Socioeconomic inequalities in musculoskeletal disorders outcomes and care. Educational inequalities in fracture-related mortality and osteoarthritis.
Author
Summary, in English
Musculoskeletal disorders (MSDs) are a major cause of disability worldwide, and two conditions that are major contributors to the overall burden of MSDs are fractures and osteoarthritis (OA). The Swedish Health and Medical Services Act (HSL 2017:30) states that the goal of all health care services is good health and health care on equal terms for the entire population. However, there exists a well-known association between SES and health, where people with lower SES, generally, tend to have poorer health and higher mortality. This association is seen for a wide range of diseases, including MSDs. However, the knowledge about inequalities in MSDs in the Swedish health care system is limited. Thus, the aim of this thesis was to determine the association between SES and outcomes in MSDs, with focus on fractures and osteoarthritis, in order to identify potential health inequalities.
The studies in this thesis are based on individual-level register data from people resident in the Skåne region (study I and II) and the whole country of Sweden (study III and IV). Study I-III are open cohort studies, while study IV has a repeated cross-sectional design. In addition, study I and III have a multiple cause of death approach and co-twin control design, respectively. Educational attainment was used as an indicator for SES in all studies. Following data sources were used: Statistics Sweden, The National Board of Health and Welfare, The Skåne Healthcare Register, The Swedish Twin Registry (STR), and The Swedish Military Conscription Registry.
In study I, absolute and relative educational inequalities in non-hip and hip fracture-related mortality were examined using the slope index of inequality (SII) and relative index of inequality (RII), respectively. The study period was between 1998-2014, and 999,148 people were included. Generally, the absolute as well as the relative inequalities revealed higher fracture-related mortality in people with low vs. high education, suggesting that preventative and therapeutic interventions of fractures in low educated people should be targeted.
Study II assessed the association between education and all-cause and cause-specific mortality among patients with OA (123,993 people) in comparison to an OA-free reference cohort (121,318 people). The study period was from 1998 to 2014, and the inequalities were examined with SII and RII. The results showed that people with lower education, with or without OA, have higher all-cause and cause-specific mortality and that the inequalities observed in OA patients reflect the health inequalities in the population at large. In addition, the results suggest that OA patients, especially with lower education, have a greater burden of cardiovascular diseases, which implies that it is important to focus on the prevention and treatment of cardiovascular diseases in this group.
The aim of study III was to examine the association between educational attainment and knee and hip OA surgery using twin data. In total, 67,071 twins from the STR were included and the studied time period was between 1987-2016. The main analysis was Weibull within-between shared frailty model. When adjusting for genetics and early-life environment, there was no association between educational attainment and knee and hip OA surgery. However, a confounding familial effect in the association between educational attainment and knee OA surgery was found.
In study IV changes in prevalence and socioeconomic inequalities in knee and hip OA surgery and non-surgery specialist care visits were examined. The studied time period was 2001-2011, and the prevalence and inequalities were estimated for each year. The concentration Index was used to assess relative and absolute inequalities. The Blinder-Oaxaca decomposition method was used to examine the factors contributing to the changes between the years 2001 (4 794,693 people) and 2011 (5 359,186 people). The prevalence of all outcomes rose. Changes in the strength of the association between sociodemographic factors and OA outcomes contributed the most to the increase in knee OA outcomes. For hip OA outcomes, the increase was primarily due to changes in the characteristics of the populations over time. All outcomes were more concentrated among people with lower education. Absolute educational inequalities were either decreasing or steady over time, while there was a declining tendency in relative inequalities for all outcomes.
The overall conclusion of the thesis is that there are socioeconomic inequalities in fracture-related mortality and OA-related outcomes in favour of people with higher SES. The associations need to be investigated in more detail in order to be able to reduce the observed differences.
The studies in this thesis are based on individual-level register data from people resident in the Skåne region (study I and II) and the whole country of Sweden (study III and IV). Study I-III are open cohort studies, while study IV has a repeated cross-sectional design. In addition, study I and III have a multiple cause of death approach and co-twin control design, respectively. Educational attainment was used as an indicator for SES in all studies. Following data sources were used: Statistics Sweden, The National Board of Health and Welfare, The Skåne Healthcare Register, The Swedish Twin Registry (STR), and The Swedish Military Conscription Registry.
In study I, absolute and relative educational inequalities in non-hip and hip fracture-related mortality were examined using the slope index of inequality (SII) and relative index of inequality (RII), respectively. The study period was between 1998-2014, and 999,148 people were included. Generally, the absolute as well as the relative inequalities revealed higher fracture-related mortality in people with low vs. high education, suggesting that preventative and therapeutic interventions of fractures in low educated people should be targeted.
Study II assessed the association between education and all-cause and cause-specific mortality among patients with OA (123,993 people) in comparison to an OA-free reference cohort (121,318 people). The study period was from 1998 to 2014, and the inequalities were examined with SII and RII. The results showed that people with lower education, with or without OA, have higher all-cause and cause-specific mortality and that the inequalities observed in OA patients reflect the health inequalities in the population at large. In addition, the results suggest that OA patients, especially with lower education, have a greater burden of cardiovascular diseases, which implies that it is important to focus on the prevention and treatment of cardiovascular diseases in this group.
The aim of study III was to examine the association between educational attainment and knee and hip OA surgery using twin data. In total, 67,071 twins from the STR were included and the studied time period was between 1987-2016. The main analysis was Weibull within-between shared frailty model. When adjusting for genetics and early-life environment, there was no association between educational attainment and knee and hip OA surgery. However, a confounding familial effect in the association between educational attainment and knee OA surgery was found.
In study IV changes in prevalence and socioeconomic inequalities in knee and hip OA surgery and non-surgery specialist care visits were examined. The studied time period was 2001-2011, and the prevalence and inequalities were estimated for each year. The concentration Index was used to assess relative and absolute inequalities. The Blinder-Oaxaca decomposition method was used to examine the factors contributing to the changes between the years 2001 (4 794,693 people) and 2011 (5 359,186 people). The prevalence of all outcomes rose. Changes in the strength of the association between sociodemographic factors and OA outcomes contributed the most to the increase in knee OA outcomes. For hip OA outcomes, the increase was primarily due to changes in the characteristics of the populations over time. All outcomes were more concentrated among people with lower education. Absolute educational inequalities were either decreasing or steady over time, while there was a declining tendency in relative inequalities for all outcomes.
The overall conclusion of the thesis is that there are socioeconomic inequalities in fracture-related mortality and OA-related outcomes in favour of people with higher SES. The associations need to be investigated in more detail in order to be able to reduce the observed differences.
Department/s
Publishing year
2023
Language
English
Publication/Series
Lund University, Faculty of Medicine Doctoral Dissertation Series
Issue
2023:8
Full text
Document type
Dissertation
Publisher
Lund University, Faculty of Medicine
Topic
- Public Health, Global Health, Social Medicine and Epidemiology
Keywords
- Education
- Sweden
- Osteoarthritis surgery
- Mortality
- Osteoarthritis
- Health inequities
- Fracture
Status
Published
Research group
- Lund OsteoArthritis Division - Clinical Epidemiology Unit
ISBN/ISSN/Other
- ISSN: 1652-8220
- ISBN: 978-91-8021-377-6
Defence date
31 March 2023
Defence time
09:00
Defence place
Segerfalksalen, BMC A10, Sölvegatan 17 i Lund
Opponent
- Alma Becic Pedersen (professor)