Health Inequities in Manitoba: Is the Socioeconomic Gap

Chapter 8: Pharmaceutical Use
166 University of Manitoba
Rates by neighbourhood income quintile over time:
Rural:
• From T1 to T4, the proportion of AMI patients who filled at least one beta-blocker prescription
increased steadily across all rural neighbourhood income quintiles.
• The disparity 7 between R1 and R5 did not substantially nor significantly increase over the time
period. The rate ratio of R1 compared to R5 was 0.83 in the first time period and 0.91 in the most
recent time period, and these were not statistically significantly different. The absolute difference
gap of beta-blocker use amongst post-AMI patients was also not statistically significantly different
over time, 11.60 less patients prescribed the beta-blockers per 100 in R1 compared to R5 in T1 and
7.37 less per 100 in T4.
Urban:
• From T1 to T4, the proportion of AMI patients who filled at least one beta-blocker prescription
increased steadily across all urban neighbourhood income quintiles, although not as dramatically in
the last two time periods.
• The disparity between U1 and U5 did not substantially nor significantly increase over the time
period. The rate ratio of U1 compared to U5 was 0.86 in the first time period and 0.98 in the most
recent time period, representing a non-significant decrease of 14%. The absolute difference gap of
beta-blocker use amongst post-AMI patients significantly decreased over time by 80%, from 10.04
fewer beta-blocker users per 100 in U1 compared to U5 in the first time period compared to 1.99
fewer users per 100 in the last time period.
Lorenz Curves:
Rural over time:
• In the first time period T1, 20.7% of the post-AMI patients who were dispensed a beta-blocker
were accounted for in the 23.1% of the population in the lowest neighbourhood income quintile
group R1, with the Gini coefficient of 0.041. Although this coefficient is statistically significant, this
is a relatively minor deviation from the expected curve and should be considered as approaching
‘equality’.
• In the last time period T4, 22.5% of the post-AMI patients dispensed a beta-blocker were accounted
for in the 23.6% of the population in R1. There was no evidence of disparity as demonstrated by the
non-statistically significant Gini coefficient (i.e., the Gini coefficient’s 95% CI include 0) and the Lorenz
curve that is very similar to the line of equality.
• Comparing T1 to T4, the Gini coefficients in the rural neighbourhood income quintile groups were
not statistically significantly different (p=0.24, NS). In other words, the inequality was similar over
time and very small—close to the line of equality.
Urban over time:
• In T1, 21.9% of the post-AMI patients who were dispensed a beta-blocker were accounted for in
the 24.1% of the population in the lowest neighbourhood income quintile group U1, with a Gini
coefficient of 0.028 (not statistically significant). Thus, there appears to be no measured disparity
across urban quintiles in the first time period.
7 In the case of certain indicators where fewer events or percentages occur in the lowest compared to the highest quintile (such as
in the case of Pap tests), DRRs are below 1 and DRDs are negative—the directions of differences are somewhat non-intuitive. The
“lower” the ratio below 1 (for example, 0.7 rather than 0.8), the greater the disparity (i.e., 30% compared to 20% difference). As
well, the more negative the difference (for example, -20 compared to -10), the greater the disparity. So what appears as a positive
outcome (“lower” disparity) of lower DRRs or lower DRDs on the y-axis is actually a greater disparity.