Adults with hematologic malignancies and COVID-19 infection have a substantially higher risk of death compared with children with hematologic malignancies and COVID-19, according to a study published in Blood.
“While we don’t know for sure why this happens, it has been hypothesized that children may mount a more effective immune response to the SARS-CoV-2 virus,” corresponding study author Lisa Hicks, MD, of St. Michael’s Hospital in Toronto, Ontario, told ASH Clinical News. “There is also a body of literature suggesting that children may sometimes be infected with a lower ‘dose’ of the virus than adults due to differences in nasal receptors that the virus is thought to exploit.”
In this report, Dr. Hicks and colleagues conducted a systematic review and meta-analysis of studies published since January 2019 that reported outcomes of patients with cancer and COVID-19. Only studies reporting data on patients with hematologic malignancies (bone marrow failure syndromes such as myelodysplastic syndromes, acute leukemias, lymphomas, plasma cell dyscrasias, and/or myeloproliferative neoplasms [MPNs]) were eligible for inclusion in the final meta-analysis.
The pooled risk of death among patients with hematologic malignancies and COVID-19 comprised the primary outcome of the meta-analysis. The investigators examined this risk in both adult and pediatric patient populations. Additional secondary outcomes of interest were the proportion of hospitalized patients who required admission to the intensive care unit (ICU) and mechanical and noninvasive ventilation support.
The researchers identified 34 adult studies (including a total of 3,240 adult patients) and 5 pediatric studies (including a total of 102 children and adolescents). Overall, 3,377 patients had hematologic malignancies and COVID-19.
In the adult studies, the pooled risk of death associated with hematologic malignancies and concomitant COVID-19 infection was 34%. In an analysis restricted to mortality in hospitalized patients (n=2,361), the pooled risk of mortality was slightly higher, at 39%.
The pooled risk of death associated with hematologic malignancies and COVID-19 was substantially lower in the pediatric studies: 4%.
When the researchers stratified patients according to age, they found that younger patients (<60 years) had a lower pooled mortality risk compared with older patients (≥60 years): 25% vs. 47% (risk ratio [RR] = 0.55; 95% CI 0.44-0.69; p<0.01).
Race also appeared to affect mortality risk, the authors reported. In five studies that included race-based outcomes, non-white patients with hematologic malignancies and COVID-19 had a higher risk of death versus white patients (RR=2.2; 95% CI 1.3-3.8; p=0.003).
Mortality risk also varied according to type of hematologic malignancy:
- acquired bone marrow failure syndromes: 53%
- acute leukemias: 41%
- plasma cell dyscrasias: 33%
- lymphomas (including chronic lymphocytic leukemia [CLL]): 32%
- lymphomas (excluding CLL): 32%
- CLL specifically: 31%
- MPNs: 34%
Pooled mortality rates did not differ significantly from other factors, such as geographic region or recent systemic anticancer therapy. “Importantly, despite a concerning risk of death, a majority of patients with hematologic malignancy and COVID-19 recover, even following recent [cancer treatment],” the authors wrote. “These data suggest that in patients who require urgent therapy for their hematologic malignancy, treatment can be delivered despite the risks of COVID-19.”
Among hospitalized patients, the pooled risk for ICU admission was 21% (as observed in 24 studies covering 2,192 patients), the pooled risk for mechanical ventilation was 17% (as observed in 21 studies covering 1,320 patients), and the pooled risk for noninvasive ventilation was 16% (as observed in 12 studies covering 373 patients).
“Our findings also suggest that when patients [with blood cancers] become infected with COVID-19, they need close monitoring and care as they may be at higher risk of deterioration than other patients.”
—Lisa Hicks, MD
“These results suggest that when patients with blood cancers are infected with COVID-19, their risk of serious outcomes is substantial,” said Dr. Hicks. “Measures to prevent infection are extremely important in this population.” These types of measures include robust use of personal protective equipment, masking, social distancing, and prioritized access to COVID-19 vaccination for patients and their care givers.
“Our findings also suggest that when patients become infected with COVID-19, they need close monitoring and care as they may be at higher risk of deterioration than other patients,” she added.
The investigators cited the significant heterogeneity in many of the pooled mortality estimates across studies as a major limitation of the meta-analysis. Dr. Hicks added that given the nature of the study’s design, the findings “should be considered hypothesis-generating, rather than definitive.”
Study authors report no relevant conflicts of interest.
Vijenthira A, Gong IY, Fox TA, et al. Outcomes of patients with hematologic malignancies and COVID-19: a systematic review and meta-analysis of 3377 patients. Blood. 2020;136(25):2881-2892.