There are minimal data on post‐COVID‐19 readmissions in relatively low‐prevalence countries such as Australia. Data prior to COVID‐19 demonstrate that hospitalised patients have up to a 20% chance of a 30‐day unplanned readmission, representing a significant human, financial and resource burden. 1
We performed a single‐centre, observational cohort study of inpatients admitted to Austin Health from March to October 2020, investigating demographic, clinical, laboratory and treatment parameters associated with readmission to hospital within 6 months following initial inpatient management of COVID‐19. Patients with a single index admission were compared to those readmitted, then grouped according to reason for readmission (i.e. respiratory or COVID‐19‐specific symptoms, complications of COVID‐19, or unrelated presentation). Chi‐squared and rank sum tests were performed for univariate analysis using Stata MP16.1 (StataCorp, College Station, TX, USA).
Data from the index admission are summarised in Table 1. Of 169 patients admitted with COVID‐19 between March and October 2020 who survived to discharge, 24 (14.2%) were readmitted to hospital within 6 months (median, 36 days; interquartile range, 15–67 days). Ten (5.9%) patients re‐presented with respiratory or COVID‐19‐specific symptoms, five (3.0%) patients re‐presented with COVID‐19 complications, and nine (5.3%) patients re‐presented with unrelated problems (Supporting Information Table S1).
Table 1.
Demographic and clinical risk factors for re‐admission (at index admission)
| Total | Not readmitted | Readmitted | P‐value | |
|---|---|---|---|---|
| n | 169 | 145 | 24 | |
| Demographics | ||||
| Age, median (IQR) (years) | 59 (43, 74) | 59 (43, 76) | 57.5 (43, 67) | 0.54 |
| Age > 65 years | 65 (38.5%) | 58 (40.0%) | 7 (29.2%) | 0.31 |
| Age > 80 years | 31 (18.3%) | 29 (20.0%) | 2 (8.3%) | 0.17 |
| Sex (female) | 92 (54.4%) | 77 (53.1%) | 15 (62.5%) | 0.39 |
| Cardiac disease | 22 (13.2%) | 20 (14.0%) | 2 (8.3%) | 0.45 |
| Chronic liver disease | 1 (0.6%) | 1 (0.7%) | 0 (0.0%) | 0.68 |
| Chronic respiratory disease | 40 (24.0%) | 31 (21.7%) | 9 (37.5%) | 0.09 |
| Diabetes | 41 (24.6%) | 36 (25.2%) | 5 (20.8%) | 0.65 |
| Hypertension | 61 (36.5%) | 54 (37.8%) | 7 (29.2%) | 0.42 |
| ACEi or ARB treatment | 37 (61%) | 34 (63%) | 3 (43%) | 0.31 |
| Severity | ||||
| CCI (age adjusted), median (IQR) | 2 (0, 5) | 2 (0, 5) | 2 (1.5, 3.5) | 0.66 |
| Lung infiltrates >50% on CXR? | 23 (32%) | 21 (33%) | 2 (20%) | 0.40 |
| NIH COVID‐19 disease severity on admission† | ||||
| Asymptomatic | 1 (0.9%) | 1 (1%) | 0 (0%) | 0.72 |
| Mild | 16 (14.3%) | 13 (14%) | 3 (18%) | |
| Moderate | 53 (47.3%) | 43 (45%) | 10 (59%) | |
| Severe | 35 (31.3%) | 32 (34%) | 3 (18%) | |
| Critical | 7 (6.3%) | 6 (6%) | 1 (6%) | |
| ICU admission | 25 (15.2%) | 19 (13.4%) | 6 (26.1%) | 0.11 |
| Length of stay, median (IQR) | 5 (2, 10) | 5 (2, 9) | 7 (4, 20) | 0.04 |
| Laboratory parameters | ||||
| Haemoglobin, median (IQR) (g/L) | 135 (123, 146) | 135 (123, 146.5) | 137 (121, 146) | 0.74 |
| Lymphocytes, median (IQR) (×109/L) | 1.0 (0.7, 1.4) | 1.0 (0.7, 1.4) | 1.0 (0.6, 1.5) | 0.87 |
| Creatinine, median (IQR) (μmol/L) | 76 (60, 95) | 76.5 (60, 95) | 71 (60, 86) | 0.37 |
| CRP, median (IQR) (mg/L) | 40.7 (16.7, 109) | 40.7 (16.7, 98.3) | 48.1 (16.7, 126) | 0.85 |
| Procalcitonin, median (IQR) (μg/L) | 0.14 (0.05, 0.38) | 0.14 (0.06, 0.38) | 0.155 (0.05, 0.36) | 0.95 |
| Ferritin, median (IQR) (μg/L) | 424 (175, 778) | 424 (199, 770) | 413 (119, 1061) | 0.87 |
| LDH, median (IQR) (units/L) | 280 (235, 359) | 271 (224, 362) | 292 (264, 327) | 0.57 |
| Treatment | ||||
| Remdesivir | 25 (16.2%) | 23 (17.3%) | 2 (9.5%) | 0.37 |
| Corticosteroids | 62 (38.0%) | 52 (37.1%) | 10 (43.5%) | 0.56 |
| Supplemental nasal oxygen | 51 (38.1%) | 40 (34.8%) | 11 (57.9%) | 0.06 |
| High‐flow nasal oxygen | 9 (5.6%) | 6 (4.3%) | 3 (13.0%) | 0.09 |
| Mechanical ventilation | 9 (5.5%) | 8 (5.7%) | 1 (4.3%) | 0.79 |
| Subgroup analysis: respiratory or COVID‐19‐specific symptoms and COVID‐19 complications | ||||
| n | 160 | 145 | 15 | |
| ICU admission | 24 (15.3%) | 19 (13.4%) | 5 (33.3%) | 0.041 |
| Supplemental nasal oxygen | 48 (37.8%) | 40 (34.8%) | 8 (66.7%) | 0.030 |
| High‐flow nasal oxygen | 9 (5.9%) | 6 (4.3%) | 3 (20.0%) | 0.014 |
Based on NIH COVID‐19 Treatment Guidelines. 2
ACEi, angiotensin‐converting enzyme inhibitor; ARB, angiotensin receptor blocker; CCI, Charlson Comorbidity Index (age adjusted); CRP, C‐reactive protein; CXR, chest X‐ray; ICU, intensive care unit; IQR, interquartile range, LDH, lactate dehydrogenase; NIH, National Institutes of Health.
In whole cohort analysis, increased length of stay during index admission was significantly associated with readmission (5 days vs 7 days, P = 0.04). A non‐significant increase in readmission was noted in patients with pre‐existing chronic respiratory disease, patients requiring supplemental oxygen, and patients admitted to the intensive care unit (ICU). In sub‐group analysis of only those patients who re‐presented with respiratory or COVID‐19‐specific symptoms or complications of COVID‐19 (n = 15), ICU admission (P = 0.04), supplemental oxygen (P = 0.03) and high‐flow nasal oxygen (HFNO) (P = 0.01) were significantly associated with readmission. Of those who re‐presented within 30 days of index admission (n = 12), readmission was increased in patients with pre‐existing chronic respiratory disease (21.7% vs 41.7%, P = 0.12), and a significant association was found with HFNO (P = 0.004).
To our knowledge, this is the first study investigating readmission trends following hospitalisation with COVID‐19 in a low‐prevalence country. Our data compare with a large US registry study that reported a 60‐day re‐presentation rate of 9%, a COVID‐19‐related re‐presentation rate of 45%, and included respiratory comorbidity as a risk for re‐presentation. 3 We found a positive association between length of stay and readmission, in contrast to other studies where premature discharge was thought to contribute to ‘bounce‐back’ admissions. 3 , 4
Although limited by small numbers and single‐centre follow up, we found an association between parameters indicating a more severe illness course (ICU, HFNO, length of stay) and readmission, although no association between National Institutes of Health (NIH)‐calculated severity of index illness at presentation 2 and readmission. International experience investigating early readmission after COVID‐19 hospitalisation shows mixed results; 4 , 5 however, an increased likelihood of readmission in patients requiring HFNO in index admission has been associated with poor prognosis in other studies. 6
As length of stay, ICU admission, supplemental oxygen requirement and HFNO were associated with readmission for COVID‐19 or associated complications, this group of patients should be a focus for targeted post‐acute care.
Supporting information
Table S1 Reason for re‐admission.
References
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Associated Data
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Supplementary Materials
Table S1 Reason for re‐admission.