Dried tube specimens: A tool to ensure effective proficiency testing & quality control of Hepatitis B virus diagnosis in developing countries

Abstract

Background: Proficiency testing (PT) is a key component of Quality assurance to evaluate the laboratory performance. Although HBV testing has rapidly expanded worldwide, but in resource limited settings (RLS) like India there is still a lacunae in PT programs to monitor and improve the quality of testing. Conventional PT programs use serum or plasma specimens that require strict settings for storage and transportation. Thus the aim was to standardize dried tube specimens (DTS) technique for stability studies of HBV specimens as has been done for PT programs in HIV-EQAS. Methods: Dried tube specimens, an unusual, simple and easy to use technique, were standardized that can help assessing the quality of Hepatitis B Surface Antigen (HBsAg) testing in RLS. DTS were prepared by drying 30l of samples mixed with 0.1% of green dye, left overnight at room temperature. The DTS were rehydrated with 250l of PBSTween buffer before testing. Twenty DTS samples (09 HBV positive and 11 negative) were used for performing ELISA and rapid tests at weekly interval for Dried tube specimens stored at 4C, 25C, 37C & 45C. Results: Stability studies showed that HBsAg in the DTS specimens were stable upto 28 days at temperature 4C, 25C, 37C & 45C. We observed consistent and expected results for all the DTS samples by ELISA and rapid tests for the different durations and temperatures. No difference in the qualitative nature of the HBV reactive and non-reactive samples were observed for Dried tube specimens over 28 days duration and stored at 4C, 25C, 37C & 45C temperatures. However, a decline in HBsAg levels were observed after four weeks (28days) for a few specimens stored at 45C. Conclusion: Stability results of this preliminary study indicate that the reactivity status was unchanged and maintained for HBV plasma samples upto 28 days at temperatures (4C, 25C 37C& 45C) in the dried tube specimens. Further we found DTS is an easy and simple method to prepare and transport quality control specimens for effective implementation of PT programs to monitor HBV testing in India.