Mantoux reaction in patients with HIV-related pulmonary tuberculosis in Maiduguri, Nigeria

Abstract

Tuberculin skin testing is used for the identification of individuals with infection by Mycobacterium tuberculosis and other non-tuberculous mycobacteria. However, its value in immunosuppressed individuals due to human immunodeficiency virus (HIV) infection is controversial. This study was aimed at determining the relationship between Mantoux reaction and CD4+ cell counts; and whether the test can be used to predict CD4+ counts in patients dually infected with Human Immunodeficiency Virus and M. tuberculosis. Eighty patients, comprising 42 males (52.5%) and 38 females (47.5%) confirmed to be having antibodies to HIV who also had sputum smear positive pulmonary tuberculosis were recruited over a period of 16 months. They were Mantoux-tested with 0.1 ml of 5TU of PPD which was interpreted thus: <5mm = negative, =5mm = positive. CD4+ counts were determined using Dynabeads technique. The ages of all the patients ranged between 18 and 55 years (mean ± SD: 33.9±8.42 years). The males had a mean age of 35.4 ± 7.7 years while that of the females was 29.6±5.3 years (P<0.05). The CD4+ counts ranged between 73 and 512 cells/µl with a mean of 235.05 ± 112.8 cells/µl. Fifty-seven (71 %) patients had negative PPD tests while 23 (29%) tested positive. Of the 37 with CD4+ counts <CD4+counts<200cells/µl, 32(86.48%) had negative reaction (<5mm) and 5(13.51%) were positive (=5mm) as compared to those with CD4 counts =200 cells/µl, among whom 25 (58.13%) were negative and 18 (41.86%) were positive (P<0.05). The positive predictive value was low at 56.14%. The difference in mean indurations between those with CD4+ count<200cells/µl versus those with CD4+ count =200 cells/µl was statistically (P<0.05). On the whole, Mantoux indurations were noted to weakly correlate positively with CD4+ counts (Pearson's correlation, r=+0.36, P=0.00l. It was concluded that there is a weak positive correlation between Mantoux reaction and CD4+ cell counts and that the Mantoux test is a poor predictor of CD4+ cell count.