Helminth infections in the US military: from strongyloidiasis to schistosomiasis

Cost-effectiveness of treatment strategies for populations from strongyloidiasis high-risk areas globally who will initiate corticosteroid treatment in the United States

BACKGROUND

The risk of developing strongyloidiasis hyperinfection syndrome appears to be elevated among individuals who initiate corticosteroid treatment. Presumptive treatment or treatment after screening for populations from Strongyloides stercoralis-endemic areas has been suggested before initiating corticosteroids. However, potential clinical and economic impacts of preventative strategies have not been evaluated.

METHODS

Using a decision tree model for a hypothetical cohort of 1000 individuals from S. stercoralis-endemic areas globally initiating corticosteroid treatment, we evaluated clinical and economic impacts of two interventions, 'Screen and Treat' (i.e. screening and ivermectin treatment after a positive test), and 'Presumptively Treat,' compared to current practice (i.e. 'No Intervention'). We evaluated the cost-effectiveness (net cost per death averted) of each strategy using broad ranges of pre-intervention prevalence and hospitalization rates for chronic strongyloidiasis patients initiating corticosteroid treatment.

RESULTS

For the baseline parameter estimates, 'Presumptively Treat' was cost-effective (i.e. clinically superior with cost per death averted less than a threshold of $10.6 million per life) compared to 'No Intervention' ($532 000 per death averted) or 'Screen and Treat' ($39 000 per death averted). The two parameters contributing the most uncertainty to the analysis were the hospitalization rate for individuals with chronic strongyloidiasis who initiate corticosteroids (baseline 0.166%) and prevalence of chronic strongyloidiasis (baseline 17.3%) according to a series of one-way sensitivity analyses. For hospitalization rates greater than 0.022%, 'Presumptively Treat' would remain cost-effective. Similarly, 'Presumptively Treat' remained preferred at prevalence rates of 4% or above; 'Screen and Treat' was preferred for prevalence between 2% and 4%, and 'No Intervention' was preferred for prevalence less than 2%.

CONCLUSIONS

The findings support decision-making for interventions for populations from S. stercoralis endemic areas before initiating corticosteroid treatment. Although some input parameters are highly uncertain and prevalence varies across endemic countries, 'Presumptively Treat' would likely be preferred across a range for many populations given plausible parameters.

Costs and Prescribing Patterns of Anthelmintics in the United States Military: A Retrospective Analysis

BACKGROUND

Recent price increases in medications used to treat helminth infections have had demonstrated impacts on Medicaid and immigrant patient populations. Helminth infections are common within the US military; however, anthelmintic prescribing patterns and costs have not yet been investigated in this patient population.

METHODS

We conducted a retrospective analysis of pharmaceutical data from the Military Health System Data Repository between fiscal years 2012 and 2019. Prescription information, including costs and demographics, were abstracted for all anthelmintic medications as well as associated helminth diagnostic codes within 30 days of the prescription dispensing date.

RESULTS

On average, there were 10 871 anthelmintic medications prescribed per year, for a total of 86 697 during the study period. Ivermectin and albendazole were each prescribed >34 000 times. There were 15 498 mebendazole prescriptions and 1327 praziquantel prescriptions. The total cost of all anthelmintic prescriptions was $16 018 381. Annual costs for anthelmintic medications increased 16-fold during the study period, up to nearly $5 000 000 in fiscal year 2019, primarily driven by price increases in albendazole and mebendazole. Albendazole prescriptions accounted for $12 282 891 of total costs (76.7%), though only 39.1% of total prescriptions. The most common diagnosis associated with albendazole and mebendazole prescriptions was enterobiasis.

CONCLUSIONS

Price increases in anthelmintic medications have significantly impacted the costs borne by the US government for treating parasitic infections. There are a substantial number of anthelmintic prescriptions in the US military health care system annually, suggesting a higher number of helminth infections than previously thought.

Schistosomiasis: still a neglected disease

Schistosomiasis remains an infrequent travel-related disease, mostly affecting returnees from Sub-Saharan Africa. The neglect of schistosomiasis research and development has consequences not only for endemic populations but also for travellers. Recent studies highlight deficits in clinical recognition, diagnostics and therapy of travel-related schistosomiasis, with significant morbidity, both acute and chronic.