Rapid tests for diagnosing syphilis: Validation in an STD clinic in the Amazon Region, Brazil

Abstract

Correct, early diagnosis and treatment of syphilis are essential for its control. Traditional diagnostic tests depend on specialized equipment, installations, and human resources. In the search for quick, simple tests, a project was conducted on the validation and reproducibility of four different tests, previously assessed by WHO reference laboratories. The study also verified the operational characteristics and acceptance by patients and health professionals. Samples obtained at an STD clinic were from 541 and 248 patients with 51 and 52 positive results according to FTA-Abs (gold standard) in studies 1 and 2, respectively. The sensitivity varied from 84 to 96%, specificity was greater than 98%, and PPV was > 90%. Reproducibility was > 97% and kappa index 0.94, comparing the results obtained by different health workers. The tests took less than 20 minutes to perform, and more than 90% of patients agreed to wait up to two hours for the results. The tests presented the necessary requirements for use in diagnosis of syphilis, thus providing an additional option for controlling this disease.