COST EFFECTIVENESS OF STRATEGIES FOR DIAGNOSIS OF HEPATITIS C IN MEXICO

Purpose: To undertake a cost-effectiveness analysis of different alternatives to diagnose hepatitis C virus. The alternatives use the antibody test (anti-HCV) (chemiluminescence assay) in combination with confirmatory testing. We want to evaluate whether a new classification of results based on the signal-to-cut-off (S/CO) ratio in three levels (very low, low and high), in combination with recombinant immunoblot assay (RIBA) and RNA HCV testing, is more cost-effective than conventional alternatives. 

Method: We used a decision tree model to evaluate five alternatives of diagnosis, considering the percentage of viremic cases as the main outcome of the analysis. We used data from previous published studies on the sensitivity and specificity of combination of the anti-HCV, RIBA and RNA HCV tested in 649 blood donors.  The alternatives were defined by combination of three different classifications of anti-HCV, RIBA and RNA HCV. The classifications of the anti-HCV based on the S/CO ratio values were as follows: 1) Three-levels: very low 1-4.99, low 4.5-19.99 and high ≥20. 2) Two-levels: low ≤8 and high >8 and 3) positive ≥1. The five alternatives were defined as follows: A1) Three level anti-HCV -> RIBA or RNA HCV1 (No RIBA or RNA HCV if anti-HCV is very low) A2) Three level anti-HCV -> RIBA or RNA HCV2 (Yes RIBA or RNA HCV if anti-HCV is very low) A3) Two level anti-HCV ->RIBA or RNA HCV2 A4) Anti-HCV ≥1 -> RIBA -> RNA HCV A5) Anti-HCV ≥1 -> RNA HCV -> RIBA

Result: The alternative A1 was dominant (strong) compared with the A2-A4 alternatives in base- case scenario of low hepatitis C prevalence (<1%). In the scenario for intermediate prevalence (1-9.5%) A1 was the most cost effective but A5 was dominated (extended) by A4. High scenario prevalence showed similar results of those in low prevalence.

Conclusion: Our results suggest that the use of the three-levels classification of the anti-HCV results and no testing when level is very low can be more cost-effective than the other alternatives considered in our analysis. Health providers can benefit from diagnosis of HCV from reduction of costs with the use of strategy A1in patients with low probability of being viremic who are not considered for further testing. Probabilistic sensitivity analysis and discussion are under development.