High laboratory cost predicted per tuberculosis case diagnosed with increased case finding without a triage strategy

Area of Science:

• Public Health
• Health Economics
• Infectious Disease Diagnostics

Background:

• Tuberculosis (TB) diagnosis relies on laboratory testing, with costs influenced by case-finding and triage strategies.
• The GeneXpert (Xpert) system offers rapid TB diagnosis but its cost-effectiveness is debated.
• Optimizing laboratory costs is crucial for sustainable TB control programs.

Purpose of the Study:

• To model the impact of enhanced case finding and triage on laboratory costs per diagnosed tuberculosis case.
• To evaluate the cost-effectiveness of Xpert-based versus smear/culture-based TB diagnostic algorithms under varying conditions.

Main Methods:

• Utilized a validated operational model and published laboratory cost data.
• Modeled the effect of varying TB prevalence among presumptive cases and Xpert cartridge prices.
• Compared cost per TB case and per additional TB case diagnosed between Xpert and smear/culture algorithms.

Main Results:

• Increased case finding (18.3% TB prevalence) raised cost per TB case by 142% (US$121 vs. US$50) and cost per additional case to US$986.
• Lower TB prevalence (10.6%) would increase cost per additional case to US$1619.
• At 25.9-30.8% TB prevalence and 50% Xpert price reduction, costs per TB case diagnosed ranged from US$50-US$59, comparable to smear/culture.

Conclusions:

• Increased case finding significantly impacts laboratory costs per tuberculosis case diagnosed.
• The current approach is unsustainable without effective triage strategies, despite potential Xpert cartridge price reductions.
• Identifying efficient triage is essential for the economic viability of enhanced TB diagnostic strategies.