Accuracy of Signs, Symptoms, and Hematologic Parameters for the Diagnosis of Infectious Mononucleosis: A Systematic Review and Meta-Analysis.

Background: The accuracy of individual symptoms, signs, and several easily obtainable hematologic parameters for diagnosing infectious mononucleosis (IM) still needs to be confirmed. Improving the diagnosis of IM based on the clinical findings could prompt physicians to identify better which patients need a diagnostic test for IM. This study performed a systematic review to determine the accuracy of symptoms, signs, and hematologic parameters in patients with suspected IM that used heterophile antibody test or viral capsid antigen tests as the reference standard. Methods: The PubMed database was searched for all relevant articles. Two reviewers reviewed all studies in parallel and assessed the quality of the selected studies using the quality assessment of diagnostic accuracy studies 2 (QUADAS-2) criteria. The pooled measures of diagnostic performance were calculated by bivariate meta-analysis for each clinical finding, which included sensitivity, specificity, likelihood ratios, the diagnostic odds ratios, and the area under the receiver operating characteristic curve. Results: Seventeen studies were included in our final analysis. The prevalence of IM ranged from 2.1% to 80% among prospective cohort studies. The presence of splenomegaly (positive likelihood ratio [LR+], 2.39; 95% confidence interval [CI], 1.11-5.51), palatal petechiae (LR+, 1.32-11.40), posterior cervical lymphadenopathy (LR+, 3.16; 95% CI, 1.45-5.20), and axillary or inguinal cervical lymphadenopathy (LR+, 3.05; 95 CI, 1.85-4.70) were moderately useful for ruling in IM. The most helpful hematologic parameters for ruling in IM include lymphocytes greater than 4 × 109/L and greater than 40% to 50%, or atypical lymphocytes greater than 40%. A combination of lymphocytes greater than 50% and atypical lymphocytes greater than 10% (LR+, 50.40; 95% CI, 8.43-162) was also found to be helpful to rule in disease. Most of the clinical findings have limited diagnostic value in ruling out the disease when absent. Conclusions: Although most symptoms and signs were unhelpful, the likelihood of IM is appreciably increased by several examination findings. Hematologic parameters were more accurate than symptoms and signs. Since most clinical findings have limited diagnostic value in ruling out the disease, physicians should not rely on the absence of any individual symptom or clinical sign for ruling out IM.