Predictors for Severe Community-Acquired Pneumonia in Patients With Hematologic Cancer

Patients with hematologic cancer (HC) were found to have an increased burden of community-acquired pneumonia (CAP), with significantly increased morbidity and mortality rates, according to results of a cohort study published in Clinical Infectious Diseases.

Investigators identified episodes of CAP among all adult patients diagnosed with HC who received care at 2 tertiary hospitals in the Netherlands between 2016 and 2019. They calculated the annual incidence rate of CAP per 100,000 patient-years of follow-up for the entire inpatient and outpatient hospital population, with results stratified by HC subtype. The investigators also compared differences in CAP rates over time between patients with HC vs the general in-hospital population, as well as the difference in CAP rates according to HC subtypes.

To identify predictors of CAP, the investigators matched patients with HC and CAP by HC subtype in a 1:1 fashion against a control group of patients with HC alone. Multivariable binary logistic regression was used to identify predictors for severe CAP.

A total of 275 patients were diagnosed with CAP within 6264 patient-years of follow-up. The rate of CAP among patients with HC was significantly increased (4390 per 100,000 patient-years) compared with the general in-hospital population (275 per 100,000 patient-years), with no significant changes noted during the study period (incidence rate ratio [IRR], 0.9; 95% CI, 0.6-1.3 vs IRR, 1.0; 95% CI, 0.9-1.2, respectively). After stratification by HC subtype, the rate of CAP was most increased among patients with acute myeloid leukemia, acute lymphoblastic leukemia, and multiple myeloma, with similar results observed among those who underwent autologous or allogenic stem cell transplantation.

The rates of hospital admission, transfer to an intensive care unit, and mortality among patients with HC and CAP were 67.4%, 9.8% and 5.5%, respectively. Of note, the rate of mortality was increased among patients with HC and CAP compared with those with HC alone (odds ratio [OR], 6.85; 95% CI, 3.83-12.25). In addition, Streptococcus pneumoniae was the most common causative agent in patients diagnosed with CAP.

The investigators noted that CURB-65 (confusion, urea nitrogen, respiratory rate, blood pressure, 65 years of age and older) scores, available for 186/275 patients, were a statistically significant predictor for severe CAP (OR, 2.19; 95% CI, 1.41-3.41). After multivariable binary logistic regression was performed, pneumococcal pneumonia, comorbid chronic obstructive pulmonary disease, neutropenia, and the use of antibacterial prophylaxis prior to CAP diagnosis also were found to be independent predictors for severe disease.

Independent risk factors for CAP in patients with HC included male sex, chronic kidney disease, hematopoietic stem cell transplantation, use of immunosuppressive drugs to treat graft vs host disease, use of rituximab and immunomodulators, and decreased lymphocyte counts and hemoglobin concentrations.

This study was limited as data were collected from only 2 tertiary hospitals, thus these findings may not be representative of the entire population of patients with HC. Other limitations included that CAP diagnoses were made on the basis of clinical and radiologic factors, therefore missed diagnoses of CAP may have occurred in patients with neutropenia.

“Based on [these findings], vaccination against respiratory pathogens such as S pneumoniae should be promoted early in the disease course of patients with HC, before starting rituximab or immunomodulators when possible, because these therapies significantly increase the risk [for] CAP,” the investigators concluded.

Reference

Certan M, Garcia Garrido HM, Wong G, Heijmans J, Grobusch MP, Goorhuis A. Incidence and predictors of community-acquired pneumonia in patients with hematological cancers between 2016 and 2019. Clin Infect Dis. Published online February 23, 2022. doi:10.1093/cid/ciac005