Detecting antibodies to hepatitis c in injecting drug users: A comparative Study between saliva, serum, and dried blood spot tests

摘要

BACKGROUND: Injecting drug use is associated with high rates of hepatitis C. This has been attributed to the sharing of equipment used in injecting. Testing for hepatitis C viral (HCV) infection using routine blood has proved to be problematic, and hence the need to develop alternative methods of HCV testing has arisen. OBJECTIVES: To study the utility of saliva for HCV antibody testing in comparison with the use of blood obtained by routine blood sampling or using the dried blood spot (DBS) test in the context of a randomized controlled trial of the effectiveness of primary prevention of hepatitis C in injecting drug users (IDUs). METHODS: IDUs attending drug services were screened for HCV antibodies using saliva or blood including DBS. RESULTS: There was poor acceptability of a routine blood test for HCV. Introducing the DBS was associated with a 4.6-fold increase in HCV testing. A total of 241 unique patients provided 323 DBS and/or saliva samples. The prevalence of HCV antibodies ranged from 19.7% to 52.9% (mean 26.8%) in IDUs. The prevalence of HCV infection detected by saliva was 28.5% compared with 27.6% detected by blood (DBS). In 51 IDUs who were HCV seronegative and were tested for a second time by DBS, 4 were antibody positive indicating an incidence of 8 per 100 person-years. CONCLUSIONS: Testing for HCV infection using saliva although feasible has lower sensitivity (90.4%) and lower specificity (95.1%) compared with blood samples including DBS. This study introduced the DBS to screen for HCV in clinical settings. The use of DBS removes a key obstacle for testing for HCV and is recommended for routine use in health settings and for large-scale community-based surveys of the prevalence and incidence of HCV in drug users.