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Tuberculin testing in a tertiary hospital: product variability
J W Shands1, D Boeff, L Fauerbach
1University of Florida College of Medicine, Gainesville 32610.
Infection Control and Hospital Epidemiology
|December 1, 1994
Summary
A study found that 9% of hospital employees tested positive for tuberculosis using Aplisol. Retesting revealed 70% of these results were false positives, indicating excessive potency and wasted resources investigating a nonexistent outbreak.
Area of Science:
- Public Health
- Infectious Disease Epidemiology
- Diagnostic Accuracy
Background:
- Tuberculosis screening is crucial in healthcare settings.
- Accurate diagnostic tests are essential for effective public health surveillance.
- Previous tuberculin skin test (TST) reagents have varying potencies.
Purpose of the Study:
- To evaluate the accuracy of a specific tuberculin PPD reagent (Aplisol).
- To assess the impact of reagent potency on tuberculosis screening outcomes in hospital employees.
- To determine the rate of false-positive results and their economic consequences.
Main Methods:
- A cohort of 2,721 tuberculin-negative hospital employees underwent TST using 5 TU of PPD (Aplisol).
- Positive reactions were retested using a different PPD reagent (Tubersol).
- False-positive rates and associated resource expenditure were analyzed.
Main Results:
- Nine percent (245/2721) of employees initially tested positive with Aplisol.
- Seventy percent (171/245) of these positive reactions were identified as false positives upon retesting with Tubersol.
- The high false-positive rate led to unnecessary investigations and resource allocation.
Conclusions:
- The PPD reagent Aplisol demonstrated excessive potency, leading to a high rate of false-positive tuberculosis screening results.
- This inaccuracy resulted in significant wasted time and financial resources for the hospital.
- Ensuring reagent standardization and accuracy is vital for reliable tuberculosis surveillance and preventing unnecessary public health responses.