PMI VectorWorks Project, Tropical Health LLP, Montagut, Spain.
PMI VectorWorks Project, Tropical Health LLP, Abuja, Nigeria.
Malar J. 2021 Jan 7;20(1):29. doi: 10.1186/s12936-020-03570-5.
Attempts have been made to link procurement of long-lasting insecticidal nets (LLIN) not only to the price but also the expected performance of the product. However, to date it has not been possible to identify a specific textile characteristic that predicts physical durability in the field. The recently developed resistance to damage (RD) score could provide such a metric. This study uses pooled data from durability monitoring to explore the usefulness of the RD methodology.
Data from standardized, 3-year, prospective LLIN durability monitoring for six LLIN brands in 10 locations and four countries involving 4672 campaign LLIN were linked to the RD scores of the respective LLIN brands. The RD score is a single quantitative metric based on a suite of standardized textile tests which in turn build on the mechanisms of damage to a mosquito net. Potential RD values range from 0 to 100 where 100 represents optimal resistance to expected day-to-day stress during reasonable net use. Survival analysis was set so that risk of failure only started when nets were first hung. Cox regression was applied to explore RD effects on physical survival adjusting for known net use environment variables.
In a bivariate analysis RD scores showed a linear relationship with physical integrity suggesting that the proportion of LLIN with moderate damage decreased by 3%-points for each 10-point increase of the RD score (p = 0.02, R = 0.65). Full adjustment for net care and handling behaviours as well as other relevant determinants and the country of study showed that increasing RD score by 10 points resulted in a 36% reduction of risk of failure to survive in serviceable condition (p < 0.0001). LLINs with RD scores above 50 had an additional useful life of 7 months.
This study provides proof of principle that the RD metric can predict physical durability of LLIN products in the field and could be used to assess new products and guide manufacturers in creating improved products. However, additional validation from other field data, particularly for next generation LLIN, will be required before the RD score can be included in procurement decisions for LLINs.
人们试图将长效杀虫蚊帐（LLIN）的采购不仅与价格联系起来，还与产品的预期性能联系起来。然而，迄今为止，还不可能确定一个特定的纺织特性可以预测现场的物理耐久性。最近开发的抗损坏（RD）评分可能提供这样的指标。本研究使用耐用性监测的汇总数据来探索 RD 方法的有用性。
将来自六个 LLIN 品牌在 10 个地点和四个国家进行的为期 3 年的标准化前瞻性 LLIN 耐用性监测的数据与各自 LLIN 品牌的 RD 评分相关联。RD 评分是一个基于一套标准化纺织测试的单一定量指标，这些测试又建立在蚊帐损坏机制的基础上。潜在的 RD 值范围从 0 到 100，其中 100 表示在合理使用蚊帐期间对日常压力具有最佳的抵抗力。生存分析设置为只有当蚊帐首次悬挂时，才开始出现故障风险。应用 Cox 回归来探索 RD 对物理生存的影响，同时调整已知的蚊帐使用环境变量。
在二元分析中，RD 评分与物理完整性呈线性关系，这表明随着 RD 评分每增加 10 分，中度损坏的 LLIN 比例减少 3 个百分点（p=0.02，R=0.65）。充分调整蚊帐护理和处理行为以及其他相关决定因素和研究国家表明，RD 评分增加 10 分可使服务状态下的故障风险降低 36%（p<0.0001）。RD 评分高于 50 的 LLIN 具有额外 7 个月的有用寿命。
本研究提供了原理证明，即 RD 指标可以预测现场 LLIN 产品的物理耐久性，并可用于评估新产品并指导制造商制造改进产品。然而，在 RD 评分可以纳入 LLIN 采购决策之前，还需要来自其他现场数据的额外验证，特别是对于下一代 LLIN。
