Validity of a point-of-care test based on heterophile antibody detection for the diagnosis of infectious mononucleosis in primary care

Objective: To evaluate the validity of a point-of-care test to diagnose infectious mononucleosis (IM) compared with Epstein -Barr virus (EBV) specifi c serology. Methods: Patients over 14 years with sore throat and four Centor criteria-tonsillar exudate, fever, lymph glands tenderness and absence of cough-and negative pharyngeal testing for group A beta-haemolytic streptococcal antigen were consecutively recruited. All patients underwent pharyngotonsillar swab for microbiological culture, the rapid OSOM MonoTest for the diagnosis of IM in whole blood, the Paul-Bunnell test and complete blood analysis with serology for EBV and cytomegalovirus the day after the visit and at 15 days. Sensitivity and specifi city were determined. Results: We included 145 patients with a mean age of 24 +/- 6.8 years. Of these, serology was determined in 129 subjects, with IM being diagnosed in 14 (10.9%). Both the MonoTest and the Paul-Bunnell test were positive in 13 patients with IM (92.9%) with no patient without disease being positive for either test-sensitivity of 92.9% (95% Cl: 64.2-99.6%) and specifi city of 100% (95% Cl: 96-100%). The culture showed streptococcus A infection in 1 case (0.7%) and streptococcus C in 62 cases (42.8%). A total of 78 patients presented past infection by EBV (60.5%). Conclusion: Only one out of 10 patients with sore throat, four Centor criteria and negative rapid test for streptococcal infection presents IM. Despite the MonoTest presenting optimum sensitivity and specifi city, it was found to have the same validity as the Paul-Bunnell test, with serological study continuing to be necessary for precise diagnosis of IM.