The technical machinery behind the analysis was rigorous. The researchers followed the PRISMA 2020 reporting guidelines and searched six major databases, including PubMed, Scopus, Embase, Web of Science, the Cochrane Library, and African Journals Online, for studies reporting World Health Organization-defined treatment outcomes among patients with drug-resistant tuberculosis in Cameroon. Rather than relying on simple pooled proportions, the team employed random-effects meta-analyses using generalized linear mixed models with logit transformation, a statistically robust approach that better accommodates the variation inherent in observational studies. Heterogeneity across studies was quantified using the I-squared statistic, and the authors conducted both publication bias assessments and sensitivity analyses to test the stability of their findings. The review was prospectively registered under number CRD420261404490.

The headline numbers tell a nuanced story. Across fourteen reports encompassing 2,351 participants, the pooled mortality rate was 6.8 percent, with a 95 percent confidence interval of 4.7 to 9.7 percent and moderate heterogeneity of 58.1 percent. Loss to follow-up, a persistent scourge of long tuberculosis treatment courses, stood at 4.1 percent across twelve reports covering 2,244 participants. Treatment failure, the outcome that most directly signals regimens not working, was estimated at 4.2 percent, though the striking heterogeneity of 93.3 percent across thirteen reports and 2,050 participants suggests this figure should be interpreted with considerable caution. The pooled treatment success rate, drawing on thirteen reports and 2,146 participants, was 74.2 percent, with a wide confidence interval of 60.4 to 84.4 percent and high heterogeneity of 88.1 percent.

That heterogeneity is not a mere statistical footnote. It reflects the reality that the included studies, most of which were observational cohorts, spanned nearly a quarter of a century of evolving treatment paradigms, from the era of injectable agent-based regimens to the early adoption of shorter and all-oral protocols. Patients treated in 1998 faced radically different drug combinations, diagnostic capacity, and HIV care landscapes than those treated in 2022. The very high I-squared values for treatment failure and treatment success mean the true underlying rates likely vary substantially across settings, patient populations, and time periods within Cameroon, and the pooled estimates should be read as a national synthesis rather than a single universal figure.

Perhaps the most clinically striking findings concern adverse drug events. Among patients with multidrug-resistant tuberculosis, the pooled prevalence of adverse drug events was a remarkable 70.8 percent, based on three studies with 251 participants, though the confidence interval of 40.2 to 89.7 percent is wide. Ototoxicity, damage to the inner ear that can cause permanent hearing loss and balance problems, was the most common event at 41.9 percent, followed closely by gastrointestinal disorders at 40.9 percent. These figures underscore the brutal toll that second-line tuberculosis therapy has historically exacted on patients. Aminoglycoside injectables, long a backbone of multidrug-resistant tuberculosis treatment, are notorious for cochlear and vestibular toxicity, and the high ototoxicity rate in this review is consistent with global experience with injectable-containing regimens.

The predictors of unfavorable outcomes tell an equally important story. HIV co-infection was significantly associated with unfavorable treatment outcomes, with a pooled odds ratio of 2.76 and a 95 percent confidence interval of 1.95 to 3.93 across six studies. In practical terms, patients living with HIV who contracted drug-resistant tuberculosis had nearly three times the odds of dying, failing treatment, being lost to follow-up, or otherwise not achieving cure compared with HIV-negative patients. This finding carries particular weight in Cameroon, where HIV prevalence remains substantial and tuberculosis is the leading cause of death among people living with HIV. The biological rationale is clear: immunosuppression impairs the body’s ability to contain infection, drug interactions between antiretrovirals and second-line tuberculosis drugs complicate therapy, and overlapping toxicities can force regimen modifications that undermine efficacy.

Male sex emerged as the second significant predictor, with men showing 73 percent higher odds of unfavorable outcomes than women, based on a pooled odds ratio of 1.73 across five studies. This pattern echoes a well-documented global phenomenon in tuberculosis care. Men consistently account for the majority of tuberculosis cases worldwide, are more likely to delay seeking care, face greater barriers to adherence including occupational and mobility constraints, and experience worse retention in care. In the context of a drug-resistant disease requiring eighteen to twenty months of therapy under older regimens, these structural and behavioral disadvantages compound into measurably worse outcomes.

The authors’ conclusions point toward concrete solutions. They argue that strengthening pharmacovigilance, the systematic detection and monitoring of adverse drug events, is essential given that more than two-thirds of multidrug-resistant tuberculosis patients experienced significant drug toxicity. Early detection of hearing loss, for example, allows clinicians to modify regimens before irreversible damage occurs, and active adverse event monitoring improves patient retention. Equally critical, they emphasize, is the integration of tuberculosis and HIV services, ensuring that co-infected patients receive coordinated antiretroviral therapy and tuberculosis treatment rather than fragmented care that increases mortality risk.

The most consequential recommendation, however, concerns the transition to all-oral regimens. The data synthesized in this review largely reflect the era of injectable-containing therapy, with its attendant ototoxicity and injection-site complications. Newer all-oral short-course regimens built around bedaquiline and other modern drugs have demonstrated superior efficacy and dramatically better tolerability in global trials and programmatic rollouts. For Cameroon, implementing these regimens nationwide would address several of the review’s findings simultaneously: reducing the catastrophic adverse event burden, potentially improving treatment success toward the 85 percent national target, and making the long treatment journey more humane for patients.

The study is not without limitations inherent to its design. The reliance on observational cohort studies, the wide confidence intervals around several estimates, and the substantial heterogeneity all counsel careful interpretation, and the authors themselves acknowledge these constraints. Yet the value of this work lies precisely in its synthesis: for the first time, Cameroon has a nationally representative, statistically rigorous estimate of how its drug-resistant tuberculosis program is performing. With mortality near 7 percent, one in twenty patients lost to follow-up, and one in four not achieving cure, the gap between current reality and national ambitions is now quantified. Closing that gap, the review makes clear, will require not just better drugs but better systems: vigilant drug safety monitoring, seamless HIV integration, and the political commitment to bring modern, all-oral therapy to every patient who needs it.

Subject of Research: Treatment outcomes of drug-resistant tuberculosis in Cameroon

Article Title: Treatment outcomes of drug-resistant Mycobacterium tuberculosis disease in Cameroon: a systematic review and meta-analysis

Article References: Cheuyem, F. Z. L., Touko, A. D., Achangwa, C., Tchamani, R., Otsali, R. K. N., Mapouo, C. J. K., & Temgoua, M. N. (2026). Treatment outcomes of drug-resistant Mycobacterium tuberculosis disease in Cameroon: a systematic review and meta-analysis. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14591-x

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14591-x

Keywords: drug-resistant tuberculosis, Mycobacterium tuberculosis, Cameroon, systematic review, meta-analysis, treatment outcomes, HIV co-infection, adverse drug events, ototoxicity, pharmacovigilance, all-oral regimens, treatment success rate