Validity of a self-reported history of a positive tuberculin skin test. A prospective study of drug users.

Objective: To define the prevalence of and factors associated with having a negative purified protein derivative (PPD) among persons who self-report a prior positive PPD and to define the safety of repeat testing in such persons.Design: Observational cohort study.Setting: Methadone maintenance program with onsite primary care.Patients/participants: Current or former drug users enrolled in methadone maintenance treatment.Interventions: Structured interview, tuberculin skin testing regardless of self-reported PPD status, and anergy testing.Measurements and Main Results: Nearly one third (31%) of participants who self-reported a prior positive PPD had a negative measured PPD, despite receipt of a "booster" PPD. A single participant (0.5%) blistered in response to the PPD without lasting ill effect. Participants with PPD results discordant from their history were more likely to be HIV-seropositive and nonreactive to the anergy panel. The discordance rate among HIV-infected participants was 43%, and was largely attributable to immune dysfunction. Among HIV-seronegative participants, the discordance rate was 27%. Recent crack-cocaine use was independently associated with discordance in the absence of HIV infection.Conclusions: We confirmed that planting a PPD in patients who self-report a positive PPD history confers minimal risk. Substantial rates of discordance exist between self-reported history of a positive PPD and measured PPD status. Further research is needed to define the optimal management of PPD-negative patients who self-report a prior positive PPD and who have not received prior treatment for latent tuberculosis. [ABSTRACT FROM AUTHOR]

Copyright of JGIM: Journal of General Internal Medicine is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)