Increasing socioeconomic inequalities in first acute myocardial infarction in Scotland, 1990-92 and 2000-02

Abstract

Background: Despite substantial declines, Ischaemic Heart Disease (IHD) remains the largest cause of death in Scotland and mortality rates are among the worst in Europe. There is evidence of strong, persisting regional and socioeconomic inequalities in IHD mortality, with the majority of such deaths being due to Acute Myocardial Infarction (AMI). We examine the changes in socioeconomic and geographic inequalities in first AMI events in Scotland and their interactions with age and gender.

Methods: We used linked hospital discharge and death records covering the Scottish Population (5.1 million). Risk ratios (RR) of AMI incidence by area deprivation and age for men and women were estimated using multilevel Poisson modelling. Directly standardised rates were presented within these stratifications.

Results: During 1990-92 74,213 people had a first AMI event and 56,995 in 2000-02. Adjusting for area deprivation accounted for 59% of the geographic variability in AMI incidence rates in 1990-92 and 33% in 2000-02. Geographic inequalities in male incidence reduced; RR for smaller areas (comparing area on 97.5th centile to 2.5th) reduced from 1.42 to 1.19. This was not true for women; RR increased from 1.45 to 1.59. The socioeconomic gradient in AMI incidence increased over time (p-value < 0.001) but this varied by age and gender. The gradient across deprivation categories for male incidence in 1990-92 was most pronounced at younger ages; RR of AMI in the most deprived areas compared to the least was 2.6 (95% CI: 1.6-4.3) for those aged 45-59 years and 1.6 (1.1-2.5) at 60-74 years. This association was also evident in women with even stronger socioeconomic gradients; RRs for these age groups were 4.4 (3.4-5.5), and 1.9 (1.7-2.2). Inequalities increased by 2000-02 for both sexes; RR for men aged 45-59 years was 3.3 (3.0-3.6) and for women was 5.6 (4.1-7.7)

Conclusion: Relative socioeconomic inequalities in AMI incidence have increased and gradients are steepest in young women. The geographical patterning of AMI incidence cannot be fully explained by socioeconomic deprivation. The reduction of inequalities in AMI incidence is key to reducing overall inequalities in mortality and must be a priority if Scotland is to achieve its health potential.

Figure 1

Age standardised AMI incidence rates by year, gender, age and deprivation. Rates are directly age standardised to the European standard population and presented per 100,000 population.

Figure 2

Socioeconomic gradients in AMI incidence rates by year, gender and age. Risk ratios and their 95% confidence intervals compare AMI incidence rates in each DEPCAT to DEPCAT 1 (reference category). DEPCAT 1 are the least deprived areas, DEPCAT 7 the most deprived.