Minnery Mark, Okoyo Collins, Morgan Grace, Wang Andrew, Johnson Olatunji, Fronterre Claudio, Montresor Antonio, Campbell Suzy J, Mwandawiro Charles, Diggle Peter
Deworm the World, Evidence Action, Washington DC, United States of America.
School of Mathematics, University of Nairobi, Nairobi, Kenya.
PLoS Negl Trop Dis. 2024 Dec 2;18(12):e0011583. doi: 10.1371/journal.pntd.0011583. eCollection 2024 Dec.
Soil-transmitted helminths (STH) and schistosomiasis comprise the most wide-spread NTDs globally. Preventative chemotherapy is a cost-effective approach to controlling morbidity of both diseases, but relies on large scale surveys to determine and revise treatment frequency. Availability of detailed information on survey costs is limited despite recent methodological surveying innovations. We micro-costed a survey of STH and schistosomiasis in Kenya, and linked results to precision estimates of competing survey methods to compare cost-efficiency.
Costs from a 2017 Kenyan parasitological survey were retrospectively analyzed and extrapolated to explore marginal changes when altering survey size, defined by the number of schools sampled and the number of samples taken per school. Subsequent costs were applied to simulated precision estimates of model-based geostatistical (MBG) and traditional survey designs. Cost-precision was calculated for a range of survey sizes per method. Four traditional survey design scenarios, based around WHO guidelines, were selected to act as reference cases for calculating incremental cost-effectiveness ratios (ICERs) for MBG design.
MBG designed surveys showed improved cost-precision, particularly if optimizing number of schools against samples per school. MBG was found to be more cost-effective under 87 of 92 comparisons to reference cases. This comprised 14 situations where MBG was both cheaper and more precise, 42 which had cost saving with precision trade off (ICERs; $8,915-$344,932 per percentage precision lost); and 31 more precise with increased cost (ICERs; $426-$147,748 per percentage precision gained). The remaining 5 comparisons represented extremes of MBG simulated site selection, unlikely to be applied in practice.
Efficiency gains are possible for deworming surveys when considering cost alone, such as through minimizing sample or analysis costs. However further efficiency maximization is possible when designing surveys using MBG given its improved precision and ability to optimize the balance between number of schools and sample size per school.
土壤传播的蠕虫病（STH）和血吸虫病是全球传播最广泛的被忽视热带病。预防性化疗是控制这两种疾病发病率的一种具有成本效益的方法，但依赖于大规模调查来确定和调整治疗频率。尽管最近在调查方法上有创新，但关于调查成本的详细信息仍然有限。我们对肯尼亚的一项土壤传播的蠕虫病和血吸虫病调查进行了微观成本核算，并将结果与竞争调查方法的精度估计联系起来，以比较成本效益。
回顾性分析了2017年肯尼亚寄生虫学调查的成本，并进行外推，以探讨在改变调查规模时的边际变化，调查规模由抽样学校数量和每所学校采集的样本数量定义。随后的成本被应用于基于模型的地质统计学（MBG）和传统调查设计的模拟精度估计。计算了每种方法在一系列调查规模下的成本精度。选择了四种基于世界卫生组织指南的传统调查设计方案，作为计算MBG设计的增量成本效益比（ICER）的参考案例。
MBG设计的调查显示出成本精度有所提高，特别是在优化学校数量与每所学校样本数量之间的平衡时。在与参考案例的92次比较中，发现MBG在87次比较中更具成本效益。其中包括14种情况，即MBG既更便宜又更精确；42种情况是在精度有所牺牲的情况下实现了成本节约（ICER；每损失一个百分点的精度，成本为8915美元至344932美元）；31种情况是精度提高但成本增加（ICER；每提高一个百分点的精度，成本为426美元至147748美元）。其余5次比较代表了MBG模拟选址的极端情况，在实际中不太可能应用。
仅考虑成本时，驱虫调查有可能提高效率，例如通过最小化样本或分析成本。然而，在使用MBG设计调查时，由于其精度提高以及能够优化学校数量和每所学校样本量之间的平衡，进一步提高效率是可能的。
