In this study, investigators looked at over 300,000 imaging procedures in Winnipeg over a 1 year period. Unexpectedly, rates of diagnostic imaging were almost always higher in the highest income groups. Compared with patients in the lowest-income categories, patients in the highest-income groups were much more likely to receive general radiology, ultrasound, MRIs and CTs.
The relative higher frequencies of access to these procedures among higher-income individuals held for all age groups and for all but a few procedures. Only for obstetric ultrasound were rates of use for women in the lowest-income group higher than those for women in the highest-income group. All of these comparisons took into account the patient's level of illness (morbidity). The differences in rates of utilization varied, but of 36 analyses, 21 were significant; in 8 of the significant analyses, utilization rates were more than twice as high in the highest-income groups, and these tended to occur in patient groups who were most ill.
This study has important implications for social policy in Canada, and by extension to other countries with universal health care policies and social goals.
The study is limited by the fact that it was done in a single city. Access to diagnostic imaging is dependent on the availability and distribution of equipment and personnel, on the management of wait lists, and on other factors that influence access to health care, such as the density of primary care physicians per population and patterns of medical practice and referral.
Nonetheless, the large sizes of the differences in access make this an important study.
http://www.cmaj.ca/misc/press/pg1173.pdf
p. 1173 Socioeconomic status and the utilization of diagnostic imaging in an urban setting-- S. Demeter et al
Canadian Medical Association Journal