Table 1.
Patient Characteristics at Baseline
| Patient Characteristics* | Balanced Crystalloids (n = 824) | Saline (n = 817) |
|---|---|---|
| Age, yr | 60 (48–69) | 60 (47–69) |
| Men, n (%) | 451 (54.7) | 448 (54.8) |
| White, n (%) | 617 (74.9) | 618 (75.6) |
| Weight, kg† | 78 (64–98) | 77 (64–94) |
| Chronic comorbidities, n (%)‡ | ||
| Pulmonary | 204 (24.8) | 214 (26.2) |
| Chronic heart failure | 200 (24.3) | 184 (22.5) |
| Chronic liver disease | 177 (21.5) | 198 (24.2) |
| Diabetes | 310 (37.6) | 279 (34.1) |
| Drug abuse | 38 (4.6) | 58 (7.1) |
| Metastatic malignancy | 78 (9.5) | 82 (10.0) |
| AIDS | 20 (2.4) | 21 (2.6) |
| Renal | ||
| Chronic kidney disease, stage III or greater§ | 169 (20.5) | 157 (19.2) |
| Prior renal replacement therapy receipt | 91 (11.0) | 92 (11.3) |
| Source of admission to the ICU, n (%) | ||
| Emergency department | 464 (56.3) | 458 (56.1) |
| Transfer from another hospital | 179 (21.7) | 180 (22.0) |
| Hospital ward | 154 (18.7) | 159 (19.5) |
| Operating room | 15 (1.8) | 8 (1.0) |
| Another ICU within the hospital | 9 (1.1) | 10 (1.2) |
| Outpatient | 3 (0.4) | 2 (0.2) |
| Sepsis as primary diagnosis at ICU admission, n (%)|| | 577 (70.0) | 573 (70.1) |
| Suspected source of infection, n (%)|| | ||
| Pulmonary | 189 (32.8) | 164 (28.6) |
| Urinary | 97 (16.8) | 94 (16.4) |
| Intraabdominal | 78 (13.5) | 83 (14.5) |
| Skin and soft tissue | 35 (6.1) | 36 (6.3) |
| Bloodstream | 22 (3.8) | 28 (4.9) |
| Other | 43 (7.4) | 51 (8.9) |
| Multiple sources suspected | 83 (14.4) | 87 (15.2) |
| No confirmed source | 30 (5.2) | 30 (5.2) |
| Vasopressors, n (%) | 289 (35.1) | 270 (33.0) |
| Vasopressor dose, norepinephrine equivalent, μg/kg/min¶ | 0.11 ± 0.27 | 0.11 ± 0.30 |
| Mean arterial pressure, mm Hg | 73 (62–87) | 74 (63–88) |
| Mechanical ventilation, n (%) | 324 (39.3) | 333 (40.8) |
| SOFA score** | 7 (5–10) | 8 (5–11) |
| White blood cell count, 103/μl†† | 13.9 (8.3–19.9) | 12.7 (8.3–19.0) |
| Platelet count, 103/μl†† | 189 (116–284) | 189 (107–280) |
| Hb, g/dl†† | 10.4 (8.7–12.2) | 10.2 (8/7–12.3) |
| Baseline creatinine, mg/dl‡‡ | 0.88 (0.67–1.21) | 0.87 (0.66–1.23) |
| Acute kidney injury, stage II or greater§§ | 207 (25.1) | 208 (25.4) |
Definition of abbreviation: SOFA = Sequential Organ Failure Assessment.
Continuous data are presented as median (25th percentile–75th percentile) or mean ± SD. Categorical data are presented as number (n) and percentage (%). The only significant difference in baseline characteristics between the two study groups was history of drug abuse (P = 0.03).
Information on weight at ICU admission was missing for 22 patients (8 in the balanced crystalloids group and 14 in the saline group).
Chronic comorbidities are defined by the Elixhauser Comorbidity Index, a method for measuring patient comorbidity based on the International Classification of Diseases, 9th Edition, Clinical Modification System and the International Classification of Diseases, 10th Edition, Clinical Modification System (ICD-10-CM) diagnosis codes, found in administrative data (40, 41).
Chronic kidney disease stage III or greater is defined as a glomerular filtration rate less than 60 ml/min per 1.73 m2 as calculated by the Chronic Kidney Disease Epidemiology Collaboration Equation (42) using the patient’s baseline creatinine value.
Of 1,641 patients admitted to the medical ICU with a diagnosis of sepsis by ICD-10-CM criteria, physician manual chart review determined that the primary diagnosis at the time of ICU admission was sepsis for 1,150 patients (70.1%), 577 in the balanced crystalloids group and 573 in the saline group. For these patients, the suspected source of infection was determined.
Vasopressor dose represents the first value, in norepinephrine equivalents (Table E2), among patients receiving vasopressors on the day of ICU admission.
The SOFA score, also known as the Sepsis-related Organ Failure Assessment score (32), was calculated using data collected from the day of ICU admission. Baseline SOFA was missing for 5 patients (3 patients in balanced crystalloids group and 2 patients in saline group).
Baseline white blood cell count was missing for 7 (0.8%) patients in the balanced crystalloids group and 8 (1.0%) in the saline group. Baseline platelet count was missing for 1 (0.1%) patients in the balanced crystalloids group and 4 (0.5%) in the saline group. Baseline Hb was missing for 3 (0.4%) patients in the balanced crystalloids group and 5 (0.6%) in the saline group.
Baseline creatinine for the study was defined as the lowest plasma creatinine measured in the 12 months before hospitalization if available; otherwise, as the lowest plasma creatinine measured between hospitalization and ICU admission, using an estimated creatinine only for patients without an available plasma creatinine between 12 months before hospitalization and the time of ICU admission. The baseline creatinine was estimated for 107 (13.0%) patients in the balanced crystalloids group and 110 (13.5%) in the saline group.
Acute kidney injury stage II or greater is defined according to Kidney Disease: Improving Global Outcomes creatinine criteria (43) as a first measured plasma creatinine value after ICU admission at least 200% of the baseline value or both 1) greater than 4.0 mg/dl and 2) increased at least 0.3 mg/dl from the baseline value.