Table 1.
Demographic and clinical characteristics of patients, grouped by antibody dynamics
| Persistent (n=52)* | Slow waning (n=46) | Rapid waning (n=44) | Negative (n=19) | p value† | p value‡ | ||
|---|---|---|---|---|---|---|---|
| Patient characteristics | |||||||
| Age, years | 52 (43–60·5) | 44 (33–55) | 25·5 (27–48·5) | 42 (37–52) | 0·0001 | 0·0001 | |
| Sex | 0·76 | 0·70 | |||||
| Female | 14 (27%) | 13 (28%) | 10 (23%) | 3 (16%) | .. | .. | |
| Male | 38 (73%) | 33 (72%) | 34 (77%) | 16 (84%) | .. | .. | |
| Ethnicity | .. | .. | .. | .. | 0·020 | 0·065 | |
| Chinese | 31 (60%) | 27 (59%) | 19 (43%) | 4 (21%) | .. | .. | |
| Malay | 7 (13%) | 2 (4%) | 5 (11%) | 0 | .. | .. | |
| South Asian (Indian or Bangladeshi) | 9 (17%) | 11 (24%) | 14 (32%) | 11 (58%) | .. | .. | |
| Other | 5 (10%) | 6 (13%) | 6 (14%) | 4 (21%) | .. | .. | |
| Charlson comorbidity index | 0 (0–1) | 0 (0–1) | 0 (0–0) | 0 (0–0) | 0·032 | 0·012 | |
| Any comorbidity | 29 (56%) | 18 (39%) | 15 (34%) | 7 (37%) | 0·15 | 0·027 | |
| Diabetes | 17 (33%) | 6 (13%) | 3 (7%) | 1 (5%) | 0·0030 | 0·0005 | |
| Hypertension | 22 (42%) | 12 (26%) | 8 (18%) | 3 (16%) | 0·037 | 0·0081 | |
| Baseline symptoms | |||||||
| Duration of symptoms, days (n=158) | |||||||
| n | 50 | 46 | 44 | 18 | .. | .. | |
| Median (IQR) | 4 (2–7) | 2 (1–5) | 2 (0–6) | 0 (0–3) | 0·0008 | 0·0006 | |
| Fever (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| n (%) | 39 (78%) | 34 (74%) | 18 (41%) | 5 (26%) | <0·0001 | 0·0028 | |
| Cough (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| n (%) | 34 (68%) | 25 (54%) | 22 (50%) | 5 (26%) | 0·017 | 0·025 | |
| Dyspnoea (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| n (%) | 11 (22%) | 3 (7%) | 1 (2%) | 1 (5%) | 0·011 | 0·0014 | |
| Sore throat (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| n (%) | 18 (36%) | 15 (33%) | 19 (43%) | 3 (16%) | 0·21 | 0·86 | |
| Rhinorrhoea (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| n (%) | 13 (26%) | 9 (20%) | 13 (30%) | 3 (16%) | 0·60 | 0·69 | |
| Asymptomatic (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| n (%) | 3 (6%) | 7 (15%) | 13 (30%) | 11 (58%) | <0·0001 | 0·0008 | |
| Baseline investigations | |||||||
| White blood count, ×109/L (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| Median (IQR) | 5·40 (4·10–6·70) | 5·15 (4·50–6·90) | 6·35 (4·65–8·45) | 7·20 (4·60–9·90) | 0·079 | 0·19 | |
| Neutrophil count, ×109/L (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| Median (IQR) | 3·84 (2·62–5·40) | 3·63 (2·40–4·73) | 3·78 (2·51–5·12) | 4·14 (3·01–5·68) | 0·77 | 0·95 | |
| Lymphocyte count, ×109/L (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| Median (IQR) | 1·08 (0·79–1·44) | 1·13 (0·85–1·58) | 1·79 (1·22–2·56) | 1·73 (1·58–2·34) | 0·0001 | 0·0004 | |
| C-reactive protein, mg/L (n=153) | |||||||
| n | 49 | 44 | 42 | 18 | .. | .. | |
| Median (IQR) | 50·3 (13·0–76·6) | 9·85 (1·8–50·7) | 3·3 (1·4–7·6) | 1·85 (1·2–4·1) | 0·0001 | 0·0001 | |
| Lactate dehydrogenase, U/L (n=148) | |||||||
| n | 47 | 41 | 41 | 19 | .. | .. | |
| Median (IQR) | 589 (409–721) | 423 (364–538) | 362 (314–421) | 374 (319–439) | 0·0001 | 0·0001 | |
| Creatinine (μmol/L) (n=159) | |||||||
| n | 50 | 46 | 44 | 19 | .. | .. | |
| Median (IQR) | 79·5 (61–87) | 73 (62–83) | 72 (62–87) | 71 (64–81) | 0·70 | 0·26 | |
| Outcomes | |||||||
| Pneumonia | 47 (90%) | 28 (61%) | 12 (27%) | 1 (5%) | <0·0001 | <0·0001 | |
| Supplemental oxygen requirement | 33 (63%) | 9 (20%) | 2 (5%) | 0 | <0·0001 | <0·0001 | |
| Intensive care unit admission | 21 (40%) | 5 (11%) | 1 (2%) | 0 | <0·0001 | <0·0001 | |
| Mechanical ventilation | 8 (15%) | 0 | 0 | 0 | 0·0008 | <0·0001 | |
Data are median (IQR) or n (%). Categorical variables represented as number (percentage) and compared using Fisher's exact test. Continuous variables represented as median (interquartile range) and compared using Kruskal-Wallis test.
*
Two of 52 patients had missing data for baseline symptoms and baseline investigations; the rest of the data (demographics, medical history, and clinical outcomes) were complete.
†
Comparing all four groups independently.
‡
Persistent antibody group versus all other three groups (slow waning, rapid waning, and negative).