DISCUSSION
The current study was conducted for the evaluation and performance of
diagnostic accuracy of GeneXpert MTB/RIF in detection of TB. The results
of GeneXpert were also compared with other diagnostic methodologies
including MGIT culture method and ZN staining method.
Out of the total 716 clinically TB suspects, 48.6% (N = 348)
individuals were confirmed as positive for TB. The prevalence of TB
positive individuals was higher in the middle age group individuals.
The characteristics of the clinically TB suspects between the TB
positive and TB negative groups were similar except from smoking status.
Smoking status in TB positive group individuals was significantly higher
(27.3%) than TB negative group individuals (20.9%). Age and gender of
the individuals between the groups did not differ significantly.
GeneXpert results were accurate and reliable with the sensitivity of
99.7% and specificity of 97.3%. The positive predictive value and
negative predictive values were comparatively higher 97.1% and 99.7%
respectively in GeneXpert result analysis. The chances of tested as
being false positive and false negative were also as low as 2.7% and
0.3% respectively. The results of current study are in line with
previous studies conducted for the performance of GeneXpert diagnostic
method [9, 10].
Although the difference was not statistically significant, the disease
was comparatively more prevalent in females than males. The reason for
high prevalence in female gender might be inaccessibility to health care
facilities. Women often face hindrances in gaining approach to
diagnostic services, health examinations and in completing sufficient
treatment. Furthermore, the burden of household assignments and
childcare leave them with meager time to access health care and
particularly tuberculosis care for themselves [15].
Smoking is an independent risk factor not only for active TB but also
for latent TB cases. Smoking significantly increase the risk of
acquiring and development of TB. According to study results, smoking
status of individual was statistically significantly different between
TB positive and TB negative groups. Higher rates were observed in TB
positive individuals. We did not have information about passive smoking
that could have explained the results further. Non-smoking individuals
are easily exposed to passive smoking especially in the current study
population as smoking indoor and in public places is not very rare event
[16-18].
The strength of the present study is the large sample size and
comparison with conventional TB diagnosis methodologies. Along with
performance of GeneXpert techniques, we also performed comparative
analysis between different available diagnostic techniques including ZN
staining and MGIT culture. We also collected different socioeconomic
parameters of study individuals that help in exploring the trends.
The limitations of our study included no information of human
immunodeficiency viruses (HIV), hepatitis B virus (HBV) and hepatitis C
virus (HCV). Although HIV is not very common in the study population but
the prevalence of HBV and HCV is higher in the study population
[18].