Abstract

Methods

Results

The final sample for our study included 19 370 individuals (Table 1). People who identified themselves as white were older, wealthier, less healthy and less likely to have recently immigrated to Canada than people who were of non-white ethnic backgrounds. Respondents of mixed ethnicity (85% of whom replied yes to “white” and a visible minority group) were younger, wealthier and less likely to be a recent immigrant than those of a single ethnic group.

Open in a separate window

Table 1

Descriptive statistics of study sample

Crude rates of diagnoses of conditions for which the selected drug classes are indicated varied by ethnic group, the largest variation being observed for diagnoses for which antidepressants are indicated. White women, white men and south Asian men had the highest sex-specific prevalence of conditions for which antihypertensives are commonly indicated. South Asian men had the highest prevalence of conditions for which antibiotics, statins, NSAIDs and respiratory drugs are commonly indicated. South Asian women had the highest prevalence of conditions for which antibiotics and NSAIDs are commonly indicated. Women who were in either the white or the non-Asian, non-white ethnic groups and men of mixed ethnicity had the highest prevalence of conditions for which antidepressants are commonly indicated. Crude rates of antihypertensive, antidepressant and statin use were highest among white women and men; crude rates of antibiotic and NSAID use were highest among South Asian women and men. Crude rates of respiratory drug use were highest among white women and South Asian men. After adjustment for age, general health status (using counts of ADGs), condition-specific indications (using specific EDCs), socio-economic factors and recent immigration, several ethnic differences in the use of prescription drugs remained. Table 2 lists adjusted odds ratios (ORs) for the likelihood of filling prescriptions for antihypertensives, antibiotics, antidepressants, statins, respiratory drugs and NSAIDS by ethnic group. For antihypertensive prescriptions, Chinese women were about half as likely as white women to fill them (OR 0.46, 95% confidence interval [CI] 0.32–0.65). Chinese men were less likely than white men to fill antihypertensive prescriptions, although the difference was not significant (OR 0.74, 95% CI 0.52–1.06). None of the other ethnic differences in the odds of filling prescriptions for antihypertensives were statistically significant. Chinese women and non-Asian, non-white women had significantly lower odds of filling prescriptions for antibiotics than white women. South Asian men were significantly more likely than white men to fill antibiotic prescriptions (OR 1.57, 95% CI 1.16–2.12), while men of “other Asian” background were less likely to fill them (OR 0.67, CI 0.46–0.97). For antidepressant prescriptions, several ethnic groups (most significantly Chinese women and men, but also other Asian women and men, and non-Asian, non-white women) were significantly less likely than white women and men to fill them.

Open in a separate window

Table 2

Adjusted odds ratios for the likelihood of filling prescriptions, by drug class and self-identified ethnicity

Table 2 lists adjusted odds ratios for the likelihood of filling prescriptions for statins, respiratory drugs and NSAIDs by ethnic group. Chinese women were significantly less likely than white women to fill prescriptions for respiratory medicines (OR 0.37, 95% CI 0.22–0.62). For NSAID prescriptions, South Asian women and men were more likely than white women and men to fill them (women: OR 1.46, 95% CI 1.03–2.08; men: OR 1.61, 95% CI 1.13–2.31).

Interpretation

Using linked survey and administrative data, we found statistically significant ethnic differences in the use of prescription drugs among non-Aboriginal residents in urban areas of British Columbia, even after adjusting for age, health status, socio-economic factors and recent immigration. Compared with respondents who were white, those who were South Asian or of mixed ethnicity were about as likely to fill prescriptions for most classes of medicines studied; however, South Asian men were significantly more likely to fill prescriptions for antibiotics and NSAIDs. Although a dominant pattern is difficult to determine because ethnic differences in presciption drug use appear to vary across therapeutic categories, there are nevertheless some important disparities. Chinese women were less likely than white women to fill prescriptions for antihypertensives, antibiotics, antidepressants and respiratory drugs. Chinese men were less likely than white men to fill prescriptions for statins and antidepressants. Overall, ethnic disparities were greater among women than among men, which suggests that gender roles, relationships and institutions may modify the effects of ethnicity on patient or provider behaviour.

Although rates of prescription drug use are lower in British Columbia than in other provinces,²² we believe that the ethnic differences identified in our study are likely representative of disparities among ethnic populations in urban areas across Canada. Moreover, the results of our study are generally consistent with previous research from the United States and Europe, which showed that ethnic groups use prescription drugs less frequently than white people.^9-12 Two findings from our study stand out from the literature on prescription drug use: the increased use of antibiotics by South Asian men compared with white men and the increased use of NSAIDs by South Asian woman and men compared with white women and men. However, there is evidence of a higher prevalence of reported pain among South Asian groups than among white people, which may explain these patterns.²³

Differences in the use of prescription drugs across ethnic groups may have resulted from differences in access to medical care,^4-8 burdens of illness,^24-25 beliefs about medicines¹⁵ or communications with practitioners.²⁶ The pattern of findings across the drug classes we studied suggests that some differences may stem from beliefs and preferences about the use of prescription drugs versus other treatment options (including herbal medicines).²⁷ We found the greatest degree of ethnic variation in the use of antidepressants, a drug class for which cultural beliefs about health and treatment are likely to affect patient choices.¹⁵ Patients of different ethnic backgrounds who have depression or anxiety may present differently; immigrants to Canada may also choose to seek care through other sources, including importing medicines during visits to their country of birth.²⁸ It is potentially encouraging that differences in the use of antihypertensives and statins were smaller than differences in the use of other classes of drugs; nevertheless, there appear to be ethnic differences of potential clinical significance in such essential drug classes, particularly for Chinese people. The source of such differences may not be limited to patient preference: a telephone survey of residents in Vancouver (the largest urban area of British Columbia) found that Chinese immigrants to Canada were less likely than people of other ethnic backgrounds to receive patient education about heart disease from their health care providers.²⁶

Our study has limitations. Although we were able to link data on self-reported ethnic identities with administrative data on filled prescriptions, quantitative analysis of observational data can provide only a generalized account of the complex personal and social dimensions of ethnicity.²⁹ Our measure of prescription drug use was based on filled prescriptions, with no guarantee that the medicines were actually taken. Moreover, some prescriptions may not be filled by patients owing to cost, beliefs or other reasons. Some of the ethnic differences in the use of prescription drugs in our study may therefore have been due to differences in the rates of prescriptions filled by patients, not to differences in the rates of prescriptions written by practitioners.

The use of administrative data also limits diagnostic information to that documented during encounters for medical and hospital services. Our methods may therefore understate the level of health care needs for groups who experience economic, cultural or other demonstrable barriers to health care. Given that our primary finding was that the use of prescription drugs was lower among ethnic minorities who may use fewer health services, the bias from underreporting health care needs would tend to understate the extent of needs-adjusted ethnic disparities.

Having pooled CCHS data across multiple years, we were unable to use information on self-reported health status and health care use from the survey, because such measures are not time-invariant. We were, however, able to link data on self-reported ethnicity to administrative health care data that are not subject to recall or social-desirability bias that might otherwise affect measurement of health care needs and prescription drug use. The linkage of 3 cycles of the CCHS data to administrative records produced a sample that, despite having a higher percentage of ethnic minorities than samples of the CCHS used in other studies,⁸ underrepresents immigrants and non-white ethnic groups in British Columbia compared with census data.² A larger, linkable source of ethnicity data might have reduced confidence intervals around point estimates and thereby resulted in statistical significance of ethnic variations that appeared clinically important but not statistically significant in the present study (e.g., use of antihypertensives and statins by South Asian people).

Conclusion

Despite a relatively equitable system of health care financing in Canada, there appear to be significant ethnic differences in prescription drug use. Some of these differences, such as marked variation in the use of antidepressants, may reflect acceptable differences resulting from patient preferences and beliefs; others may reflect unacceptable inequities in quality of care and resulting outcomes. Further research is needed to separate the former from the latter. The differences in patterns of prescription drug use that we observed across ethnic groups suggest that simple comparisons between white people and a single “visible minority” group should be avoided whenever possible in future research. Moreover, our sex-specific findings suggest that gender and ethnicity interact in ways that are potentially important for health care practice and policy. To address these important issues with quality scientific evidence, more routine collection of, and research into, information concerning ethnicity and health care in Canada will be required.

Appendix

Appendix A

Open in a separate window

Details of sample selection

Appendix B

Drug types and diagnoses included, by therapeutic categories studied

Click here to view.^{(196K, pdf)}

Appendix C

Ethnic groups derived from the Canadian Community Health Survey (CCHS) data

Click here to view.^{(174K, pdf)}

Footnotes

References