Cost and cost-effectiveness of soil-transmitted helminth treatment programmes: systematic review and research needs

Abstract

Background: In this time of rapidly expanding mass drug administration (MDA) coverage and the new commitments for soil-transmitted helminth (STH) control, it is essential that resources are allocated in an efficient manner to have the greatest impact. However, many questions remain regarding how best to deliver STH treatment programmes; these include which age-groups should be targeted and how often. To perform further analyses to investigate what the most cost-effective control strategies are in different settings, accurate cost data for targeting different age groups at different treatment frequencies (in a range of settings) are essential.

Methods: Using the electronic databases PubMed, MEDLINE, and ISI Web of Knowledge, we perform a systematic review of costing studies and cost-effectiveness evaluations for potential STH treatment strategies. We use this review to highlight research gaps and outline the key future research needs.

Results: We identified 29 studies reporting costs of STH treatment and 17 studies that investigated its cost-effectiveness. The majority of these pertained to programmes only targeting school-aged children (SAC), with relatively few studies investigating alternative preventive chemotherapy (PCT) treatment strategies. The methods of cost data collection, analysis and reporting were highly variable among the different studies. Only four of the costing studies were found to have high applicability for use in forthcoming economic evaluations. There are also very few studies quantifying the costs of increasing the treatment frequency.

Conclusions: The absence of cost data and inconsistencies in the collection and analysis methods constitutes a major research gap for STH control. Detailed and accurate costs of targeting different age groups or increasing treatment frequency will be essential to formulate cost-effective public health policy. Defining the most cost-effective control strategies in different settings is of high significance during this period of expanding MDA coverage and new resource commitments for STH control.

Fig. 1

Decision tree outlining the inclusion and exclusion of the identified studies; * Several studies reported both costs and cost-effectiveness estimates. A PRISMA checklist is provided in Additional file 2

Fig. 2

The number of identified costs for STH treatment stratified by the target age group and the method of distribution. Pre-SAC; Pre-school aged children, SAC; School aged children. School-based delivery systems were defined as those utilising teachers and other school officials (not just distributing the drugs at the school). A combination strategy was defined as using both the school system and community drug distributers (CDDs). Some studies were counted more than once, as the target population was varied within the study. * Targeted adults (such as those in at risk occupations); ǂ Programme also targeting lymphatic filariasis (LF)

Fig. 3

Distribution of the published costing studies over time stratified by the method of distribution. School-based delivery systems were defined as those utilising teachers and other school officials (not just distributing the drugs at the school). A combination strategy was defined as those using both the school system and community drug distributers (CDDs)

Fig. 4

The number of identified costs for STH control, stratified by treatment frequency and the method of distribution. School-based delivery systems were defined as those utilising teachers and other school officials (not just distributing the drugs at the school). A combination strategy was defined as those using both the school system and community drug distributers (CDDs). Studies that just reported the costs of one treatment round were classed as annual. Some studies were counted more than once as the treatment frequency was varied within the study

Fig. 5

Observed economies of scale associated with mass drug administration (MDA). Data from a: Brooker et al. [24], b: Evans et al. [20]

Fig. 6

The number of identified cost-effectiveness estimates of STH control, stratified by target population and method of distribution. Pre-SAC; Pre-school aged children, SAC; School aged children. School-based delivery systems were defined as those utilising teachers and other school officials (not just distributing the drugs at the school). A combination strategy was defined as using both the school system and community drug distributers (CDDs). Some studies were counted more than once as the target population was varied within the study. *Targeted adults (such as those in at risk occupations)