Objective: To assess the interrelationships between self-rated health, perceptions of long-term illness and diagnoses of chronic diseases.
Methods: In the World Health Survey, carried out in Brazil in 2003, 5,000 individuals aged 18 years and over who had been selected from a three-stage stratified sample were interviewed. The original questionnaire was adapted for the Brazilian context. It covered the presence of long-term illness or disability, self-rating of health (general and in several domains) and diagnoses of six chronic diseases (arthritis, angina, asthma, depression, schizophrenia and diabetes mellitus). To compare the relationships between self-rated health, perceptions of long-term illness and the chronic diseases evaluated, the statistical test of homogeneity of proportions and multiple logistic regression models were used.
Results: Self-rating of health as "not good" and perceptions of having long-term illnesses were significantly more frequent among women, individuals aged 50 years and over and individuals with one or more of the diseases investigated. The interviewees with a diagnosis of diabetes mellitus presented the worst self-rated health: 70.9% reported having a long-term illness and 79.3% considered that their health was "not good". Worse health ratings were found when two or more diseases were present together. The effect of self-rating of health on the perceptions of long-term illness was stronger than was the number of diseases.
Conclusions: The three ways of measuring morbidity presented significant interrelationships. Self-rating of health as "not good" had a more important effect on the perceptions of long-term illness, thus suggesting that subjective measurements of health status may be more sensitive for establishing and monitoring individuals' wellbeing.