Objective: To determine whether self-assessment of purified protein derivative of tuberculin (PPD) skin test reactions, done using a simple two-choice approach, is an effective screening method for tuberculosis.
Design: Double-blind comparison between self-assessments and trained professional readings of PPD skin test reactions, done 72 hours after test administration.
Setting: The New York City Fire Department's Bureau of Health Services
Participants: 2011 New York City firefighters and fire officers were given PPD skin tests during a mandatory retraining course. Thirty-seven persons were excluded because of a history of a positive PPD skin test result or a bacille Calmette–Guérin vaccination. All others agreed to participate in testing and self-assessment done using simple written instructions. Self-assessment results were submitted just before trained professional readings were done.
Measurements: Self-assessments and trained professional readings of PPD skin test reactions.
Results: 1833 participants (91%) interpreted their test reactions as flat. Of these interpretations, 1824 (99.5%) matched the professional reading and 9 (0.5%) did not. One hundred seventy-eight participants (9%) interpreted their test reactions as not flat; 136 of these interpretations (76.4%) matched the professional reading and 42 (23.6%) did not (κ = 0.828; lower 95% confidence limit = 0.790). The predictive value of a negative self-assessment reading was 99.5%, and the specificity was 97.7%.
Conclusion: In this occupational health care setting, we follow (and recommend to others with similar populations) a tuberculin screening program based on self-assessment. Repeated tests with follow-up are required for all persons who do not report their results. All persons with self-assessments of “not flat” should return for readings by trained professionals, counseling, and treatment.