Table 2.
Propensity score‐matched studies reported to date
| Type of study | Country | Patients + control | Median days after hospitalization | Baseline recipient WHO score* | CCP volume transfused (ml) | Statistically significant outcomes | Refs |
|---|---|---|---|---|---|---|---|
| Retrospective | Mount Sinai, NY, USA | 39 + 156 | 4 |
5 (87%) 6 (10%) |
250 + 250 | On day 14 oxygen requirements worsened in 17·9% of plasma recipients vs. 28·2% of controls (aOR 0·86). Survival improved in plasma recipients (aHR 0·34) | [5] |
| Providence, RI, USA | 64 + 177 | >2 (<10 from onset of symptoms: median 7) |
4 (70%) 5 (30%) |
n.a. (2 units) | No significant differences in incidence of in‐hospital mortality (12·5% and 15·8%; aHR 0·93) or overall rate of hospital discharge (RR 1·28, although increased among patients > 65 years) | [8] | |
| Montefiore Medical Center, NY, USA | 90 + 258 | <3 (3–7 days from onset of symptoms) | 5–6 (<24 h mechanical ventilation) | 200 |
Anti‐S IgG titre ≥ 1:2,430 (median 1:47,385) recipients < 65 years had fourfold lower mortality and fourfold lower deterioration in oxygenation or mortality at day 28 |
[4] | |
| Washington, USA | 263 + 263 | n.a. | n.a. | 245 (median) | Reduced 7‐day (9·1 vs. 19·8%) and 14‐day mortality (14·8 vs. 23·6%), but not 28‐day mortality, and longer hospital stay | [26] | |
| China | 163 + 163 | n.a. | n.a. | 300 | Hospital stay in the CCP group was significantly longer than in the matched control group (P < 0·0001). | [27] | |
| Prospective | Houston, USA | 136 + 251 | n.a. |
3 (9%) 4 (63%) 5 (18%) 6 (10%) 7 (1%) |
300 (1–2 units) | Reduction in mortality within 28 days, specifically in patients transfused < 72 h of admission with CCP with an anti‐RBD titre ≥ 1:1350 (i.e. ˜80% probability of a live virus in vitro neutralization titre of ≥1:160 [28]) | [6] |
| 341 + 594 | n.a. | 300 (1‐2 units) | Reduced 28‐day (aHR = 2·09 for controls) and 60‐day (5·7% vs. 10·7%; aHR = 1·82 for controls) mortality in those transfused with anti‐RBD ≥ 1:1350 within 72 h post‐hospitalization. Optimal window of 44 h to maximize benefit in 60‐day mortality (4% vs. 12·3%). 91% received CCP with an anti‐RBD titre ≥ 1:1350. Median S/CO ratio = 24 using Ortho Vitros. | [7] |
None of these studies tittered neutralizing antibodies in either the donors or recipients using the plaque reduction neutralization test.
WHO, World Health Organization; CCP, COVID‐19 convalescent plasma; Refs, references; aOR, adjusted odds ratio; aHR, adjusted hazard ratio; RR, relative risk; RBD, receptor binding domain; S/CO, significant cut‐off.
The WHO score [20] ranges from 0 to 8: 0: no clinical or virological evidence of infection; 1: no limitations of activities; 2: limitations of activities; 3: hospitalized, no oxygen therapy; 4: oxygen by mask or nasal prongs; 5: non‐invasive ventilation or high‐flow oxygen; 6: intubation and mechanical ventilation; 7: ventilation + additional organ support ‐ pressors, renal replacement therapy, extracorporeal membrane oxygenation; and 8: death.