Lymphopenic Community Acquired Pneumonia (L-CAP), an Immunological Phenotype Associated with Higher Risk of Mortality.

The role of neutrophil and lymphocyte counts in blood as prognosis predictors in Community Acquired Pneumonia (CAP) has not been adequately studied. This was a derivation-validation retrospective study in hospitalized patients with CAP and no prior immunosuppression. We evaluated by multivariate analysis the association between neutrophil and lymphocyte counts and mortality risk at 30-days post hospital admission in these patients. The derivation cohort (n=1550 patients) was recruited in a multi-site study. The validation cohort (n=2846 patients) was recruited in a single-site study. In the derivation cohort, a sub-group of lymphopenic patients, those with <724lymphocytes/mm, showed a 1.93-fold increment in the risk of mortality, independently of the CURB-65 score, critical illness, and receiving an appropriate antibiotic treatment. In the validation cohort, patients with <724lymphocytes/mm showed a 1.86-fold increment in the risk of mortality. The addition of 1 point to the CURB-65 score in those patients with <724lymphocytes/mm improved the performance of this score to identify non-survivors in both cohorts. In conclusion, lymphopenic CAP constitutes a particular immunological phenotype of the disease which is associated with an increased risk of mortality. Assessing lymphocyte counts could contribute to personalized clinical management in CAP.