Discrepancies in neglected tropical diseases burden estimates in China: comparative study of real-world data and Global Burden of Disease 2021 data (2004-2020)
BMJ 2025; 388 doi: https://doi.org/10.1136/bmj-2024-080969 (Published 18 February 2025) Cite this as: BMJ 2025;388:e080969Linked Editorial
Neglected tropical diseases in China
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Dear Editor,
Guo-Jing Y and colleagues (doi:10.1136/bmj-2024-080969) compared the disability-adjusted life years (DALYs) estimated from the database of Chinese Center for Disease Control and Prevention and the DALYs estimated from the database of the GBD 2021 for six neglected tropical diseases (dengue, echinococcosis, leishmaniasis, leprosy, rabies, and schistosomiasis).
Guo-Jing and colleagues call their DALYs “real-world DALYs”. However, no such thing as a real-world DALY exists, simply because DALYs are the product of estimated measures, approximations and arbitrarity.
What is unclear to the reader is why Guo-Jing and colleagues did not start by comparing incidence, prevalence and mortality due to these neglected tropical diseases. From there, it would have been useful to understand the differences – and the reasons for such differences – in the other elements required to calculate years lived with disability (YLDs) and years of life lost (YLLs). Instead, the authors in the article skip to presenting the DALYs and leave the readers with uncertainty about the real causes that make “real-world DALYs” so different from GBD DALYs.
Thus, the questions the authors should be able to answer are the following:
1. How different are the real-world incidence, prevalence and mortality of the neglected tropical diseases considered, if compared to those estimated by the GBD?
2. What is the difference in the real-world average duration of each disease calculated by the authors, if compared to the durations considered in the GBD?
3. How different is the life expectancy considered by the authors, if compared to the global one used in the GBD? Consider that the GBD adopts a global ideal life expectancy because the principle is that everyone on earth deserves the highest possible one.
4. What about Disability Weights? In my understanding, the authors took the ones also adopted by the GBD Project. Why? Why not, instead, use locally adapted DW, which would account for better culturally tuned perceptions?
Competing interests: No competing interests
Re: "Questioning Global Health Metrics: Are GBD Estimates Misrepresenting China's NTD Burden?"
Dear Editor
Guo-Jing et al. 2025 [doi: https://doi.org/10.1136/bmj-2024-080969] explore the disparities between China’s real-world disability-adjusted life years (DALYs) for NTDs and estimates provided by GBD 2021 [1]. This study uncovered the applicability of the GBD model and the effectiveness of China’s disease control policies. Nevertheless, a few critical aspects warrant scrutiny.
Firstly, the study advocates for the superiority of China’s real-world data over GBD estimates but does not assess the inherent biases of national data collection critically. Despite having reliable surveillance systems, limitations such as misclassification, underreporting, and inconsistencies are not accounted for [2]. Additionally, relying on China’s official report remains a recipe for confirmation bias.
Secondly, the study acknowledges that underreporting is a serious concern but does not elucidate its implications for the validity of China’s real-world DALYs. Certain NTDs, such as dengue, may be underreported due to unrecorded asymptomatic cases and limited healthcare access in rural areas [3].
Also, the authors do not determine whether GBD’s methodology might be more feasible in compensating for such underreporting. Additionally, the study focuses only on 6 TNDs at the expense of the other 15 and fails to offer justification for choosing only those. NTDs such as trachoma are still prevalent in China. This disposition raises concerns about how the discrepancies in the study compare with other NTDs not included in the analysis. Methinks a broader comparison would map the differences.
Lastly, the study compares real-world DALYs and GBD estimates but does not employ a formal statistical test to evaluate the significance of the highlighted differences. Without statistical validation, the outcomes depend significantly on absolute comparison that may not reflect inherent variations in disease burden [4].
References
[1] Yang GJ, Ouyang HQ, Zhao ZY, Li WH, Fall IS, Djirmay AG, et al. Discrepancies in neglected tropical diseases burden estimates in China: comparative study of real-world data and Global Burden of Disease 2021 data (2004-2020). BMJ. 2025 Feb 18;e080969.
[2] Gibbons CL, Mangen MJJ, Plass D, Havelaar AH, Brooke RJ, Kramarz P, et al. Measuring underreporting and under-ascertainment in infectious disease datasets: a comparison of methods. BMC Public Health [Internet]. 2014 Feb 11;14(1). Available from: https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-14-147
[3] Herricks JR, Hotez PJ, Wanga V, Coffeng LE, Haagsma JA, Basáñez MG, et al. The global burden of disease study 2013: What does it mean for the NTDs? Zhou XN, editor. PLOS Neglected Tropical Diseases. 2017 Aug 3;11(8):e0005424.
[4] McClimans L. Interpretability, validity, and the minimum important difference. Theoretical Medicine and Bioethics. 2011 Jul 27;32(6):389–401.
Competing interests: No competing interests