October 15, 2012 — A new meta-analysis demonstrates that point-of-care tests (POCTs) for the diagnosis of hepatitis C (HCV) have a high level of accuracy and may help increase screening rates for this disease. These findings are published in the October 15 issue of the Annals of Internal Medicine.
The study, led by Sushmita Shivkumar, MSc, from McGill University and McGill University Health Centre, Montreal, Quebec, Canada, reviewed 19 studies that evaluated the diagnostic accuracy of POCTs and rapid diagnostic tests (RDTs) that screen for HCV in oral fluid, whole blood, serum, or plasma. The researchers found that POCTs had the highest sensitivity (whole blood, 98.9% [95% confidence interval (CI), 94.5% - 99.8%] and serum or plasma, 98.9% [95% CI, 96.8% - 99.6%]). RDTs of serum or plasma had the next-highest sensitivity (98.4%; 95% CI, 88.9% - 99.8%), followed by POCTs of oral fluid (97.1%; 95% CI, 94.7% - 98.4%).
Specificity of POCTs of whole blood and serum or plasma was also high, at 99.5% (95% CI, 97.5% - 99.9%) and 99.7% (95% CI, 99.3% - 99.9%), respectively. The specificity of RDTs of serum or plasma followed, at 98.6% (95% CI, 94.9% - 99.6%), and then the specificity of POCTs of oral fluid, at 98.2% (95% CI, 92.2% - 99.6%).
"Although both diagnostic test types are rapid, RDTs require special equipment, such as centrifuges and refrigerators, whereas POCTs eliminate the need for electricity and are more robust at high temperatures, thus offering additional opportunities to expand screening," the study authors note.
The researchers evaluated studies conducted between 1992 and 2012 that screened for HCV in adults (≥18 years of age), regardless of risk profile and across all study designs. Studies on prevalence, those missing relevant information, manufacturer reports, and studies of the accuracy of laboratory-based tests were excluded.
The authors acknowledge possible study limitations, such as detection and sampling bias of the original studies as well as the influence of variable reference standards used in different studies. These differences may have had an effect on sensitivity and specificity estimates. In addition, coinfection status may alter the rate of false-positive results because of differences in the immune response and should be considered when interpreting test results. The study authors postulate that standardized reference standards and stratification by coinfection should be considered for future diagnostic accuracy studies.
Because the tests evaluated in this meta-analysis detected antibodies to HCV, the study authors note that these POCTs could not differentiate between acute and chronic infections and could not detect infection within 3 months of exposure. Cases with possible false-negative or false-positive results would require further screening, which may depend on available resources.
"Given the convenience of POCTs and their rapid turnaround time, these results show great potential for expanded ﬁrst-line screening for hepatitis C infection and demonstrate the utility of blood-based singleton POCTs and of multiplex POCTs designed to provide integrated HIV and HCV screening of at-risk populations," the study authors conclude.
Funding for this study was provided by the Canadian Institutes of Health Research. One coauthor has received additional support from Grand Challenges Canada and the Bill and Melinda Gates Foundation. The remaining authors have disclosed no relevant financial relationships.
Ann Intern Med. 2012;157:558-566. Abstract
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