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A Journal on Diseases of the Respiratory System

Official Journal of the Italian Society of Thoracic Endoscopy
Indexed/Abstracted in: EMBASE, Scopus, Emerging Sources Citation Index




Minerva Pneumologica 2008 December;47(4):159-64

language: English

Evaluation of time to sputum conversion in patients with smear positive pulmonary tuberculosis. A prospective cross sectional study

Soudbakhsh A. 1, Ahmadinejad Z. 1, Systani M. 2

1 Departments of Infectious Diseases Imamkhomeini Hospital Tehran University of Medical Sciences, Tehran, Iran
2 Infectious diseases specialist


Aim. There are several factors influencing the time to sputum conversion. These factors could be different according to the epidemiological situation of patients. The aim of this study was to determine the time to sputum conversion in patients with active new pulmonary tuberculosis. In addition authors investigated predictors for time to sputum smear conversion.
Methods. Two hundred and seventeen new tuberculosis cases, who referred to an educational referral hospital and an outpatient tuberculosis clinic in Tehran in 2005 and 2006, were studied in a cross-sectional research. Diagnosis of tuberculosis was made according to World Health Organization criteria. The significance of the difference was determined using c2 or Fisher’s exact test. For the study only data with a confidence interval of 95% were taken in consideration, while the P<0.05 was assumed significant.
Results. Sputum conversion occurred in 185 (85.3%) patients after four months from the beginning of therapy. In the study population considered, nationality, the bacilli load and the presence of cavities on a chest roentgenogram significantly influenced sputum conversion time. Smoking seems also to play a role in sputum conversion time, though it is not statistically significant (P value=0.052).
Conclusion. Considering the results of this study, nationality, the bacilli load and the cavitary disease evident on a chest roentgenogram have significant influence on sputum conversion time. Cigarette smoking can be considered as a potential effective factor, so stop smoking could be recommended in all patients with sputum smear positive tuberculosis.

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