Tool Pinpoints Who May Benefit From COVID Convalescent Plasma

While a large meta-analysis of studies on convalescent plasma use early in the pandemic turned up no survival advantage for the typical patient hospitalized for COVID-19, researchers have mined the dataset to predict who may benefit.

Eva Petkova, PhD, of NYU Grossman School of Medicine in New York City, and colleagues devised a simple and freely available tool called the Convalescent Plasma Benefit Index Calculator that allows doctors to input certain patient criteria to determine if their patient may benefit from convalescent plasma (age, oxygen need, blood type, and history of either diabetes, heart disease, or pulmonary disease).

The meta-analysis and study on the validated treatment benefit index (TBI) tool derived from it were both published in JAMA Network Open.

Convalescent plasma was initially authorized by the FDA in August 2020, despite a lack of randomized trial data, and in February 2021, it was scaled back to only high-titer plasma for hospitalized patients early in their disease course who could not mount a sufficient immune response to COVID infection. More recently, FDA started allowing the therapy in the outpatient setting, but still limited treatment across the board to those with immunocompromised conditions.

Meta-Analysis

The COMPILE (Continuous Monitoring of Pooled International Trials of Convalescent Plasma for COVID-19 Hospitalized Patients) meta-analysis found no significant difference between patients receiving convalescent plasma or control patients based on the 11-point ordinal World Health Organization (WHO) scale, reported Andrea Troxel, ScD, also of NYU Grossman School of Medicine.

Odds ratios were 0.94 (95% credible interval [CrI] 0.74-1.19) for the median WHO score of 3 and 0.94 (95% CrI 0.69-1.30) for 7 or higher.

The meta-analysis comprised eight clinical trials that enrolled 1,138 patients to control therapy and 1,231 to convalescent plasma across Asia, Europe, North America, and South America. In six trials, controls received standard of care, and in two they received either non-convalescent plasma or saline. Patients were a mean age of 60, and about two-thirds were men.

Interestingly, while Troxel’s group cited “substantial heterogeneity of treatment effect sizes,” they also found that convalescent plasma was “minimally associated” with benefit in those with a baseline WHO score of 4, blood type A, and pre-existing diabetes, cardiovascular, and pulmonary disease.

TBI Tool

Using data from COMPILE, Petkova and colleagues identified the groups that had the highest likelihood of a large benefit from convalescent plasma (B1 group; 28% of the population), a modest benefit (B2 group; 42%), and those at risk for no benefit or even potential harm (B3 group; 31%):

• B1: OR 0.69 (95% CrI 0.48-1.06)
• B2: OR 0.82 (95% CrI 0.61-1.11)
• B3: OR 1.58 (95% CrI 1.14-2.17)

“Our treatment benefit index is designed to serve as a quick and effective tool for physicians to use in deciding when to administer convalescent plasma for COVID-19,” Petkova said in a statement.

Those falling into group B1 were more likely to have A or AB blood type (56% for each), and a history of cardiovascular disease (52%) or pulmonary disease (52%). And the B1 and B2 groups each had twice the rates of diabetes compared with the group that derived little benefit (40% vs 20%).

When clinicians input these patient variables, the tool calculates a patient’s TBI, dividing patients into three groups: substantial benefit from convalescent plasma, moderate benefit, and no expected benefit.

For example, in a 55-year-old patient who doesn’t need oxygen, but with a history of heart disease and with A blood type, the calculator returns a score of 0.69, indicating a chance for substantial benefit. But a 55-year-old with B blood type needing high-flow oxygen and with no history of heart disease is likely to see no benefit from convalescent plasma or even harm.

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