Two-step tuberculin testing in a veterans domiciliary population

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Occupational Health

Background:

• Tuberculin testing is crucial for tuberculosis (TB) surveillance in healthcare settings.
• The "booster phenomenon" can inflate TB infection rates in serial testing.
• Understanding boosting prevalence is key for accurate TB epidemiology.

Purpose of the Study:

• To evaluate the prevalence of the booster phenomenon in a veteran population undergoing tuberculin testing.
• To assess the impact of two-step testing on TB infection rates.
• To compare the costs of two-step testing with preventive therapy.

Main Methods:

• Employed the Mantoux test with 5 TU of purified protein derivative (PPD).
• Re-tested non-significant reactors after one week to identify the booster effect.
• Collected cost data for the testing and compared with estimated preventive therapy costs.

Main Results:

• Initial testing showed a 39.3% reaction rate; two-step testing increased this to 46.7%.
• The booster phenomenon was observed in 55 of 414 subjects (13.3%), an intermediate rate.
• Two-step testing costs marginally exceeded estimated isoniazid preventive therapy costs.

Conclusions:

• Two-step tuberculin testing effectively identifies additional reactors, likely due to the booster phenomenon.
• The booster effect prevalence in this cohort was intermediate compared to other reported studies.
• The cost-effectiveness of two-step testing warrants consideration against preventive therapy costs.