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| ORIGINAL ARTICLE |
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| Year : 2021 | Volume
: 19
| Issue : 4 | Page : 248-252 |
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Tuberculosis treatment outcomes and its associated factors in a tertiary health center in Southwestern Nigeria: A 5-year retrospective review
Abiona Oluwadamilola Odeyemi1, Abiodun R Ojewuyi2, Abimbola Ololade Odeyemi3, Amadin A Olotu3
1 Department of Medicine, College of Health Sciences, Bowen University, Ogbomoso, Oyo State, Nigeria
2 Department of Medical Microbiology and Parasitology, College of Health Sciences, Bowen University, Ogbomoso, Oyo State, Nigeria
3 Department of Paediatrics, College of Health Sciences, Bowen University, Ogbomoso, Oyo State, Nigeria
| Date of Submission | 03-May-2021 |
| Date of Decision | 05-Jun-2021 |
| Date of Acceptance | 27-Jun-2021 |
| Date of Web Publication | 07-Dec-2021 |
Correspondence Address:
Dr. Abiona Oluwadamilola Odeyemi
Department of Pediatrics, College of Health Sciences, Bowen University, Ogbomoso, Oyo State
Nigeria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/cmi.cmi_51_21
Background: Monitoring and evaluation of tuberculosis (TB) treatment outcome is an essential component of the evaluation of a country's TB control program. Nigeria's current TB treatment success rate of 86% is below the World Health Organization target of 90% by 2025. This study aims to evaluate TB treatment outcomes in a tertiary health center in southwestern Nigeria over a 5-year period and to document the factors associated with poor TB treatment outcomes. Materials and Methods: This was a retrospective study of all TB patients seen at the TB clinic of the hospital from January 1, 2015, to December 31, 2019. Data were extracted from the TB clinic register. Data extracted included sociodemographic factors, HIV status, treatment category, rifampicin resistance, extrapulmonary TB, and treatment outcome. Treatment outcome was categorized as successfully treated or poor treatment outcome (death, treatment failure, and lost to follow-up). Results: Five hundred and nine TB cases were analyzed with a mean (standard deviation) age of 40.2 (17.7) years. Treatment outcome was as follows: successfully treated – 426 (83.7%), died – 62 (12.2%), treatment failure – 14 (2.8%), and lost to follow-up – 7 (1.4%). Poor treatment outcome was associated with older age (P = 0.003), HIV-positive status (P = 0.044), and smear-negative TB (P = 0.047). Conclusion: The treatment success rate in our center is high but can be improved. More efforts should be put in place to ensure improved outcomes, particularly among the elderly and HIV-positive patients.
Keywords: Treatment outcome, success rate, tuberculosis, TB
How to cite this article:
Odeyemi AO, Ojewuyi AR, Odeyemi AO, Olotu AA. Tuberculosis treatment outcomes and its associated factors in a tertiary health center in Southwestern Nigeria: A 5-year retrospective review. Curr Med Issues 2021;19:248-52 |
How to cite this URL:
Odeyemi AO, Ojewuyi AR, Odeyemi AO, Olotu AA. Tuberculosis treatment outcomes and its associated factors in a tertiary health center in Southwestern Nigeria: A 5-year retrospective review. Curr Med Issues [serial online] 2021 [cited 2023 Jun 6];19:248-52. Available from: https://www.cmijournal.org/text.asp?2021/19/4/248/331830 |
| Introduction | |  |
Tuberculosis (TB) is a chronic infectious disease caused by bacteria of the Mycobacterium tuberculosis. It is one of the oldest diseases of humans, and despite the successes achieved so far in the control, it continues to be of major public health concern. TB is one of the top ten causes of death and the leading cause from a single infectious agent (above HIV/AIDS) all over the world.[1] It is estimated that about 10 million people developed TB disease all over the world in the year 2018, out of which 429,000 were in Nigeria, representing 4% of the global total.[1] About 1.451 million people were said to have died of TB in the year 2018 with about 157,000 of these deaths occurring in Nigeria.[1]
In order to mitigate the scourge of TB, the Nigerian government established the National TB and Leprosy Control Program in 1991 and it subsequently adopted the World Health Organization (WHO)-recommended Directly Observed Treatment Short-Course (DOTS) strategy in 1993. The DOTS strategy, which was set up to eliminate TB, has five components including political commitment, case detection by bacteriology, standardized treatment with supervision, effective drug supply, and treatment monitoring.[2]
Monitoring and evaluation of treatment outcomes in patients with TB is an essential component of the treatment and prevention of TB. In addition, evaluating TB treatment outcomes and their associated factors is an important indicator of the effectiveness of a country's TB control program.[1] Among other reasons, treatment outcomes are monitored to improve treatment success rates. According to the latest available data, the global TB treatment success rate was put at 85% in the year 2017 while it was 86% in Nigeria in the same year.[1] These figures are both lower than the 90% target by the year 2025 which was set by the WHO through its “;End TB” Strategy.[1]
Improvement in success rates can only be achieved by identifying vulnerable population and the risk factors for poor treatment outcomes. Several factors have been associated with unfavorable treatment outcomes in Africa.[3],[4],[5],[6] In a study done in Nigeria by Ogbudebe et al., it was observed that being male, having pulmonary TB (PTB), being a re-treatment case, having a positive smear at the 2nd month of follow-up, and being smear negative after 2 months of treatment were associated with unfavorable TB treatment outcomes.[4] Another study in Zambia by Nanzaluka et al. found that unfavorable treatment outcomes were associated with being HIV positive, being more than 59 years old, being a relapse case, and receiving care from the urban clinic.[5] In another study in Mozambique, it was observed that having a negative smear result at diagnosis, being male, being a re-treatment case, and being HIV positive were associated with unfavorable treatment outcomes.[6]
Nigeria is one of the eight countries accounting for two-thirds of the global total and one of the WHO's 30 high TB burden countries. Currently, the TB treatment success rate in Nigeria is less than the WHO target of 90% by the year 2025. Nigeria has adopted the WHO “;End TB” Strategy which aims, among other things, to meet this target. To assess the usefulness of this strategy and to achieve this goal, it is important to accurately document and report the treatment outcomes of TB patients and also to identify the factors associated with poor treatment outcomes. This study, therefore, aims to evaluate TB treatment outcomes in a tertiary health center in southwestern Nigeria over a 5-year period spanning 2015–2019 and to document the factors associated with poor TB treatment outcomes with a view to achieving improved treatment outcomes.
| Materials and Methods | | |
This was a retrospective study of all TB patients seen at the DOTS TB clinic of our hospital from January 1, 2015, to December 31, 2019. The clinic is supported by two nongovernmental organizations (the Global Fund and Caritas Nigeria) under the supervision of the Oyo State TB and Leprosy Control Program. On account of its location within the hospital, in addition to serving the people residing within its locality, it also serves people from across the town and neighboring towns. The researchers extracted data from the treatment card and register of all patients seen during the study period. Data extracted included sociodemographic factors, HIV status, treatment category, rifampicin resistance, extrapulmonary TB, and treatment outcome. Ethical approval was obtained from the Research Ethics Committee of Bowen University Teaching Hospital (BUTH) with protocol number BUTH/REC/140.
Definition of terms (according to the World Health Organization)
- Tuberculosis case: Either a bacteriologically confirmed biological specimen positive by either smear microscopy or GeneXpert or clinically diagnosed with TB by a clinician or other medical practitioner who has decided to give the patient a full course of TB treatment.[7]
- Successfully treated (good treatment outcome): A combination of “;cured” and “;treatment completed”
- Cured: A PTB patient with bacteriologically confirmed TB at the beginning of treatment who was smear or culture negative in the last month of treatment and on at least one previous occasion
- Treatment completed: A TB patient who completed treatment without evidence of failure but with no record to show that sputum smear or culture results in the last month of treatment and on at least one previous occasion were negative, either because tests were not done or because results are unavailable
- Poor treatment outcome: This refers to patients who either died or were lost to follow-up or had treatment failure
- Death: A TB patient who died for any reason before starting or during the course of treatment
- Lost to follow-up: A patient who did not start treatment or treatment interrupted for 2 consecutive months or more
- Treatment failure: A patient whose sputum smear or culture is positive at month 5 or later during treatment.
Data management and analysis
The data obtained were analyzed using the Statistical Package for the Social Sciences (SPSS) version 20.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were expressed as means (standard deviation [SD]). Relationship between categorical variables was determined using Pearson Chi-square. P <0.05 was considered statistically significant.
| Results | | |
The clinic had a total of 524 TB cases during the 5-year period. Fifteen of these were excluded from the analysis because they were transferred to other centers to complete their treatment on account of proximity to their places of abode; hence, 509 TB cases were analyzed. One hundred and ninety-three (37.9%) of the patients were female and they had a mean age (SD) of 40.2 (17.7) years. Sixty-nine (13.6%) of them were HIV positive and 54 (10.6%) of them were re-treatment cases [Table 1]. The treatment success rate over the 5-year period was 83.7%. Sixty-two (12.2%) of the patients died and this corresponds to 74.7% of those with poor treatment outcome [Table 2]. Poor treatment outcome was associated with older age, HIV-positive status, and smear-negative TB [Table 3]. The percentage of people with the factors associated with poor treatment outcome was highest in the year 2019 [Table 4]. The annual treatment success rate during the study period ranged from 71.9% to 90.7% [Figure 1]. | Table 3: Relationship between the patients' characteristics and the treatment outcome
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 | Table 4: Five-year tuberculosis treatment success rate and factors associated with poor treatment outcome
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| Discussion | | |
The study has shown that the overall treatment success rate during the 5-year period (2015–2019) was 83.7% and the treatment success rate for each year from 2015 to 2019 was 71.9%, 84.3%, 87.1%, 90.7%, and 83.9%, respectively, with poor treatment outcome being associated with older age (P = 0.003), HIV-positive status (P = 0.044), and smear-negative TB (P = 0.047). Although below the WHO target of 90% by 2025,[1] our finding of 87.1% in the year 2017 is comparable to the latest global and national treatment success rate of 85% and 86%, respectively, which were also recorded in the year 2017.[1] This suboptimal treatment success rate is mainly due to death, which occurred in 74% of those with poor treatment outcome. Our study revealed that poor treatment outcome was associated with older age. This finding is similar to those of earlier studies where it was observed that poor treatment outcome was more likely to occur in people of older age group.[5],[8] This finding may be due to the fact that aging is associated with a decline in immune function,[9] leading to increased susceptibility to infections (including TB) and subsequently death (a major contributor to poor treatment outcome).
Our study also revealed that being HIV positive was associated with poor treatment outcome. This finding is similar to that of Ali et al. who observed that being HIV positive increases the likelihood of a poor treatment outcome among TB patients.[10] Furthermore, earlier studies conducted in South Africa[11] and Finland[12] have shown that HIV/TB coinfection is associated with lower cure rates and higher mortality rates. The poor treatment outcome can be due to the fact that HIV-infected patients tend to have a decline in their CD4 cells as the infection progresses and this is associated with a corresponding decline in immune system, hence making the patient vulnerable to not just TB but also to other opportunistic infections.[13] In addition, malabsorption of drugs in HIV-infected patients, particularly rifampicin and isoniazid,[14] may also be responsible for treatment failure in this category of patients.
In addition, we also observed that poor treatment outcome was associated with having a smear-negative TB. This finding is similar to some earlier studies.[6],[15],[16] For instance, Harries et al. observed that treatment outcome was significantly better in those with smear-positive TB as compared to those with smear-negative TB.[15] Similarly, in a 5-year retrospective study in Ethiopia by Tola et al., it was also observed that the treatment success rate was higher in those with smear-positive TB than those with smear-negative TB.[16] This may be due to the fact that some of these patients may have been wrongly diagnosed with TB with the antituberculous therapy not being helpful, hence leading to lack of access or delayed access to the appropriate treatment for their condition. In addition, higher mortality rates in patients with smear-negative TB may also be due to advanced HIV-related immunosuppression. Patients with advanced HIV-related immunosuppression tend to have smear-negative TB. This can be attributed to the fact that they are unable to mount up an adequate immune response to the causative organism (Mycobacterium tuberculosis), hence they are unable to form cavities and transfer the bacilli into respiratory secretions.
Socioeconomic factors such as level of education, employment status, smoking status, and alcohol consumption may also have an impact on patient treatment outcomes, but we were unable to explore these factors on account of unavailability of the data.
A look at the trend of the success rate over the years reveals that there was a steady rise in the TB treatment success rate up to a peak of 90.7% in the year 2018 and this was followed by a drop to 83.9% in the year 2019 [Figure 1]. While the steady rise may have been due to an improvement in the care of TB patients over the years, the drop in the success rate in the year 2019 may be due to the fact that the percentage of people with the factors associated with poor treatment outcome (older age, HIV-positive status, and smear-negative TB) was greater in that year than in the other years [Table 4].
| Conclusion | | |
The overall treatment success rate for TB in our center over the 5-year period is high but still below the WHO recommended target; hence, there is room for improvement. More efforts should, therefore, be put in place to ensure improved outcomes, particularly among the elderly and HIV-positive patients. Furthermore, efforts should be made to further improve HIV care in Nigeria as this will go a long way in achieving a better treatment outcome in HIV-infected patients including those with HIV/PTB coinfection.
Research quality and ethics statement
The authors of this manuscript declare that this scientific work complies with reporting quality, formatting, and reproducibility guidelines set forth by the EQUATOR Network. The authors also attest that this clinical investigation was approved by the Institutional Review Board/Ethics Committee of BUTH with protocol number BUTH/REC/140. We also certify that we have not plagiarized the contents in this submission and have done a plagiarism check.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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| 14. | Gurumurthy P, Ramachandran G, Hemanth Kumar AK, Rajasekaran S, Padmapriyadarsini C, Swaminathan S, et al. Malabsorption of rifampin and isoniazid in HIV-infected patients with and without tuberculosis. Clin Infect Dis 2004;38:280-3. |
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[Figure 1]
[Table 1], [Table 2], [Table 3], [Table 4]
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