Reassessment of the cost of chronic helmintic infection: a meta-analysis of disability-related outcomes in endemic schistosomiasis.
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 Published bibliographies were manually searched, and unpublished studies were obtained by contacting research groups.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.


RESULTS
482 published or unpublished reports (March, 1921, to July, 2002) were screened.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.


CONCLUSIONS
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.
King
Charles H
CH
Center for Global Health and Diseases, Wolstein 4126, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-7286, USA. chk@cwru.edu
Dickman
Katherine
K
Tisch
Daniel J
DJ
D000740:Anemia / Q000209:etiology; D002908:Chronic Disease; D017281:Cost of Illness; D003967:Diarrhea / Q000209:etiology; D004185:Disability Evaluation; D004522:Educational Status; D019353:Endemic Diseases / Q000191:economics; D006801:Humans; D044342:Malnutrition / Q000209:etiology; D010809:Physical Fitness; D019057:Quality-Adjusted Life Years; D012552:Schistosomiasis / Q000150:complications / Q000188:drug therapy / Q000191:economics* / Q000453:epidemiology