Table 2.
Univariate and multivariate analysis of factors associated with admission to hospital in the first and second waves in South Africa, March 5, 2020–March 27, 2021
| Percentage of patients in first wave (95% CI) | Percentage of patients in second wave (95% CI) | Unadjusted OR (95% CI) | Adjusted OR (95% CI)* | Adjusted OR (95% CI)† | |
|---|---|---|---|---|---|
| Age, years | |||||
| <40 | 24·3% (24·0–24·6) | 20·5% (20·3–20·8) | 1 (ref) | 1 (ref) | 1 (ref) |
| 40–64 | 51·2% (50·9–51·6) | 50·7% (50·4–51·1) | 1·17‡ (1·10–1·25) | 1·29‡ (1·21–1·38) | 1·22‡ (1·14–1·31) |
| ≥65 | 24·5% (24·2–24·8) | 28·7% (28·5–29·0) | 1·39‡ (1·26–1·53) | 1·46‡ (1·32–1·60) | 1·38‡ (1·25–1·52) |
| Sex | |||||
| Female | 55·8% (55·4–56·2) | 55·5% (55·2–55·8) | 1 (ref) | .. | .. |
| Male | 44·2% (43·8–44·6) | 44·5% (44·2–44·8) | 1·01 (0·98–1·05) | .. | .. |
| Race | |||||
| White | 9·2% (8·9–9·4) | 11·6% (11·2–11·9) | 1 (ref) | 1 (ref) | 1 (ref) |
| Black | 78·6% (78·2–79·0) | 68·1% (67·6–68·5) | 0·69‡ (0·61–0·77) | 0·56‡ (0·50–0·63) | 0·53‡ (0·47–0·60) |
| Mixed | 7·1% (6·8–7·3) | 13·6% (13·3–13·9) | 1·52‡ (1·29–1·80) | 1·22‡ (1·07–1·39) | 1·21‡ (1·06–1·38) |
| Indian | 5·2% (5·1–5·4) | 6·8% (6·6–7·0) | 1·03 (0·90–1·18) | 0·79‡ (0·67–0·93) | 0·77‡ (0·66–0·91) |
| Presence of comorbidities | |||||
| No | 39·3% (38·9–39·8) | 45·0% (44·6–45·3) | 1 (ref) | 1 (ref) | 1 (ref) |
| Yes | 60·7% (60·2–61·1) | 55·0% (54·7–55·4) | 0·79‡ (0·71–0·89) | 0·60‡ (0·55–0·66) | 0·60‡ (0·55–0·67) |
| Health sector | |||||
| Private sector | 51·6% (51·2–51·9) | 47·1% (46·8–47·4) | 1 (ref) | 1 (ref) | 1 (ref) |
| Public sector | 48·4% (48·1–48·8) | 52·9% (52·6–53·2) | 1·20‡ (1·02–1·40) | 1·63‡ (1·40–1·89) | 1·65‡ (1·41–1·92) |
| Province | |||||
| Western Cape | 16·5% (16·2–16·8) | 22·4% (22·2–22·7) | 1 (ref) | 1 (ref) | 1 (ref) |
| Eastern Cape | 12·4% (12·2–12·6) | 13·4% (13·2–13·6) | 0·79 (0·59–1·06) | 0·90 (0·66–1·24) | 0·97 (0·71–1·34) |
| Free State | 6·3% (6·1–6·5) | 3·3% (3·2–3·5) | 0·39‡ (0·28–0·55) | 0·49‡ (0·34–0·70) | 0·49‡ (0·34–0·70) |
| Gauteng | 34·9% (34·5–35·2) | 23·3% (23·0–23·5) | 0·49‡ (0·37–0·64) | 0·59‡ (0·44–0·78) | 0·55‡ (0·41–0·74) |
| KwaZulu-Natal | 18·1% (17·8–18·3) | 23·5% (23·3–23·8) | 0·96 (0·72–1·28) | 1·21 (0·89–1·65) | 1·14 (0·83–1·55) |
| Limpopo | 1·9% (1·8–2·0) | 5·2% (5·1–5·4) | 2·00‡ (1·42–2·83) | 2·60‡ (1·87–3·63) | 2·41‡ (1·74–3·34) |
| Mpumalanga | 3·0% (2·8–3·1) | 3·9% (3·8–4·1) | 0·97 (0·66–1·44) | 1·32 (0·91–1·92) | 1·30 (0·89–1·90) |
| North West | 5·6% (5·4–5·7) | 3·8% (3·6–3·9) | 0·49‡ (0·33–0·73) | 0·65‡ (0·43–0·99) | 0·62‡ (0·41–0·95) |
| Northern Cape | 1·4% (1·3–1·5) | 1·1% (1·1–1·2) | 0·59 (0·33–1·06) | 0·60 (0·35–1·04) | 0·62 (0·35–1·07) |
| Weekly national admission number | |||||
| Low (<3500) | 4·7% (4·5–4·9) | 3·0% (2·9–3·1) | 1 (ref) | .. | 1 (ref) |
| Medium (3500–5749) | 26·5% (26·2–26·8) | 13·4% (13·2–13·6) | 0·80‡ (0·65–0·97) | .. | 0·80‡ (0·66–0·96) |
| High (5750–7999) | 19·5% (19·2–19·8) | 14·7% (14·4–14·9) | 1·18 (0·94–1·48) | .. | 1·22 (0·98–1·52) |
| Very high (>8000) | 49·3% (48·9–49·6) | 68·9% (68·7–69·2) | 2·20‡ (1·71–2·85) | .. | 2·31‡ (1·81–2·95) |
For this analysis, the outcome variable was admission to hospital during wave 2 (event) versus admission to hospital during wave 1 (control), and the exposures were the characteristics of patients admitted to hospital. ORs represent the odds of being admitted to hospital in wave 2 among patients in the given exposure category versus the odds of being admitted to hospital in wave 2 among patients in the reference exposure category. OR=odds ratio.
*
Unadjusted for weekly admissions.
†
Adjusted for weekly admissions.
‡
Statistically significant estimates.