Evidence-based diagnosis of Lyme disease

The aim of this study was to make an evidence-based comparison of four comm ercial enzyme immunoassays (EIAs) (Serion Classics, Sigma Diagnostics, Camb ridge Biotech and ICN Diagnostics) and an in-house enzyme immunoassay (EIA) in order to select the most appropriate screening assay for diagnosis of L yme disease. Borrelia burgdorferi sensu stricto cultured in BSK-H medium wa s used to develop the in-house assay. Escherichia coli antigen (0.9 mg/ml) was included in the serum diluent to reduce non-specific background. Compar ison of the number of tests needed to diagnose (i.e. to indicate a positive result) and the cost per positive diagnosis for the five assays was made u sing a panel of 176 Western blot-characterised sera. The Cambridge Biotech and Sigma assays had the highest sensitivity but poorer specificity, wherea s the Serion and ICN assays had highest specificity but poorer sensitivity. The in-house assay had average sensitivity and specificity, the number of tests needed to diagnose being 2.32 compared to 1.92 for Serion, 2.17 for I CN, 2.5 for Sigma and 2.7 for Cambridge Biotech. In a diagnostic protocol t hat uses an EIA as screening test, with confirmation by Western blot, a goo d balance of sensitivity and specificity is essential. The in-house assay w as the most cost-effective (lowest cost per positive diagnosis), and is pro bably the best option for specialist laboratories in Europe.