Tuberculosis (TB) is a major public health concern in the developing world. According to the World Health Organization (WHO) report in 2018, TB caused an estimated 1.3 million deaths (range, 1.2–1.4 million) among Human Immunodeficiency Virus (HIV)-negative people and there were an additional 300,000 deaths from TB (range, 266,000–335,000) among HIV-positive people [1]. Globally, the best estimate is that 10.0 million people (range, 9.0–11.1 million) developed TB disease in 2017: 5.8 million men, 3.2 million women and 1.0 million children. WHO’s list of 30 high TB burden countries accounted for 87% of the world’s cases [1].

The annual infection rate in developing countries reached 2% or more; where as in developed countries this figure is 0.5% [2]. In Africa, more than 4 million people suffer from active TB and 650,000 deaths occurring every year [3].

According to Ethiopian national TB guidelines: relapses, failure, return after loss to follow-up and other are the four categories to define previously treated TB patients. ‘Other’ includes chronic re-treatment TB patients, recurrent smear-negative pulmonary tuberculosis (PTB) and extra-pulmonary tuberculosis (EPTB) [4-6].

Previously conducted studies have revealed that retreatment TB cases play major role in the development of drug resistance including Multidrug resistant tuberculosis (MDR-TB) which is considered to be a global threat today [4-7]. The threat effect of TB retreatment at individual, community and country levels both on the economy and mortality of people in Ethiopia is a great problem today [5, 7].

Different studies had identified factors determining the retreatment TB cases such as; socio-demographic factors smear result at enrolment, year of treatment, Anti-TB regimen, patient category and HIV status [8-15]. Therefore, this study is designed to examine both the burden of retreatment TB cases and their treatment outcomes in Nekemte Referral Hospital (NRH) and give an appropriate recommendation based on the findings.

This study aimed to assess the TB retreatment case and their outcomes in NRH. From a total of 219 patients, this study evaluated 199 patients with known treatment outcomes after excluding transferred out patients which are 20 in number and found that only 73.4% of patients had achieved successful treatment outcome. According to WHO target, treatment success rate for high burden TB countries like Ethiopia should be 90% and above. Therefore, this study indicates poor results compared to WHO target [1].

HIV status of the patients was also assessed with 32.9% positive status which is the same with the study done in AHMC [15] which are relatively same with the prevalence of HIV in the community and higher than the study done in Ethiopian Somali region [14]. The might be due to pastoral life style of the patients in these study areas. Studies were done in Uganda [16] and Benin [17] revealed that unknown HIV status was significantly associated with poor treatment success compared to known HIV status, however, in both studies, no statistical difference was seen between HIV- positive and HIV- negative patients on treatment outcome. In the present study, no patients with known treatment outcome were registered as unknown HIV status, but similar to the above studies there was no significant difference in treatment and success was found between HIV-positive and HIV-negative patients.

In this study, sex has not shown a statistical difference in treatment outcome. However, studies from Bangalore city of India [18] and Italy [19] had reported that male patients were more likely to have poor treatment outcomes than female patients. Similar to the present study no significant associations were observed between unsuccessful outcome and gender in other studies from the Ethiopian Somali region [14], AHMC [15] and India [20]. This might be due to epidemiological factors and integrated research is required to outline the relative roles played by epidemiology in this area.

Patients who had positive AFB result in 5^th month were 4.3 times more likely to have poor treatment outcomes when compared with patients who had negative AFB results at 5^th months (AOR =4.3, 95%, (1.8-10.0) p=0.001). This is due to the fact that if the patient is found smear positive at the end of the 5^th month of treatment, in two different specimens, the patient is declared as treatment failure.

Based on drug regimens, patients who are on category 1(2ERHZ/4RH) are more likely to have poor treatment outcomes when compared with patients on category 2(2SERHZ/1ERHZ/5ERH). This is the same with the study done in Ethiopian Somali and AMHC [14, 15]. According to Ethiopian national TB guidelines, a retreatment regimen (2SRHZE/1RHZE/5RHE) should have been used for all retreatment cases. But more than half of patients were inappropriately treated with category I regimen (2RHZE/4RH), similarly, the study was done in Uganda [21] and Malawi [22] reported that only 32% and 38% of the patients were on category II regimen respectively. The overall treatment success rate was low among retreatment TB patients receiving category I regimen suggesting that; there was a practice of inappropriate use of regimen. The reason for the inappropriateness might be due to the lack of knowledge of the health care professionals about the recommendations of the guideline and lack of adherence to the guideline.

This study showed that TB retreatment case outcomes were below standard set by the World Health Organization (WHO). The main finding of the study is that half of the patients were given the wrong treatment (Category 1 - standard short course therapy) when all should have had Category 2 treatment (basically the awful WHO Category 2 regimen which involves breaking the cardinal rule of TB management which is never to add a single drug to a failing regimen - apparently this is still standard practice in Ethiopia though it has undoubtedly contributed to the development of drug resistance worldwide. Factors that were significantly associated with poor treatment outcome of retreatment patients were positive smear result of AFB result at 5^th month and drug regimen of category 1(2ERHZ/4RH). We recommend implementation of DOTS plus strategy both at initiation and continuation phases of treatment. To evaluate response of TB retreatment cases monitoring should be done more frequently than the recommended interval to take early action.

Limitation of this study was that the study design we used was a retrospective study which may be subjected to biases. Variables like educational level, adherence, patient-health worker communication and provider and health system related factors because of the retrospective nature of our study were not addressed. Another limitation was that the sample size we used was small.