Does a high white blood cell count drive away the suspicion of dengue? Contributions to the diagnostic algorithm

Abstract

Objective: To evaluate the value of leukocyte count in patients with suspected dengue as a predictor of absence of disease at the initial contact with the health system.

Methods: Retrospective cohort analytical and diagnostic test study, which included all patients treated at Hospital Italiano de Buenos Aires between EW 1/2015 and 7/2016 with suspected dengue, complete laboratory monitoring and WBC in the EW of epidemiological reporting.

Results: During the study period 352 patients with suspected dengue were treated. We included 180 patients who completed follow-up (58 confirmed dengue and 122 discarded dengue). Median age 37 years (IQR 28-47.5), male 51.1% (95% CI 44-58). Among those with confirmed dengue, 46.6% (95% CI 33-60) were autochthonous cases. The predominant serotype was DEN-1. In 43/45 patients with an initial WBC ≥ 9000 diagnosis of dengue was discarded. The negative predictive value of this cut-off point is 95.5% (95% CI 84.9-99.5).

Conclusions: To add a leukocyte count ≥9000 as a criterion to the existing algorithms, in order to reduce the suspicion of dengue at the time of the initial contact, could significantly improve their negative predictive value . Only 1 in 20 patients with a WBC ≥ 9000 during the first contact with the health system in this context has a confirmed diagnosis of dengue.