Table 3.
Subgroup Analysis of the Associations Between Anion Gap and 30-Day All-Cause Mortality
| Characteristic | N | HR (95% CI) | P value | P for Interaction |
|---|---|---|---|---|
| Age, years | 0.2008 | |||
| <72.9 | 621 | 1.14 (1.11, 1.17) | <0.0001 | |
| ≥72.9 | 627 | 1.12 (1.10, 1.15) | <0.0001 | |
| Gender | 0.6247 | |||
| Female | 511 | 1.12 (1.09, 1.14) | <0.0001 | |
| Male | 737 | 1.13 (1.11, 1.15) | <0.0001 | |
| Ethnicity | 0.0041 | |||
| White | 855 | 1.16 (1.13, 1.19) | <0.0001 | |
| Black | 83 | 1.07 (1.00, 1.14) | 0.0491 | |
| Other | 310 | 1.11 (1.08, 1.14) | <0.0001 | |
| CHF | 0.7634 | |||
| No | 721 | 1.13 (1.10, 1.15) | <0.0001 | |
| Yes | 527 | 1.14 (1.11, 1.18) | <0.0001 | |
| CAD | <0.0001 | |||
| No | 543 | 1.10 (1.07, 1.12) | <0.0001 | |
| Yes | 705 | 1.19 (1.15, 1.22) | <0.0001 | |
| AFIB | 0.4855 | |||
| No | 660 | 1.13 (1.11, 1.16) | <0.0001 | |
| Yes | 588 | 1.13 (1.10, 1.16) | <0.0001 | |
| Renal disease | 0.0383 | |||
| No | 972 | 1.15 (1.12, 1.18) | <0.0001 | |
| Yes | 276 | 1.11 (1.08, 1.15) | <0.0001 | |
| Liver disease | 0.6737 | |||
| No | 1210 | 1.13 (1.11, 1.15) | <0.0001 | |
| Yes | 38 | 1.10 (0.95, 1.27) | 0.2030 | |
| Stroke | 0.4105 | |||
| No | 1185 | 1.13 (1.11, 1.15) | <0.0001 | |
| Yes | 63 | 1.25 (1.04, 1.49) | 0.0166 | |
| Pneumonia | 0.0698 | |||
| No | 845 | 1.14 (1.12, 1.16) | <0.0001 | |
| Yes | 403 | 1.11 (1.06, 1.15) | <0.0001 | |
| Respiratory failure | 0.0517 | |||
| No | 635 | 1.15 (1.12, 1.17) | <0.0001 | |
| Yes | 613 | 1.12 (1.09, 1.15) | <0.0001 | |
| ARDS | 0.3866 | |||
| No | 1225 | 1.14 (1.12, 1.16) | <0.0001 | |
| Yes | 23 | 1.04 (0.90, 1.20) | 0.5706 | |
| Malignancy | 0.9078 | |||
| No | 1111 | 1.14 (1.12, 1.16) | <0.0001 | |
| Yes | 137 | 1.16 (1.10, 1.22) | <0.0001 | |
| Albumin, g/dL | 0.0812 | |||
| <3.1 | 315 | 1.10 (1.07, 1.13) | <0.0001 | |
| ≥3.1 | 384 | 1.16 (1.11, 1.21) | <0.0001 | |
| Bicarbonate, mg/dL | 0.4811 | |||
| <20 | 597 | 1.11 (1.09, 1.14) | <0.0001 | |
| ≥20 | 651 | 1.14 (1.09, 1.19) | <0.0001 | |
| Bilirubin, mg/dL | 0.0259 | |||
| <0.7 | 418 | 1.14 (1.09, 1.19) | <0.0001 | |
| ≥0.7 | 441 | 1.13 (1.10, 1.15) | <0.0001 | |
| Sodium, mmol/L | 0.1491 | |||
| <135 | 502 | 1.12 (1.09, 1.15) | <0.0001 | |
| ≥135 | 746 | 1.15 (1.12, 1.17) | <0.0001 | |
| Potassium, mmol/L | 0.1660 | |||
| <3.7 | 562 | 1.15 (1.11, 1.20) | <0.0001 | |
| ≥3.7 | 686 | 1.13 (1.11, 1.15) | <0.0001 | |
| Lactate, mmol/L | 0.5146 | |||
| <1.8 | 465 | 1.10 (1.05, 1.16) | 0.0001 | |
| ≥1.8 | 494 | 1.10 (1.08, 1.13) | <0.0001 | |
| BUN, mg/dL | 0.1278 | |||
| <27 | 591 | 1.14 (1.10, 1.18) | <0.0001 | |
| ≥27 | 657 | 1.12 (1.10, 1.15) | <0.0001 | |
| PT, second | 0.0816 | |||
| <14.5 | 604 | 1.15 (1.10, 1.20) | <0.0001 | |
| ≥14.5 | 606 | 1.12 (1.10, 1.14) | <0.0001 | |
| INR | 0.0708 | |||
| <1.3 | 498 | 1.17 (1.11, 1.23) | <0.0001 | |
| ≥1.3 | 713 | 1.12 (1.10, 1.14) | <0.0001 | |
| APTT, second | 0.7576 | |||
| <32.9 | 610 | 1.12 (1.07, 1.16) | <0.0001 | |
| ≥32.9 | 606 | 1.13 (1.11, 1.15) | <0.0001 | |
| WBC, 109 /L | 0.6960 | |||
| <10.8 | 624 | 1.12 (1.09, 1.15) | <0.0001 | |
| ≥10.8 | 622 | 1.15 (1.12, 1.18) | <0.0001 | |
| Platelet, 109 /L | 0.1366 | |||
| <184 | 620 | 1.12 (1.09, 1.14) | <0.0001 | |
| ≥184 | 627 | 1.18 (1.14, 1.22) | <0.0001 | |
| Hematocrit, % | 0.0157 | |||
| <29.6 | 619 | 1.11 (1.08, 1.13) | <0.0001 | |
| ≥29.6 | 629 | 1.19 (1.15, 1.23) | <0.0001 | |
| Hemoglobin, g/dL | 0.0100 | |||
| <9.9 | 602 | 1.11 (1.09, 1.14) | <0.0001 | |
| ≥9.9 | 645 | 1.19 (1.15, 1.23) | <0.0001 | |
| Creatinine, mEq/L | 0.3452 | |||
| <1.3 | 605 | 1.11 (1.06, 1.16) | <0.0001 | |
| ≥1.3 | 643 | 1.13 (1.10, 1.15) | <0.0001 | |
| Glucose, mg/dL | 0.1169 | |||
| <114 | 616 | 1.12 (1.10, 1.15) | <0.0001 | |
| ≥114 | 632 | 1.15 (1.12, 1.18) | <0.0001 | |
| Chloride, mmol/L | 0.0027 | |||
| <102 | 611 | 1.11 (1.09, 1.14) | <0.0001 | |
| ≥102 | 637 | 1.17 (1.14, 1.20) | <0.0001 | |
| SBP, mmHg | 0.4507 | |||
| <103 | 621 | 1.13 (1.11, 1.15) | <0.0001 | |
| ≥103 | 621 | 1.13 (1.08, 1.17) | <0.0001 | |
| DBP, mmHg | 0.0629 | |||
| <57 | 620 | 1.14 (1.12, 1.17) | <0.0001 | |
| ≥57 | 622 | 1.12 (1.09, 1.15) | <0.0001 | |
| MBP, mmHg | 0.0626 | |||
| <72 | 619 | 1.14 (1.12, 1.17) | <0.0001 | |
| ≥72 | 624 | 1.10 (1.07, 1.14) | <0.0001 | |
| Heart rate, beats/minute | 0.2923 | |||
| <89 | 621 | 1.14 (1.11, 1.17) | <0.0001 | |
| ≥89 | 622 | 1.13 (1.11, 1.16) | <0.0001 | |
| Respiratory rate, beats/minute | 0.0195 | |||
| <20 | 617 | 1.12 (1.08, 1.17) | <0.0001 | |
| ≥20 | 626 | 1.13 (1.10, 1.15) | <0.0001 | |
| Temperature, °C | 0.2451 | |||
| <36.7 | 593 | 1.13 (1.10, 1.16) | <0.0001 | |
| ≥36.7 | 599 | 1.16 (1.12, 1.20) | <0.0001 | |
| SPO2, % | 0.4524 | |||
| <97 | 620 | 1.14 (1.11, 1.16) | <0.0001 | |
| ≥97 | 620 | 1.13 (1.09, 1.17) | <0.0001 | |
| SOFA score | 0.6956 | |||
| <7 | 556 | 1.10 (1.05, 1.16) | 0.0003 | |
| ≥7 | 692 | 1.12 (1.10, 1.14) | <0.0001 | |
| SAPSII score | 0.6197 | |||
| <46 | 594 | 1.12 (1.06, 1.18) | <0.0001 | |
| ≥46 | 654 | 1.11 (1.09, 1.13) | <0.0001 | |
| Vasopressor use | 0.3629 | |||
| No | 232 | 1.09 (1.01, 1.18) | 0.0213 | |
| Yes | 1016 | 1.13 (1.11, 1.15) | <0.0001 | |
| RRT | 0.0001 | |||
| No | 1045 | 1.14 (1.12, 1.17) | <0.0001 | |
| Yes | 203 | 1.07 (1.03, 1.11) | 0.0012 |
Abbreviations: CHF, congestive heart failure; CAD, coronary artery disease; AFIB, atrial fibrillation; ARDS, acute respiratory distress syndrome; BUN, blood urea nitrogen; PT, prothrombin time; INR, international normalized ratio; APTT, activated partial thromboplastin time; WBC, white blood cell; SBP, systolic blood pressure; DBP, diastolic blood pressure; MBP, mean blood pressure; SOFA, Sequential Organ Failure Assessment; SAPSII, Simplified Acute Physiology Score II; RRT, renal replacement therapy.