A Comparative Analysis of Suggestive Radiology versus Sputum Test in the Diagnosis of Tuberculosis at the Defence Forces Memorial Hospital, Kenya

Abstract

Background: Worldwide, there is an increase the number of TB cases in the developing world where the HIV/AIDS scourge has seen resurgence in the numbers of TB cases. The tendency to use a combination of radiological investigations along with sputum studies for TB in Kenya without due regard to the radiation exposure and additional cost warrants a comparative evaluation of the efficacy of the diagnostic tests with a view of avoiding unnecessary tests.

Goal of the Study: The purpose of the study was to determine the effectiveness of radiology imaging versus sputum test in the diagnosis of tuberculosis at DFMH.

Methods: A retrospective comparative analysis of hospital records for TB patients with a view of determining the relationship between suggestive radiology findings for TB versus results of sputum bacteriological studies in the diagnosis of TB at the Defence Forces Memorial Hospital (DFMH) between January and July 2014. The researchers extracted the sputum results, clinical diagnosis, suggestive radiology findings for Tuberculosis, and patient's demographic variables from the hospital data treatments records using a checklist at the Comprehensive Care Clinic (CCC). Data was then summarized and presented in form of tables, bar graphs and pie charts.

Results: Data from the 50 study subjects' records revealed that the majority were of male gender at 72%, while the rest was the female gender at 28%. The mean age of the patients was 34.16 years with a range of between 17-48 years. The majority (58.0%) of the patients' diagnosis indicated suggestive for TB by use of X-ray whereas 14.0% of the patients had normal findings. TB diagnosis made by CT scan was 24% of the patients. Approximately 56.0% of the patients showed negative sputum results while 44.0% results showed the test was positive (p-value of 0.045). Out of the 29 suggestive cases by X-ray, 42.1% had a negative lab test while 57.8% had a positive sputum lab test. Whereas chest x-ray showed that some patients' exams were normal, majority (85.7%) of those cases were reported as positive for TB by lab test and only 14.3% were reported as negative for TB by lab test.

 Conclusions and Recommendations

The use of sputum tests for detection of pulmonary TB is much more sensitive than suggestive radiological findings as previously expressed by other scholars. The role of radiology could be limited to the extra-pulmonary TB diagnosis or situations in which patients lack sputum.

Recommendation

A review of the TB management protocols with a view of limiting concurrent use of radiological and a laboratory investigation for pulmonary TB could scale down the cost of TB investigations.