Changes in educational inequalities in knee and hip osteoarthritis surgery and non-surgery specialist care visits over time in Sweden.

Objective: To examine changes in prevalence and socioeconomic inequalities in knee and hip OA outcomes, in more specific surgery and non-surgery specialist care visits, from 2001 to 2011 in Sweden and to what extent sociodemographic factors can explain the changes. Design: We included all individuals aged ≥35 years resident in Sweden from 2001 to 2011. Individual-level data was retrieved from the Swedish Interdisciplinary Panel. Highest educational attainment was used as socioeconomic measure and the concentration index was used to assess relative and absolute educational inequalities. We used decomposition method to examine changes in prevalence and relative educational inequalities. Results: A total of 4,794,693 and 5,359,186 people were included for the years 2001 and 2011, respectively. The crude prevalence of surgery and specialist visits for knee and hip OA was 36-83% higher in 2011 than in 2001. The increase in hip OA outcomes was largely explained by changes in the sociodemographic composition of the population, whereas for knee OA outcomes, changes in the strength of the associations with sociodemographic factors appeared more important. All outcomes were concentrated among people with lower education in all study years. The relative inequalities declined over the study period, while the absolute inequalities increased for knee OA outcomes and remained stable for hip OA. Conclusion: Our findings show an increasing burden of all studied OA outcomes. Moreover, our findings suggest persistent educational inequalities with more surgeries and specialist visits among lower-educated individuals. Future research should incorporate additional variables to better understand and address these inequalities.

Does lower educational attainment increase the risk of osteoarthritis surgery? a Swedish twin study.

BACKGROUND: Previous studies have reported an inverse association between educational attainment and different osteoarthritis (OA) outcomes. However, none of the previous studies have accounted for potential confounding by early-life environment and genetics. Thus, we aimed to examine the association between educational attainment and knee and hip OA surgery using twin data. METHODS: From the Swedish Twin Registry (STR), we identified dizygotic (DZ) and monozygotic (MZ) twins. All twins in the STR aged 35 to 64 years were followed from January the 1st 1987 or the date they turned 35 years until OA surgery, relocation outside Sweden, death or the end of 2016 (18,784 DZ and 8,657 MZ complete twin pairs). Associations between educational attainment and knee and hip OA surgery were estimated in models matched on twin pairs, using Weibull within-between (WB) shared frailty model. RESULTS: For knee OA surgery, the analysis matched on MZ twins yielded a within-estimate hazard ratio (HR) per 3 years of education, of 1.06 (95% CI: 0.81, 1.32), suggesting no association between the outcome and the individual´s education. Rather, there seemed to be a so called familial effect of education, with a between-pair estimate of HR = 0.71 (95% CI: 0.41, 1.01). For hip OA surgery, the within- and between-pair estimates for MZ twins were 0.92 (95% CI: 0.69, 1.14) and 1.15 (95% CI: 0.87, 1.42), respectively. CONCLUSIONS: Our results suggest that the inverse associations between education and knee/hip OA surgery observed in cohort studies are potentially confounded by unobserved familial factors like genetics and/or early life exposures.

Socioeconomic Inequalities in All-Cause and Cause-Specific Mortality Among Patients With Osteoarthritis in the Skåne Region of Sweden.

OBJECTIVE: To assess the association between education and all-cause and cause-specific mortality among patients with osteoarthritis (OA) in comparison to an OA-free reference cohort. METHODS: Using data from the Skåne Healthcare Register, we identified all residents age ≥45 years in the region of Skåne in southern Sweden with doctor-diagnosed OA of peripheral joints between 1998 and 2013 (n = 123,993). We created an age- and sex-matched reference cohort without OA diagnosis (n = 121,318). Subjects were followed until death, relocation outside Skåne, or the end of 2014. The relative index of inequality (RII) and the slope index of inequality (SII) were estimated by the Cox model and Aalen's additive hazard model, respectively. RESULTS: We found an inverse association between education and mortality. The magnitude of relative inequalities in all-cause mortality were comparable in the OA, with an RII of 1.53 (95% confidence interval [95% CI] 1.46, 1.61), and reference cohorts (RII 1.54 [95% CI 1.47, 1.62]). The absolute inequalities were smaller in the OA cohort (all-cause deaths per 100,000 person-years, SII 937 [95% CI 811, 1,063]) compared with the reference cohort (SII 1,265 [95% CI 1,109, 1,421]). Cardiovascular mortality contributed more to the absolute inequalities in the OA cohort than in the reference cohort (60.1% versus 48.1%) while the opposite was observed for cancer mortality (8.5% versus 22.3%). CONCLUSION: We found higher all-cause and cause-specific mortality in OA patients with lower education. The observed inequalities in the OA cohort reflect the inequalities in the population at large. The greater burden of cardiovascular diseases in OA patients suggests that proper management of cardiovascular risk factors in OA patients is important.