Diagnostic Performance of Hemophagocytic Lymphohistiocytosis Criteria and HScore in Critically Ill Patients With Severe Hemophagocytic Syndrome.

OBJECTIVES

To assess whether critically ill hematologic patients without diagnosis of hemophagocytic lymphohistiocytosis may have features mimicking hemophagocytic lymphohistiocytosis according to both diagnostic scores.

DESIGN

A retrospective case-control study.

SETTING

Hemophagocytic syndrome diagnosis was standardized and based on a consensual diagnosis by at least two experts of a university hospital which is a reference center for hemophagocytic syndrome.

PATIENTS

Cases (hemophagocytic syndrome+) consisted in a group of consecutive patients (n = 150) admitted in our ICU between 2007 and 2018. Control group (hemophagocytic syndrome-) consisted in patients included in a prospective multicenter cohort of hematologic patients in whom three independent experts ruled out the diagnosis of hemophagocytic syndrome (n = 1011).

MEASUREMENTS AND MAIN RESULTS

Overall, 1,161 patients were included. Hospital mortality was 45.8% in hemophagocytic syndrome- patients (n = 66) and 38.8% in control patients (n = 392; p = 0.126). Median HScore was 235 (205-262) in hemophagocytic syndrome+ and 42 (18-62) in hemophagocytic syndrome- patients (p < 0.001); number of hemophagocytic lymphohistiocytosis criteria was 4 (4-5) vs 1 (0-1), respectively (p < 0.001). Diagnostic performances of both scores were excellent with area under receiver operating characteristic curve of 0.99 (95% CI, 0.99-0.99) and 0.99 (95% CI, 0.99-0.99) for hemophagocytic lymphohistiocytosis and HScore, respectively. After propensity score matching (n = 144 × 2), the median HScore was 234 (205-262) in hemophagocytic syndrome+ patients versus 49 (18-71) in hemophagocytic syndrome- patients (p < 0.001). Median number of hemophagocytic lymphohistiocytosis criteria was 4 (4-5) in hemophagocytic syndrome+ and 1 (0-1) in hemophagocytic syndrome- patients (p < 0.001). Area under receiver operating characteristic curve was then of 0.98 (95% CI, 0.96-0.99) for hemophagocytic lymphohistiocytosis criteria and 0.99 (95% CI, 0.99-1) for HScore.

CONCLUSIONS

In ICU patients, several conditions share some similarities with hemophagocytic syndrome, explaining the poor predictive value of isolated biological markers such as ferritin level. Despite these potential confounding factors, our study suggests HScore and hemophagocytic lymphohistiocytosis criteria to be highly discriminant identifying hemophagocytic syndrome in critically ill patients.