Contribution of main causes of death to social inequalities in mortality in the whole population of Scania, Sweden

Abstract

Background: To more efficiently reduce social inequalities in mortality, it is important to establish which causes of death contribute the most to socioeconomic mortality differentials. Few studies have investigated which diseases contribute to existing socioeconomic mortality differences in specific age groups and none were in samples of the whole population, where selection bias is minimized. The aim of the present study was to determine which causes of death contribute the most to social inequalities in mortality in each age group in the whole population of Scania, Sweden.

Methods: Data from LOMAS (Longitudinal Multilevel Analysis in Skåne) were used to estimate 12-year follow-up mortality rates across levels of socioeconomic position (SEP) and workforce participation in 975,938 men and women aged 0 to 80 years, during 1991-2002.

Results: The results generally showed increasing absolute mortality differences between those holding manual and non-manual occupations with increasing age, while there were inverted u-shaped associations when using relative inequality measures. Cardiovascular diseases (CVD) contributed to 52% of the male socioeconomic difference in overall mortality, cancer to 18%, external causes to 4% and psychiatric disorders to 3%. The corresponding contributions in women were 55%, 21%, 2% and 3%. Additionally, those outside the workforce (i.e., students, housewives, disability pensioners, and the unemployed) showed a strongly increased risk of future mortality in all age groups compared to those inside the workforce. Even though coronary heart disease (CHD) played a major contributing role to the mortality differences seen, stroke and other types of cardiovascular diseases also made substantial contributions. Furthermore, while the most common types of cancers made substantial contributions to the socioeconomic mortality differences, in some age groups more than half of the differences in cancer mortality could be attributed to rarer cancers.

Conclusion: CHD made a major contribution to the socioeconomic differences in overall mortality. However, there were also important contributions from diseases with less well understood mechanistic links with SEP such as stroke and less-common cancers. Thus, an increased understanding of the mechanisms connecting SEP with more rare causes of disease might be important to be able to more successfully intervene on socioeconomic differences in health.

Figure 1

Proportional (%) specific causes of death among men and women inside the workforce holding non-manual or manual occupations in Scania, Sweden. International Classification of Diseases (ICD) codes; cardiovascular disease (codes 390 to 459 (ICD 8^th and 9^th version) or I00 to I99 (ICD-10^th version)), cancer (140 to 239 (ICD 8^th and 9^th version) or C00 to D48 (ICD-10^th version)), psychiatric diseases (290 to 319 (ICD 8^th and 9^th version) or F00 to F99 (ICD-10^th version)), external causes (800 to 999 (ICD 8^th and 9^th version) or S00 to T98 and V01 to Y98 (ICD-10^th version)), infectious diseases (000 to 139 (ICD 8^th and 9^th version) or A00 to B99 (ICD-10^th version)), and COPD (490 to 496 (ICD 8^th and 9^th version) or J40 to J47 (ICD-10^th version)).

Figure 2

Proportional (%) specific causes of death in the whole population of men and women in Scania, Sweden. International Classification of Diseases (ICD) codes; cardiovascular disease (codes 390 to 459 (ICD 8^th and 9^th version) or I00 to I99 (ICD-10^th version)), cancer (140 to 239 (ICD 8^th and 9^th version) or C00 to D48 (ICD-10^th version)), psychiatric diseases (290 to 319 (ICD 8^th and 9^th version) or F00 to F99 (ICD-10^th version)), external causes (800 to 999 (ICD 8^th and 9^th version) or S00 to T98 and V01 to Y98 (ICD-10^th version)), infectious diseases (000 to 139 (ICD 8^th and 9^th version) or A00 to B99 (ICD-10^th version)), and COPD (490 to 496 (ICD 8^th and 9^th version) or J40 to J47 (ICD-10^th version)).

Figure 3

Age-adjusted relative difference measured as hazard rate ratios (HRR) in all-cause mortality between those holding non-manual occupations, those holding manual occupations and those outside the workforce, in Scania, Sweden. Those holding non-manual occupations were used as the reference. Variations by age and sex are presented.

Figure 4

Absolute difference in all-cause mortality rate per 100 000 person-years between those holding non-manual occupations, those holding manual occupations and those outside the workforce, in Scania, Sweden. Those holding non-manual occupations were used as the reference group. Variations by age and sex are presented.