Optimal control strategies supported by system dynamics modelling: a study on hookworm disease in China.

Abstract

Background: Hookworm disease remains a global health issue. In China, it persists with a 0.67% infection rate and uneven distribution in 2021. Optimized control strategies are needed. This study aims to optimize intervention strategies for hookworm disease in China.

Methods: Structural analysis and parameter estimation were conducted using system dynamics theory. Key variables were identified via the Delphi method, leading to the creation of a causal loop diagram (CLD) and stock flow chart (SFC). Based on the SFC, parameter estimation and quantitative relationships were established and the model was validated. A cost-effectiveness model was then integrated into the intervention mechanism model. Various intervention measures were tested in the model to determine their cost-effectiveness ratio (CER) and effectiveness. Generalized linear models were constructed from simulation data, accounting for the impact of survey sites. The results were used to develop an optimized strategy for hookworm disease control.

Results: In comparing drug treatment methods, whole population deworming (WPD) and key population deworming (KPD) showed lower CERs than examination and voluntarily deworming (EVD), saving 384.79-504.64 CNY and 354.35-506.21 CNY per infection reduced, respectively (P < 0.001). For WPD or KPD alone, CER decreased with increased drug coverage. For examination and deworming (ED) and EVD, CER was highest at 30% coverage for a 1-year intervention, but at 90% coverage for 2-5 years (P < 0.05). WPD, ED, and EVD had higher infection reduction rates than KPD, with ratios of 0.14-0.25, 0.10-0.19, and 0.08-0.17, respectively, over 1-5 years (P < 0.001). Continuous health education over 1-5 years showed that increasing coverage from a 10% baseline led to enhancing cost-effectiveness and intervention outcomes.

Conclusions: In high-endemic areas (infection rate ≥ 20%) in China, prioritize WPD for better cost-effectiveness and outcomes. In medium-endemic areas (5% ≤ infection rate < 20%) where WPD isn't feasible, use ED for cost-effectiveness and KPD for infection reduction, based on local needs. In low-endemic areas (infection rate < 5%), encourage voluntary examination and treatment due to limited cost-effectiveness of mass treatment. Combining drug treatment with extensive health education can enhance long-term control effect. This strategy can guide control efforts for hookworm diseases in China.

Clinical trial number: Not applicable.