Correlation of sputum smear status with CD4 count in cases of pulmonary tuberculosis and HIV co-infected patients--a hospital based study in a rural area of Central India.

BACKGROUND

In HIV-infected patients, PTB (Pulmonary Tuberculosis) is still the commonest form of TB. The most cost-effective method of detecting TB cases among PTB suspects in high-prevalence countries is by sputum smear microscopy. World Health Organisation (WHO) states that sputum positivity decreases accompanying with atypical chest x-ray findings as CD4 count decreases. This expectation that infection with HIV would reduce the sensitivity of acid-fast smears, due to a decreased frequency of cavitary pulmonary MTB, has not been substantiated in a few studies done in the past. This study was undertaken to see the correlation of sputum smear status with CD4 count in cases of Pulmonary Tuberculosis HIV coinfected patients in our institute, being a tertiary referral centre.

METHODOLOGY

In our hospital based cross-sectional study, 98 patients having PTB-HIV co-infection were followed and acid fast smear positivity status was assessed in correlation with chest radiograph and CD4 count.

RESULTS

Acid-fast smear positivity to negativity was almost 1:1 in CD4 count between 0-200 whereas it was 3:1 in cases of CD4 count above 200. There was significant difference (p value 0.013) in two groups with CD4 count cut-off value 200 which endorses the fact by WHO that sputum smear negativity increases with increase in degree of immunosupression.

CONCLUSION

Sputum examination remains an important diagnostic tool for pulmonary tuberculosis in immunocompromised host with CD4 count above 200 but there is an urgent need for better diagnostic methods in CD4 count below 200.