Estimation of disability weight for paragonimiasis: a systematic analysis

Feng et al. Infectious Diseases of Poverty https://doi.org/10.1186/s40249-018-0485-5 (2018) 7:110 SCOPING REVIEW Open Access Estimation of disability weight for paragonimiasis: a systematic analysis Yun Feng1,2,3, Thomas Fürst4,5, Lu Liu1,2,3 and Guo-Jing Yang1,2,3,4,5* Abstract Background: Paragonimiasis, caused by helminths of the genus Paragonimus spp., is a neglected tropical disease. Human suffering from paragonimiasis is often misunderstood and its quantification by the disability weight of the disability-adjusted life years largely varies in different global burden of disease (GBD) estimates. This paper is to systematically review clinical paragonimiasis cases and requantify the disability weight of human paragonimiasis. Methods: A systematic analysis was conducted using articles from the following databases: PubMed, Institute for Scientific Information Web of Science, China National Knowledge Infrastructure, the Chinese scientific journal databases Wanfang Data and CQVIP, Africa Journal Online, and the System for Information on Grey Literature in Europe. Search terms were the combination of “paragonim*” with “clinical” or “infection”. Only articles fulfilling the following conditions were recruited for this study: the occurrence of clinical signs and symptoms of paragonimiasis in human beings were reported; diagnosis was confirmed; no comorbidities were reported; the reviewed clinical cases or epidemiological findings were not already included in any other articles. The information and frequencies of paragonimiasis outcomes from included articles using predefined data fields were extracted two times by two separate individuals. Outcome disability weights were selected mainly from the GBD 2004 and GBD 2013 datasets. Frequencies and disability weights of paragonimiasis outcomes were modelled into a decision tree using the additive approach and multiplicative approach, respectively. Monte Carlo simulations were run 5000 times for an uncertainty analysis. Results: The disability weight estimates of paragonimiasis were simulated with 5302 clinical cases from 80 general articles. The overall disability weight was estimated at 0.1927 (median 0.1956) with a 95% uncertainty interval (UI) of 0.1632–0.2378 using the additive approach, and 0.1791 (median 0.1816) with a 95% UI of 0.1530–0.2182 using the multiplicative approach. The simulated disability weights of Paragonimus westermani cases were higher than that of P. skrjabini cases. Lung outcomes and headache were the top two contributors to disability weight for both species. Conclusions: The use of paragonimiasis disability weight needs to be reconsidered with regard to availability of morbidity data and species variation. Calculating the disease burden of paragonimiasis requires further modification and thus has considerable implications for public health prioritization in research, monitoring, and control. Keywords: Paragonimiasis, Disability weight, Disease burden, Disability-adjusted life years * Correspondence: 1 Jiangsu Institute of Parasitic Diseases, 117 Meiyuan Yangxiang, Wuxi City, Jiangsu Province 214064, People’s Republic of China 2 Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Wuxi, People’s Republic of China Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Feng et al. Infectious Diseases of Poverty (2018) 7:110 Page 2 of 9 Multilingual Abstracts Please see Additional file 1 for translations of the abstract into the five official languages of the United Nations. Background Paragonimiasis is a neglected tropical disease (NTD) [1] caused by helminths of the genus Paragonimus spp., whose eggs hatch in freshwater and yield motile miracidia. The miracidia further develop into motile microcercous cercariae in freshwater snails and later grow into metacercariae in crustaceans like crab or crayfish. Ingestion of contaminated, undercooked freshwater crabs or crayfish leads to paragonimiasis [2]. Paragonimiasis is not usually considered a national or regional public health priority, but due to its wide distribution and severe health consequences in endemic regions, the disease should not be neglected. Paragonimiasis is endemic in parts of Africa, North and South America, and particularly in Southeast and East Asian countries such as China, Japan, and the Philippines [3, 4]. The prevalence of paragonimiasis in northeastern India can reach as high as 51.7% in children aged under 15 years and 18.7% in adults [5]. The disease can also occur in non-endemic areas; for instance, in returning travellers or through infections caused by internationally traded and contaminated raw freshwater crab or crayfish [2, 6]. With the gradually increasing aquaculture production of freshwater crustacea worldwide [7], the endemicity and re-emergence of paragonimiasis deserve more attention [8]. Paragonimiasis causes complex symptoms in multiple organs. Chest symptoms are its most remarkable clinical features, as it is mainly in the lung parenchyma that adult worms exist in pairs encapsulated in fibrous cysts [2, 9]. For some Paragonimus species such as P. skrjabini, only a few of the parasites develop into adults in the lungs, while most others migrate to various organs including muscles, subcutaneous tissue, brain, liver, and so on, at the juvenile stage [9, 10]. Such ectopic infections can cause a variety of signs and symptoms including subcutaneous mass, headache, epilepsy, diarrhoea [9, 11, 12]. Probably due to its status as a NTD, suffering from paragonimiasis is often misunderstood and its quantification in the disability weight (DW) of disability-adjusted life years (DALYs) largely varies in global burden of disease (GBD) estimates. Fürst et al. [3] estimated the disease burden of paragonimiasis based on existing DWs pertaining to most similar outcomes, which were chronic outcomes of lower respiratory infection for heavy pleuropulmonary infections Table 1 DWs used in disease burden estimation Disease burden estimation Outcome Proxy health state Proxy DW Reference GBD 2016 Asymptomatic paragonimiasis N/A N/A [18] GBD 2013 Heavy paragonimiasis TB, not HIV infected 0.333 (0.224–0.454) Mild paragonimiasis due to foodborne trematodiases COPD and other chronic respiratory problem, mild 0.019 (0.011–0.033) Moderate paragonimi (...truncated)