Diagnostic parameters of cellular tests for Lyme borreliosis in Europe (VICTORY study): a case-control study

Background Cellular tests for Lyme borreliosis might be able to overcome major shortcomings of serological testing, such as its low sensitivity in early stages of infection. Therefore, we aimed to assess the sensitivity and specificity of three cellular tests. Methods This was a nationwide, prospective, multiple-gate case-control study done in the Netherlands. Patients with physician-confirmed Lyme borreliosis, either early localised or disseminated, were consecutively included as cases at the start of antibiotic treatment. Controls were those without Lyme borreliosis from the general population (healthy controls) and those with potentially cross-reactive conditions (eg, autoimmune disease). We used three cellular tests for Lyme borreliosis (Spirofind Revised, iSpot Lyme, and LTT-MELISA) as index tests, and standard two-tier serological testing (STTT) as a comparator. Clinical data from Lyme borreliosis patients were collected at baseline and at 12 weeks after inclusion, and blood samples were obtained at baseline, 6 weeks, and 12 weeks. Control participants underwent clinical and laboratory assessments at baseline only. Findings Cases comprised 271 patients with Lyme borreliosis (of whom 245 had early-localised Lyme borreliosis and 26 had disseminated disease) and controls comprised 228 participants without Lyme borreliosis from the general population and 41 participants with potentially cross-reactive conditions. Recruitment occurred between May 14, 2018, and March 16, 2020. The specificity of STTT in healthy controls (216 of 228 samples [94.7%, 95% CI 91.5-97.7]) was higher than that of the cellular tests: Spirofind (140 of 171 [81.9%, 76.1-87.2]), iSpot Lyme (32 of 103 [31.1%, 21.5-40.3]) and LTT-MELISA (100 of 190 [52.6%, 44.9-60.3]). Cellular tests had varying sensitivities: Spirofind (88 of 204 [43.1%, 36.4-50.4]), iSpot Lyme (51 of 94 [54.3%, 44.5-63.7]), and LTT-MELISA (66 of 218 [30.3%, 23.8-36.7]). The Spirofind and iSpot Lyme outperformed STTT for sensitivity, but were similar to the C6-ELISA (C6-ELISA: 135 of 270 [50.0%, 44.5-55.5]; STTT: 76 of 270 [28.1%, 23.0-33.6]). Interpretation The cellular tests for Lyme borreliosis used in this study have a low specificity compared with serological tests, which leads to a high number of false-positive test results. We conclude that these cellular tests are unfit for clinical use at this stage. Copyright (c) 2022 Elsevier Ltd. All rights reserved.