Self-rated health. Comparisons between three different measures. Results from a population study.

BACKGROUND: Self-rating of health is among the most frequently assessed health perceptions in epidemiological research. The aim of this study was to compare different measures of global self-rated health (SRH) with respect to differences in age and sex groups and relations to hypothesized determinants.
METHOD: Three single-question measures of SRH were included in a health questionnaire administered to 8200 randomly chosen men and women. Two SRH measures were non-comparative, one with seven (SRH-7) and one with five response options (SRH-5), while the third measure included a comparison with others of the same age (SRH-age). SRH-7 had specified response options only at the ends of the scale, while the other two measures gave specified statements for each option. Comparisons between the SRH assessments were studied with respect to response frequencies, frequency distributions, age and gender differences and differences in associations with hypothesized determinants.
RESULTS: The differences between the SRH measures were in most cases marginal. Some diversities may, however, be worth considering: a high drop-out rate for the SRH-7 measure in the oldest age group; a trend that SRH-7 correlated most strongly with the independent variables; SRH-age showed improved health ratings with increasing age but a less skewed frequency distribution compared to the non-comparative measures.
CONCLUSIONS: The results imply that non-comparative measures are more appropriate in longitudinal studies and that measures without specified response options might be less suitable for an older study group. The overall impression is, however, that the different measures represents parallel assessments of subjective health.