The laboratory impact of changing syphilis screening from the rapid-plasma reagin to a treponemal enzyme immunoassay: a case-study from the Greater Toronto Area.

BACKGROUND: In 2005, syphilis screening in the Greater Toronto Area of Canada moved from the rapid plasma reagin (RPR) to a treponemal enzyme immunoassay (EIA). We sought to understand the consequences of this change on laboratory results and testing patterns with a population-based retrospective study of laboratory-based diagnoses of syphilis. METHODS: Samples positive under RPR (1998-2005) and EIA (2005-2008) screening were confirmed with an alternate treponemal test, and during the latter period underwent RPR testing. We compared monthly rates and the forecasting relationship between positives and future submissions with time-series methods, and assessed risk factors for EIA(+)/RPR(-) results using Poisson regression. RESULTS: A total of 3,092,938 submissions were included. Following EIA implementation, confirmed positive rates increased by 10.3 per 100,000 population (P<0.001). 0.59% of EIA(+)/RPR(-) individuals converted to RPR(+) within 2 months. EIA(+)/RPR(-) patients were more likely to be male (incidence rate ratio [IRR]: 2.3, 95% confidence interval [CI]: 1.6-2.5), asymptomatic (IRR: 1.8, 95% CI: 1.3-2.8), and aged>50 years (IRR: 2.4, 95% CI: 1.6-3.5) than those with EIA(+)/RPR(+) results. We detected a significant positive feedback loop between positive tests and subsequent submissions. This relationship was only transiently evident for EIA(+)/RPR(-) results up to 1 year following the changeover. CONCLUSIONS: EIA screening facilitates identification of probable latent syphilis and earlier serological detection of infectious syphilis, but may transiently cause increases in testing and indirectly suggests that physicians' interpretation of RPR(-) serology may lead to partner testing. In the absence of a true gold standard, implementation of EIA screening warrants careful communication regarding serological interpretation.

CYP450, COX-2 and Obesity Related Renal Damage.

Abstract The number of obese people in the world is growing rapidly worldwide and has reached epidemic status. Obesity is often associated with the clustering of metabolic and cardiovascular risk factors that contribute to metabolic syndrome or syndrome X. Likewise, metabolic syndrome and its associated traits are major contributing factors to the increase in nephropathy and end stage renal disease. The specific factors that link the metabolic syndrome traits to the progression of nephropathy remain largely unexplored. Recent studies have demonstrated that an imbalance between cyclooxygenase-2 (COX-2) and cytochrome P450 (CYP450) arachidonic acid metabolizing enzymes in the kidney may contribute to the renal damage associated with obesity. Along these lines, COX-2 inhibition decreases renal cytokine levels and glomerular injury in obese rats. Peroxisome proliferators-activated receptors (PPARs) are transcription factors that also contribute to chronic kidney disease in obesity and metabolic syndrome. Intriguingly, interactions between PPARs and arachidonic acid metabolites could be key determinants of renal damage in metabolic syndrome patients. Therefore, there is a promising future for pharmacological agents that manipulate COX-2 and CYP450 metabolites and PPARs to treat obesity related nephropathy.