Kiely P, et al. – In order to ascertain whether indeterminate results representing past exposure to hepatitis C virus (HCV) could be distinguished from those due to non–specific reactivity, results for blood donors tested on the MP Diagnostics HCV Blot 3.0 immunoblot (IB) assay were tested. Particularly in the presence of putative risk factors for HCV infection, PRISM chemiluminescent immunoassay (ChLIA) s/co ratios >2·00 with IB indeterminate results predicted exposure to HCV. Study outcomes could be applied to optimizing counselling of donors with indeterminate HCV results.

Methods

• This work entailed results for all donors tested by IB during the study period (July 2010 to December 2013).

Results

• 34 (26.0%) were negative, 38 (29.0%) were indeterminate, and 59 (45.0%) were positive, among 131 donors tested by IB.
• No significant difference was noticed in IB band reactivity strength between indeterminate and positive donors.
• As per results, the PRISM HCV chemiluminescent immunoassay (ChLIA) sample to cut-off (s/co) ratio distribution for the indeterminate donors was significantly higher than for those with biological false reactivity (P = 0·037).
• However, it was significantly lower than for donors who were IB positive/HCV RNA negative (P < 0·001) or IB not tested/HCV RNA positive (P < 0·001).
• 53.1% of the indeterminate group disclosed a putative risk factor for HCV infection compared to 39.4% (P < 0·001) for the IB-negative group, 76.6% (P = 0·065) for the IB-positive group and 83.4% (P < 0·001) for the HCV RNA-positive group, among the donors available for follow-up.