Chagas' disease and social security: a case-control study in an urban area, Goiás, Brazil

one hundred and twenty subjects with chagas' cardiopathy and 120 non-infected subjects were randomly selected from first time claimants of sickness benefits in the national institute of social security (inps) in goiás. cases of chagas' cardiopathy were defined based on serological test, history of residence in an endemic area and, clinical and/or electrocardiogram (ecg) alterations suggestive of chagas' cardiomyopathy. controls were defined as subjects with at least two negative serological tests. case and controls were compared in the analysis for age, sex, place of birth, migration history, socio-economic level, occupation, physical exertion at work, age at affiliation and years of contribution to the social security scheme, clinical course of their disease and ecg abnormalities. chagas' disease patients were younger than other subjects and predominantly of rural origin. non-infected subjects presented a better socio-economic level, were performing more skilled activities and had less changes of job than cases. no important difference was observed in relation to age at affiliation to inps. about 60% of cases have claimed for benefits within the first four years of contribution while among controls this proportion was 38.5%. cases were involved, proportionally more than controls, in "heavy" activities. a risk of 2.3 (95%cl 1.5 - 4.6) and 1.8 (95%cl 1.2- 3.5) was obtained comparing respectively "heavy" and "moderate" physical activity against "light". a relative risk of 8.5 (95%cl 4.9 - 14.8) associated with the presence of cardiopathy was estimated comparing the initial sample of seropositive subjects and controls. a high relative risk was observed in relation to right bundle branch block (rr = 37.1 95%cl = 8.8 - 155.6) and left anterior hemiblock (rr = 4.4, 95%cl = 2.1 - 9.1).