, proton pump inhibitor.