Self-assessment of tuberculin skin test reactions by New York City firefighters: reliability and cost-effectiveness in an occupational health care setting.

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 (kappa = 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.