Volume 365, Issue 9470, 30 April–6 May 2005, Pages 1561–1569
Reassessment of the cost of chronic helmintic infection: a meta-analysis of disability-related outcomes in endemic schistosomiasis
- Charles H King, a,
, 
, - Katherine Dickman, a,
- Daniel J Tisch, a
- a Center for Global Health and Diseases, Wolstein 4126, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-7286, USA
- Available online 29 April 2005
- Refers To
- Extending the benefits of deworming for development
- The Lancet, Volume 365, Issue 9470, 30 April–6 May 2005, Pages 1520-1521
PDF (100 K)- Referred to by
- Extending the benefits of deworming for development
- The Lancet, Volume 365, Issue 9470, 30 April–6 May 2005, Pages 1520-1521
Summary
Background
Schistosomiasis is one of the world's most prevalent infections, yet its effect on the global burden of disease is controversial. Published disability-adjusted life-year (DALY) estimates suggest that the average effect of schistosome infection is quite small, although this is disputed. To develop an evidenced-based reassessment of schistosomiasis-related disability, we did a systematic review of data on disability-associated outcomes for all forms of schistosomiasis.
Methods
We did structured searches using EMBASE, PUBMED, and Cochrane electronic databases. Published bibliographies were manually searched, and unpublished studies were obtained by contacting research groups. Reports were reviewed and abstracted independently by two trained readers. All randomised and observational studies of schistosomiasis morbidity were eligible for inclusion. We calculated pooled estimates of reported disability-related effects using weighted odds ratios for categorical outcomes and standardised mean differences for continuous data.
Findings
482 published or unpublished reports (March, 1921, to July, 2002) were screened. Of 135 selected for inclusion, 51 provided data for performance-related symptoms, whereas 109 reported observed measures of disability-linked morbidities. Schistosomiasis was significantly associated with anaemia, chronic pain, diarrhoea, exercise intolerance, and undernutrition.
Interpretation
By contrast with WHO estimates of 0·5% disability weight assigned to schistosomiasis, 2–15% disability seems evident in different functional domains of a person with schistosomiasis. This raised estimate, if confirmed in formal patient-preference studies, indicates a need to reassess our priorities for treating this silent pandemic of schistosomiasis.
Figures and tables from this article:
Figure 1. Flow diagram, showing selection of studies
Figure 2. Forest plot of the effect of schistosomiasis infection on anaemia, measured by haemoglobin concentrationStandardised mean differences less than zero indicate lower concentrations of haemoglobin in individuals with infection than in individuals without infection. Diamonds represent pooled estimates across grouped studies (eg, across species of infection). The lowest diamond indicates the overall pooled estimate of the effect of schistosomiasis infection on anaemia. See webtable 1 for full references.
Figure 3. Forest plot of the effect of schistosomiasis treatment on haemoglobin concentrationStandardised mean differences greater than zero indicate higher concentrations of haemoglobin in treated individuals. Diamonds represent pooled results across grouped studies (eg, across species of infection). The lowest diamond indicates the overall pooled estimate of the effect of specific antischistosomal treatment on anaemia. See webtable 1 for full references.
Figure 4. Forest plot of the effect of schistosomiasis infection intensity on anaemia, measured by haemoglobin concentrationStandardised mean differences less than zero indicate lower concentrations of haemoglobin in individuals with heavy infection than in individuals with light infection. Diamonds represent pooled results across grouped studies (eg, across species of infection). The lowest diamond indicates the overall pooled estimate of the effect of infection intensity on anaemia. See webtable 1 for full references.
Figure 5. Diagram of proposed pathways of schistosomiasis-associated disease and disability
Table 1. Summary estimates of the effect of schistosomiasis or heavy schistosomiasis in terms of disability-related continuous outcomes*
Data are standardised mean difference (95% CI) and number of studies.
- View Within Article
Table 2. Summary estimates of the effect of schistosomiasis or heavy schistosomiasis by disability-related outcomes
Data are odds ratios (95% CI) and number of studies.
- View Within Article
- Correspondence to: Dr Charles H King
Copyright © 2005 Elsevier Ltd. All rights reserved.
