Hematologic parameters ‘more accurate’ when diagnosing infectious mononucleosis

Hematologic parameters appeared to be “more accurate” than symptoms and signs when diagnosing infectious mononucleosis, researchers wrote in the Journal of the American Board of Family Medicine.

“The accuracy of individual symptoms, signs, and several easily obtainable hematologic parameters for diagnosing infectious mononucleosis still needs to be confirmed,” Xinyan Cai, PhD, MSPH, of the department of epidemiology and biostatistics at the University of Georgia, and colleagues wrote. “Improving the diagnosis of infectious mononucleosis based on the clinical findings could prompt physicians to identify better which patients need a diagnostic test for infectious mononucleosis.”

Cai and colleagues conducted a systematic review and meta-analysis of 17 studies. The age of participants averaged between 4 and 32 years, and between 37% to 72% of them were women or girls. The largest study included 1,000 participants. The prevalence of infectious mononucleosis among prospective cohort studies ranged from 2.1% to 80%.

Compared with a previous review, the researchers included studies that addressed lymphadenopathy, sore throat, headache and splenomegaly, allowing them “to make a more precise summary estimate of the accuracy for these symptoms and signs,” they wrote.

Cai and colleagues reported that the presence of splenomegaly (positive likelihood ratio = 2.39; 95% CI, 1.11-5.51), palatal petechiae (positive likelihood ratio, 1.32-11.4), posterior cervical lymphadenopathy (positive likelihood ratio = 3.16; 95% CI, 1.45-5.2), and axillary or inguinal cervical lymphadenopathy (positive likelihood ratio = 3.05; 95 CI, 1.85-4.7) “were moderately useful for ruling in” infectious mononucleosis. The “most helpful hematologic parameters for ruling in” disease included lymphocytes greater than 4 X10⁹ / L and greater than 40% to 50%, or atypical lymphocytes greater than 40%, the researchers added.

A combination of lymphocytes greater than 50% and atypical lymphocytes greater than 10% (positive likelihood ratio = 50.4; 95% CI, 8.43-162) was also helpful in diagnosing infectious mononucleosis, according to the researchers. However, “most of the clinical findings have limited diagnostic value in ruling out the disease when absent,” they added.

“Well-designed prospective studies are needed to investigate the role of the clinical findings and office-based tests among patients within a week of disease onset and evaluate the natural history of [infectious mononucleosis] to help clinicians better understand the course of the disease,” the researchers wrote.