Tuberculosis Case Detection in Selected Health Facilities in Greater Accra Region, Ghana: Two Years after the Introduction of Genexpert Mtb/Rif Assay

Abstract

Introduction: In resource-limited settings like Ghana, conventional smear microscopy with low specificity and sensitivity is the most commonly used diagnostic tool for detection of tuberculosis (TB). The Ghana 2013 TB Prevalence Survey findings indicated that TB is four times higher compared to previous World Health Organization (WHO) estimated number and the proportion of smear negative and culture positive pulmonary TB was higher than the routine report. The increment in prevalence survey results were mainly due to the use of advanced diagnostic tests. In some selected districts with high HIV burden in Ghana, an advanced TB diagnostics test has replaced the conventional and routine sputum smear microscopy for diagnosing TB. Improving TB detection rates and further reducing the burden of disease in Ghana will require evaluation and optimization of new diagnostic technologies. Objective: The purpose of this study was to investigate the level of Tuberculosis case detection by GeneXpert MTB/RIF diagnostic test in selected public health facilities in the Greater Accra region, one year following the introduction of GeneXpert MTB/RIF assay test. Method: A retrospective study was undertaken in the Kaneshie Polyclinic, Korle Bu Teaching Hospital, La General Hospital and Ridge Regional Hospital all located in the Greater Accra region. Tuberculosis diagnostic data on all presumptive TB patients registered at the facility laboratory from January 2012 to December 2018 were extracted from Microscopy and GeneXpert MTB/RIF registers. Variables of interest included dates specimen were received and result reported, age, sex and area of residence, referral facility, specimen type, specimen quality, diagnosis results, and type of diagnostic test used. Positive TB cases detected using 5 years Smear Microscopy data was compared with two years data using GeneXpert MTB/RIF using two-sample test of proportions. Pearson Chi-square and logistic regression were used to determine factors associated with positive TB case and strength of association. Results: On the whole, the proportion of TB cases detected using Smear Microscopy was 13.1% (3,464/26,544, 95% CI: 12.6 – 13.4) and 15.1% (1301/8,595, 95% CI: 14.4 – 15.9) using the GeneXpert MTB/RIF assay test with statistically significant difference (- 2.9%, 95% CI: -2.9 - -1.2; p < 0.001). Sex, age group, study site, specimen quality and referral type were found to be significantly associated with positive TB case detection (p < 0.01). A Control site “Kaneshie polyclinic” with no GeneXpert MTB/RIF assay test, continued to have a decline in positive TB case detection. Also 71/1243 (5.7%) of all positive TB cases detected by GeneXpert MTB/RIF were diagnosed as being Rifampicin resistance. Conclusion: Positive TB case detection using GeneXpert MTB/RIF was higher compared with case detection using Smear Microscopy. Sex, age group, study site, specimen quality and referral type were found to be significantly associated with positive TB case detection.