Conversion and reversion of tuberculin reactions in nursing home residents

Abstract

To assess the consistency of tuberculin reactions over time, we performed tuberculin tests in a cohort of 495 nursing home residents in both 1982 and 1985. Significant reactions (greater than or equal to 10 mm of induration to 5 TU PPD) were found in 258 (52.1%) and 209 (42.2%) residents in 1982 and 1985, respectively. Males, nonwhites, and persons younger than 80 yr of age had a greater proportion of significant reactions (all, p less than 0.01). Of the 237 persons with nonsignificant reactions in 1982, 15 (6.3%) had a significant reaction in 1985. None of the 15 converters was found to have current tuberculosis. Tuberculin reversions occurred in 64 (24.8%) of 258 persons who had significant reactions in 1982. Of the patients who had a significant reaction only after boosting in 1982, 16 of 21 (76.2%) had nonsignificant reactions with up to 3 tests in 1985. Tuberculin reactions in nursing home residents may vary over time and may not be recalled by boosting, boosted reactions may be transient, and apparent conversions may be due to an extension of the booster phenomenon.