Abstract
This case series characterizes the demographics, health services use, and vital status and discharge dispositions of patients with polymerase chain reaction–confirmed coronavirus disease 2019 (COVID-19) hospitalized in the Kaiser Permanente Northern California health system in March 2020.
Coronavirus disease 2019 (COVID-19) has resulted in increased hospital and intensive care unit (ICU) use. In the United States, few reports have characterized patients treated outside of the ICU.1 Northern California was an early epicenter of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) community transmission in the United States. We report hospitalization and ICU admissions from Kaiser Permanente Northern California (KPNC), a regional integrated health care system serving 4.4 million members, constituting 30% of the area’s insured population.
Methods
We performed a retrospective cohort study of adults (≥18 years) with nasal/throat swabs positive for SARS-CoV-2 by polymerase chain reaction hospitalized between March 1, 2020, and March 31, 2020, at 21 KPNC hospitals. Tests were approved by infectious disease physicians based on public health and local guidelines. Patients were triaged according to clinician judgment. No patients were lost to follow-up.
We characterized patients by demographics, comorbid disease,2 severity of illness,2 ICU use, laboratory/chest film data, and highest level of respiratory support. Patients were treated according to national guidelines for pneumonia and acute respiratory distress syndrome. We report numbers (percentages) for binary/categorical variables and medians (interquartile ranges) for continuous variables. As of April 9, 2020, 14.8% of the cohort was still hospitalized. In-hospital mortality estimates were calculated for patients with discharge dispositions as of April 9, 2020.
The KPNC institutional review board approved the project with a waiver of informed consent.
Results
Of 16 201 tests in adults, results from 1299 patients (8.0%) were positive for SARS-CoV-2. Of these patients, 377 (29.0%) were treated as inpatients and 113 (8.7%) were treated in the ICU.
The median age was 61.0 years (interquartile range, 50.0-73.0 years); 56.2% were men (Table). The most common comorbidity was hypertension (n = 164, 43.5%). Of 166 patients who underwent testing for influenza A/B or respiratory syncytial virus (44.0% of the cohort), none tested positive. Bilateral infiltrates on chest film were seen in 63.4% (n = 239). Overall, 34 patients (9.0%) received a prednisone-equivalent dosage of 20 mg/d or more.
Table. Characteristics of Adult Patients Hospitalized With Coronavirus Disease 2019 in Northern Californiaa.
| No. (%) | |||
|---|---|---|---|
| All adults (N = 377) | Adults treated on general ward or intermediate care unit (n = 264) | Adults treated in intensive care unit (n = 113) | |
| Age, median (IQR), y | 61.0 (50.0-73.0) | 60.0 (49.0-72.0) | 63.0 (53.0-73.0) |
| Sex | |||
| Male | 212 (56.2) | 138 (52.3) | 74 (65.4) |
| Female | 165 (43.8) | 126 (47.7) | 39 (34.5) |
| COPS2, median (IQR)b | 13.0 (10.0-33.0) | 13.0 (10.0-35.0) | 10.0 (9.0-32.0) |
| Comorbidities | |||
| Hypertension | 164 (43.5) | 106 (40.2) | 58 (51.3) |
| Diabetes | 118 (31.3) | 73 (27.7) | 45 (39.8) |
| Chronic kidney disease | 48 (12.7) | 36 (13.6) | 12 (10.6) |
| COPD or asthma | 28 (7.4) | 20 (7.6) | 8 (7.1) |
| Congestive heart failure | 22 (5.8) | 18 (6.8) | 4 (3.5) |
| Liver cirrhosis | 21 (5.6) | 14 (5.3) | 7 (6.2) |
| Malignancy | 18 (4.8) | 12 (4.5) | 6 (5.3) |
| LAPS2, median (IQR)c | 72.0 (52.0-95.0) | 64.0 (49.0-83.0) | 93.0 (73.0-115.0) |
| Chief symptom in emergency department | |||
| Shortness of breath | 185 (49.1) | 118 (44.7) | 67 (59.3) |
| Fever | 127 (33.7) | 88 (33.3) | 39 (34.5) |
| Cough | 120 (31.8) | 80 (30.3) | 40 (35.4) |
| Initial laboratory tests, median (IQR)d | |||
| White blood cell count, ×109/L | 6.4 (4.7-8.5) | 6.2 (4.6-8.1) | 7.3 (5.4-9.2) |
| Reference range | 3.7-11.1 | ||
| Absolute neutrophil count, ×109/L | 4.8 (3.3-6.7) | 4.3 (3.1-5.9) | 5.6 (3.9-7.4) |
| Reference range | 1.8-7.9 | ||
| Absolute lymphocyte count, ×109/L | 1.0 (0.7-1.4) | 1.0 (0.7-1.4) | 0.9 (0.7-1.2) |
| Reference range | 0.9-3.2 | ||
| Creatinine, mg/dL | 0.9 (0.7-1.1) | 0.9 (0.7-1.0) | 0.9 (0.8-1.2) |
| Reference range | ≤1.11 | ||
| Lactate, mmol/L | 1.2 (1.0-1.6) | 1.2 (0.9-1.5) | 1.4 (1.0-1.8) |
| Reference range | 0.5-1.9 | ||
| AST, U/L | 36.0 (25.0-56.0) | 34.0 (24.0-55.0) | 39.0 (31.0-58.0) |
| Reference range | 10-40 | ||
| ALT, U/L | 29.0 (19.0-47.0) | 28.0 (18.0-48.0) | 29.0 (21.0-41.0) |
| Reference range | 0-41 | ||
| Total bilirubin, mg/dL | 0.6 (0.4-0.8) | 0.5 (0.4-0.7) | 0.6 (0.5-0.9) |
| Reference range | 0.2-1.2 | ||
| LDH, U/L | 302 (224-398) | 288 (212-365) | 345 (274-489) |
| Reference range | ≤270 | ||
| Viral respiratory panel | |||
| Influenza A/B | 0 | 0 | 0 |
| Respiratory syncytial virus | 0 | 0 | 0 |
| Initial chest film result, opacities | |||
| None | 62 (16.4) | 55 (20.8) | 7 (6.2) |
| Unilateral | 61 (16.2) | 51 (19.3) | 10 (8.8) |
| Bilateral | 239 (63.4) | 143 (54.2) | 96 (85.0) |
| Highest level of respiratory support | |||
| Nasal cannula/face mask | 150 (39.8) | 145 (54.9) | 5 (4.4) |
| High-flow oxygen | 12 (3.2) | 8 (3.0) | 4 (3.5) |
| Noninvasive ventilation | 8 (2.1) | 7 (2.7) | 1 (<1) |
| Invasive ventilation | 110 (29.2) | 7 (2.7)e | 103 (91.2) |
| Received steroid equivalent to prednisone ≥20 mg/d while inpatient | 34 (9.0) | 20 (7.6) | 14 (12.4) |
Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; COPD, chronic obstructive pulmonary disease; COPS2, Co-morbidity Point Score version 2; IQR, interquartile range; LAPS2, Laboratory-based Acute Physiology Score version 2; LDH, lactate dehydrogenase.
SI conversion factors: To convert ALT, AST, and LDH to μkat/L, multiply by 0.0167; bilirubin to µmol/L, multiply by 17.104; creatinine to μmol/L, multiply by 88.4; and lactate to mg/dL, divide by 0.111.
Hospitalizations can occur as observations or inpatient admissions. If a patient had a rehospitalization, data from the first hospitalization are reported.
COPS2 is assigned based on all diagnoses incurred by a patient in the 12 months preceding the index hospitalization. Prior to the pandemic, the univariate relationship of COPS2 score with 30-day mortality was as follows: 0-39, 1.7%; 40-64, 5.2%; and ≥65, 9.0%.2
LAPS2 is assigned based on a patient’s worst vital signs, pulse oximetry, neurological status, and 16 laboratory test results in the 72 hours preceding hospitalization. Prior to the pandemic, the univariate relationship of an admission LAPS2 score with 30-day mortality was as follows: 0-59, 1.0%; 60-109, 5.0%; and ≥110, 13.7%.2
Most patients underwent these laboratory tests (>97% for cell counts and creatinine, 88% for lactate, 80% for liver function tests, and 52% for LDH).
Patients treated in intermediate care units capable of mechanical ventilation.
Most patients were treated on the general ward or intermediate care unit (n = 264 [70.0%]); of whom 54.9% received supplemental oxygen through nasal cannula/face mask. A total of 113 inpatients (30.0%) required ICU admission and 110 (29.2%) received invasive mechanical ventilation.
Patients aged 60 to 69 years represented the most common age group both hospitalized (n = 93 [24.6%]) and admitted to the ICU (n = 31 [27.4%]) (Figure). However, adults of all ages were admitted, and the proportion of younger and middle-aged adults (≤59 years) who were hospitalized (n = 172 [45.6%]) was similar to the proportion of older adults (≥60 years) who were hospitalized (n = 205 [54.4%]).
Figure. Distribution by Age Group of Adult Patients Admitted to General Ward and Intensive Care Unit With Coronavirus Disease 2019.
Patients treated in intermediate care units are grouped under general ward.
Of 321 patients with discharge dispositions, 50 (15.6%) died in the hospital. Of 253 patients treated on the ward with discharge dispositions, 16 (6.3%) died. Of 68 patients treated in the ICU with discharge dispositions, 34 (50.0%) died.
Discussion
Estimates of patients with positive SARS-CoV-2 test results who were (1) admitted to a KPNC hospital (29.0%) and (2) treated in an ICU (8.7%) are broadly similar to those from the US Centers for Disease Control and Prevention (21%-31% and 5%-12%, respectively) and contain less missing data.3 The KPNC estimate of ICU admissions using positive tests as denominator (8.7%) is lower than Italy (12%)4 but higher than China (5%).5 Given the differences in care among countries, it is important to report data from the United States. The KPNC mortality estimate is preliminary but reasonably consistent with the early Seattle, Washington, experience.1
Unlike previous studies, adults across age groups, not just elderly individuals, required inpatient care, with persons aged 60 to 69 years most commonly hospitalized. These findings underscore the importance of public health interventions that prevent transmission for the entire public to mitigate hospital surges.
The major limitation of this study is that these data represent an early phase of SARS-CoV-2 transmission in California. Several key factors were changing over this period, including implementation of physical distancing measures and testing speed, which could affect future results.
Section Editor: Jody W. Zylke, MD, Deputy Editor.
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