INTRODUCTION
In line with the end tuberculosis (TB) strategy, through which the World Health Organization (WHO) aims at ending the TB pandemic by 2035,[1] Zambia’s TB case notifications have been steadily increasing over the years. For instance, in 2018, there were 35,922 notifications, which rose to 40,726 in 2020 and 54,848 in 2022, a 52% increase over 5 years.[2] The sustained increases in TB detection and treatment success rate of over 90% have resulted in a rapid decrease in the TB incidence rate estimated by the WHO, which fell to 295 per 100,000 population in 2022 from 391 in 2015.[3] Monitoring and evaluation of treatment outcomes has been given priority in the End TB Strategy as an integral part of the treatment and prevention of TB.[3] Treatment outcomes, as measured by a standardized method, are key indicators of national TB program effectiveness.[4-6]
Several studies have been conducted on factors associated with favorable or unfavorable treatment outcomes.[7-18] Some found that increasing age was associated with poor treatment outcomes.[7-11] Another study found those with unknown HIV status were almost eight times more likely to have unfavorable treatment outcomes.[12] However, to the best of our knowledge, there has never been a study conducted in Zambia identifying factors related to favorable treatment outcomes. This study aimed at assessing TB treatment outcomes and identifying the factors associated with favorable ones at selected health facilities in Lusaka, Zambia.
METHODS
Tuberculosis diagnosis
Presumptive TB patients are identified by health workers and community health volunteers called “treatment supporters” within health facilities and in the community through screening. TB specimens such as sputum, urine, stool, and others are taken to the laboratory for examination. In Zambia, the Ministry of Health recommends the use of molecular methods such as Xpert mycobacterium TB (MTB)/resistance to rifampicin (RIF) for TB diagnosis while microscopy is used for monitoring patients who are on treatment.[13] For some patients, diagnosis is made clinically.
Commencement of tuberculosis treatment and monitoring of patients
Once laboratory results are ready, they are provided to chest clinics. For persons found to have TB, including those who are diagnosed clinically, anti-TB treatment is commenced. Patients come on their own following appointments or are contacted through mobile phones or followed up by treatment supporters to start treatment. Monitoring is done at facilities mainly by TB nurses and in the community by assigned treatment supporters and/or patients’ relatives. For bacteriologically confirmed TB patients, laboratory monitoring is done at 2, 5, and 6 months of treatment by re-examining the specimens.[19]
Patient evaluation
Patients with drug-susceptible disease are normally treated for 6 months, whereas those with severe TB continue treatment for up to 12 months.[19] Therefore, patient evaluation is conducted after 12 months. At the end of treatment, the WHO recommends that each patient be assigned a treatment outcome.[5,19] These outcomes are reported on a monthly basis to the National TB and Leprosy Programme through District Health Offices.
Study sites
The study was conducted in Lusaka, Zambia, at four health facilities: Facility A, a 1st level hospital in an area with a population of 248,279, located in a low-population-density area 9 km from the city center; Facility B, an urban health center in an area with a population of 81,408 located in a very high-population-density area 12 km from the city center; Facility C, a 1st level hospital in an area with a population of 333,530, located in a high-population-density area 10 km from the city center; Facility D, an urban health center in an area with a population of 41,462, located in a low-population-density area 12 km from the city center. These areas were selected as the authors are organizing a project for assisting the National TB Programme of Zambia with regard to improving case finding and holding of patients with TB, utilizing the authors’ past experiences in Zambia and elsewhere.[20-31]
Definitions, study population, and study period
According to the WHO,[5] definitions of TB treatment outcomes are as follows
Cured
A pulmonary TB 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.
Treatment failed
A TB patient whose sputum smear or culture is positive at month 5 or later during treatment.
Died
A TB patient who died for any reason before starting or during the course of treatment.
Lost to follow-up
For a 6-month regimen, a patient diagnosed with TB who did not start treatment or whose treatment was interrupted for 2 consecutive months or more. For a 4-month regimen, a patient diagnosed with TB who did not start treatment or whose treatment was interrupted for more than a week.[6]
Not evaluated
A TB patient for whom no treatment outcome is assigned. This includes cases “transferred out” to another treatment unit as well as cases for whom the treatment outcome is unknown to the reporting unit.
Treatment success
The sum of cured and treatment completed.
The study population consisted of all patients with TB who were registered at the four health facilities for the period January 2022–December 2022. The study was conducted from October 2023 to June 2024.
Type of sampling and reasons for selection
This was a retrospective cohort study involving the review of TB treatment registers without direct interaction with TB patients. The investigators extracted data from treatment registers at the four health facilities on age, sex, address, contact details, type of patient, type of TB, treatment start date, HIV status, and treatment outcomes after verification. Data were recorded on data collection sheets and later transferred and stored in an MS Excel file (Microsoft, Redmond, WA, USA) as a line list.
Inclusion criteria
All patients with drug-susceptible TB who were registered at the four facilities (Facility A through D) from January 2022 to December 2022 and for whom their treatment outcomes could be assessed were included in the study regardless of the age and the type of TB.
Exclusion criteria
Patients who were registered at other health facilities and were transferred in to continue treatment at the study sites were excluded from the study. Patients with drug-resistant TB were excluded from the study because they have a different treatment duration. Patients whose details were incomplete due to incomplete registers were also excluded.
Statistical analysis
Statistical analysis for this study was conducted using R software version x64 4.0.2 (The R Project for Statistical Computing, Vienna, Austria). The primary goal of the analysis was to identify factors associated with favorable treatment outcomes among TB patients. The initial analysis involved calculating descriptive statistics to summarize the demographic and clinical characteristics of the study population. This included frequencies and percentages for categorical variables (e.g., sex and HIV status) and measures of central tendency (mean and median) for continuous variables (e.g., age). Treatment outcomes were classified as favorable (cured or treatment completed) or unfavorable (death, treatment failure, lost to follow-up [LTFU], or not evaluated). This classification allowed for a clear distinction in the analysis. To assess the relationship between various independent variables and treatment outcomes, multiple regression analysis was employed. The dependent variable was defined as a binary outcome (favorable vs. unfavorable). Independent variables included age, sex, HIV status, availability of contact details, and the specific health facility where treatment was received. A logistic regression model was fitted to the data to estimate the odds ratios (ORs) for each independent variable. The model’s goodness-of-fit was assessed using Akaike’s information criterion, and the significance of individual predictors was evaluated using P values, with a significance level set at P < 0.05. For each OR, 95% confidence intervals (CIs) were calculated to provide a measure of the precision of the estimates. These intervals help assess the reliability of the identified associations. Patients with any missing data were excluded from the data. This approach aimed to minimize bias in the analysis. All statistical analyses were performed using R, ensuring rigorous examination and interpretation of the data.
Ethical considerations
This study was conducted as part of the review and monitoring activities of routine TB case management in relation to TB control, and thus informed consent was not necessary to be provided by the individual patients. The study was conducted in accordance with the Declaration of Helsinki. The investigators sought research permission from the Zambia National Health Research Authority, Lusaka, Zambia (Ref. No: NHRA 00005/07/11/2023 dated October 25, 2023) and ethical clearance from the Institutional Review Board of Research Ethics and Science Converge, Lusaka, Zambia (Reference No. 2023-Sep-017 dated October 16, 2023). Confidentiality was observed and maintained at all stages of the study, and only investigators had access to the collected data.
RESULTS
A total of 2945 TB patients were registered at the four health facilities from January 2022 to December 2022 [Table 1]. Of these, 2071 (70.3%) were males and their age ranged from 3 months to 95 years. There were 1346 (45.7%) bacteriologically confirmed patients with TB, whereas 1380 (80.8%) were new patients. The four facilities recorded a treatment success rate of 88.2% and unfavorable treatment outcomes of 11.8% (LTFU: 5.6%; died: 4.8%; not evaluated: 1.5%). There was no patient with treatment failure during the period.
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Table 1: The main characteristics of the patients with tuberculosis in four health facilities, Lusaka, Zambia, 2022
Table 2 demonstrates the results of univariable and multivariable analysis on treatment outcomes of patients with TB in four health facilities in Lusaka, Zambia during 2022. In the multivariable analysis, only four variables remained: age, the availability of contacts of the patients with TB, HIV status, and the facility. Patients were 0.990 (95% CI: 0.981–0.998) times more likely to have a favorable outcome as age advanced year by year (the older, the worse). Patients with contact details recorded in the registers were 2.17 (95% CI: 1.3–3.6) times more likely to have favorable treatment outcomes than those without them. Patients with unknown HIV status were 0.0079 (95% CI: 0.0024–0.0259) times more likely to have favorable outcomes (126.58 times less likely to have favorable outcomes) than those who were HIV negative. Patients at facilities A and B were 4.8 (95% CI: 2.7–8.4) and 1.8 (95% CI: 1.1–3.0) times, respectively, more likely to have favorable outcomes than those at facility D. Facility C did not have significantly different outcomes compared with facility D.
Table 2: The results of univariable and multivariable analysis on treatment outcomes of patients with tuberculosis in four health facilities, Lusaka, Zambia, 2022
DISCUSSION
We conducted a study to determine factors associated with favorable treatment outcomes for TB patients who were registered at four health facilities in Lusaka, Zambia from January 2022 to December 2022. In this study, increasing age and having unknown HIV status were found to be associated with unfavorable treatment outcomes. Patients without contact details (phone numbers, etc.) had about half the favorable outcomes of those for whom these details were available, whereas the type of facilities patients were affiliated with played a role in determining the treatment outcomes. Patients at facilities A and B had better outcomes than those at facility D.
Increasing age was found to be associated with unfavorable treatment outcomes because it is attributed to age-related comorbidities resulting in poor treatment outcomes.[32,33] There is a need for older people to be given proper medical attention as they seek TB treatment. Health care should go beyond TB disease, and they should be assessed for the presence of comorbidities, treated, and monitored throughout the TB treatment period.
With regard to contact details, the importance of communication between health workers and patients cannot be overemphasized. This study was conducted in an urban setting where the majority of patients had access to phones and a good mobile phone network. However, a few patients may not have had phones, or they may have had them but gave incorrect phone numbers either consciously or unconsciously. Similarly, because of a lack of understanding about the importance of communication, some health workers may also have decided not to collect phone numbers from patients. Thus, it was easier to lose contact with such patients. Health workers should be encouraged to document all necessary patient details, including addresses and sketch maps with landmarks as well as phone numbers.
The study also established that patients with unknown HIV status were more prone to poor treatment outcomes than those with known HIV status. Patients with unknown HIV status may have been tested but not properly documented or not tested at all. During the year under review (2022), for example, 5% of TB patients in Zambia had unknown HIV status.[2] HIV-positive patients with TB who are not undergoing antiretroviral therapy (ART) suffer from high mortality.[34] On the other hand, most HIV-positive TB patients receive ART, and this contributes to favorable TB treatment outcomes. For instance, 98% of HIV-positive TB patients in Zambia received ART in 2022,[2] and the treatment success rate was 90% in this category.[3] Health facilities should strive to test all TB patients for HIV and those found to have it must commence ART.
In this study, receiving care and treatment from facilities A and B were associated with more favorable treatment outcomes than in facility D. Of note is that these four facilities have similar urban settings and numbers of trained human resources in chest clinics. However, they vary in terms of catchment populations, number of patients, and distances patients cover to reach them among others. Facility C, for instance, has the highest catchment area and TB patient population, but approximately one-third of the TB patients came from outside this catchment area, making it difficult for the staff members to monitor the patients. In addition, the two available nurses in the department may find it difficult to handle a high number of patients with TB. We as a project have trained the clinicians and nurses in TB management and monitoring, the laboratory staff in Xpert MTB/RIF and microscopy and provided quarterly technical assistance with the hope of improving performance.
Facility D, though it had the smallest number of TB patients, had the highest proportion (15.6%) of the LTFU patients with TB. This could be attributed to the long distances some patients covered to reach the facility and the fact that some of the lost patients had no fixed abode (street people) among other reasons. With the opening of a smaller health facility within the catchment area, patients from distant places have started getting TB services from within their localities. This will help ease the problem. Mapping for street TB patients can also be done to determine their exact locations and link them to treatment supporters and community-based organizations.
Several studies have been conducted on factors associated with unfavorable treatment outcomes. Our study is consistent with many other studies which have found that increasing age is associated with poor treatment outcomes.[7-10] One study in India reported that older TB patients had a 38% higher risk of poor outcomes than other TB patients.[11] With regard to HIV, a study conducted at Jimma University Medical Center in Ethiopia found that patients with unknown HIV status were almost eight times more likely to have unfavorable treatment outcomes.[12] As for contact details, our findings that the patients with contact details available had twice the favorable treatment outcomes of those without them were similar to those of a study conducted in Puducherry, India, where the use of mobile phones to contact patients for TB treatment initiation reduced the pretreatment LTFU by 9%.[35]
This study has both strengths and limitations. It isolated specific factors that affect the TB treatment outcomes at the four study sites. Health facilities will propose solutions based on these findings with the aim of improving performance. While some studies have been done on this topic, consideration was not given to the significance of collecting patients’ phone numbers, the importance of which in improving TB treatment outcomes this study has highlighted. However, we only considered TB treatment register-based variables, which are quite limited. The study did not include other socioeconomic variables that may also play a role in determining treatment outcomes. Furthermore, some patients were excluded from the study because of the unavailability of data as a result of damaged registers, and this may have affected the study outcomes. In addition, our findings for the four health facilities do not represent the entire Lusaka district.
CONCLUSION
This study identified several key factors associated with favorable treatment outcomes for TB patients in Lusaka, Zambia. Notably, younger age, known HIV status, the availability of contact details, and treatment at specific health facilities were positively associated with successful outcomes. Older patients, in particular, require additional care that extends beyond TB management, emphasizing the need for comprehensive health assessments to address potential comorbidities. The findings highlight the critical importance of collecting accurate patient contact information to facilitate ongoing communication and support throughout the treatment process. Moreover, the study underscores the necessity of routine HIV testing for TB patients, as those with unknown HIV status face significantly poorer treatment outcomes. Healthcare facilities should implement strategies to ensure that all TB patients are tested for HIV and, if positive, receive timely ART. In conclusion, targeted interventions based on these identified factors can enhance TB treatment success rates, ultimately contributing to improved public health outcomes in Zambia. Efforts must focus on addressing the identified barriers to treatment success to meet national and global TB elimination goals effectively.
Outcome of the study
The study on factors associated with favorable TB treatment outcomes in Lusaka, Zambia, yielded the following key findings:
Overall treatment success rate: Among the 2945 registered patients, the treatment success rate was 88.2%, indicating a significant proportion of patients achieved favorable outcomes.
Demographics
The majority of patients (70.3%) were male, and 45.7% had bacteriologically confirmed TB. A large segment (80.8%) were new patients.
Impact of age
The analysis revealed that for each additional year of age, the likelihood of achieving favorable treatment outcomes decreased by 0.99 times, highlighting the challenges faced by older patients.
HIV status
Patients with unknown HIV status were found to be 0.0079 times more likely to have favorable outcomes compared to those who were HIV-negative, underscoring the critical role of known HIV status in treatment outcomes.
Contact information
Patients whose contact details were recorded had 2.17 times higher odds of favorable outcomes than those without contact information, emphasizing the importance of maintaining communication throughout treatment.
Facility differences
Patients treated at Facility A and B had significantly higher odds of favorable outcomes compared to those at Facility D, with ORs of 4.8 and 1.8, respectively. This suggests variability in treatment efficacy based on healthcare facilities.
Recommendations for improvement
The findings indicate a need for healthcare providers to prioritize collecting patient contact information, conducting routine HIV testing, and enhancing support for older patients to improve overall treatment outcomes. In summary, the study underscores the importance of targeted interventions and comprehensive patient management strategies to enhance TB treatment success and address the specific needs of the vulnerable population.
Rationale for the study
The rationale for this study stems from the urgent need to understand and improve TB treatment outcomes in Lusaka, Zambia, amid rising TB notification rates. Despite global efforts to combat TB, challenges remain, particularly in resource-limited settings where healthcare access and treatment adherence can significantly impact patient outcomes.
Increasing tuberculosis burden
Zambia has witnessed a steady increase in TB case notifications, with a reported rise from 35,922 in 2018 to 54,848 in 2022. This escalating trend necessitates a deeper investigation into the factors that influence treatment success.
Lack of local research
While numerous studies globally have explored factors associated with TB treatment outcomes, there is a notable gap in research focused specifically on Zambia. This study aims to fill that gap by providing localized data that can inform national health policies and interventions.
Importance of treatment outcomes
Treatment outcomes are critical indicators of the effectiveness of TB control programs. Understanding which factors contribute to favorable outcomes can help healthcare providers tailor interventions to improve patient management and adherence.
Targeting vulnerable populations
Older patients and those with unknown HIV status are particularly at risk for unfavorable treatment outcomes. By identifying specific barriers faced by these groups, the study seeks to enhance support mechanisms and improve overall care.
Data-driven interventions
The study employs robust statistical methods, such as multiple regression analysis, to provide evidence-based insights. These findings can guide healthcare providers in implementing targeted strategies, such as improving communication through contact details collection and ensuring timely HIV testing.
Alignment with global health goals
The study aligns with WHO’s End TB Strategy, which aims to eliminate TB as a public health threat by 2035. By addressing local factors influencing treatment outcomes, the research contributes to the broader goals of reducing TB incidence and mortality.
In conclusion, this study is essential for advancing our understanding of TB treatment outcomes in Zambia, enabling healthcare providers to develop effective, culturally relevant interventions that can lead to improved patient care and public health outcomes.
Limitations of the study
Retrospective design
The study’s retrospective cohort design relies on existing treatment records, which may be incomplete or inaccurately documented. This could affect the reliability of the data and the outcomes derived from it.
Time frame limitations
The study focuses on TB patients registered in 2022, which may not fully capture trends of changes in treatment outcomes over time, especially in a dynamic public health landscape.
Financial support and sponsorship
Ministry of Foreign Affairs of Japan under the Grant for Nongovernmental Organizations (A Project for Tuberculosis Control in Lusaka district through Improving Diagnosis).
Conflicts of interest
There are no conflicts of interest.
Acknowledgment
The authors would like to thank all the staff members and the community volunteers at the study sites, the Lusaka District Health Office, the Lusaka Provincial Health Office, the Ministry of Health of the Republic of Zambia, and the JATA Zambia and JATA HQ. The study was partially supported by the Ministry of Foreign Affairs of Japan and the Japan Anti-Tuberculosis Association.
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