Income-based differences in health care utilization in relation to mortality: Trends in the Swedish population between 2004-2017

Background Despite universal health care, socioeconomic differences in health care utilization (HCU) persist in modern welfare states. The aim of this study is to assess income-based differences in utilization of primary- and specialized care in relation to mortality for the Swedish general population (>15 years old) between 2004 and 2017. Methods and Findings Using a repeated cross-sectional register-based study design, data on utilization of i) primary-ii) specialized outpatient- and iii) inpatient care, as well as iv) cause of death, were linked to family income and sociodemographic control variables. HCU and mortality for all-disease as well as for the five disease groups causing most deaths were compared for the lowest (Q1) and highest (Q5) income quintile using logistic regression. We also analysed income-related differences in the number of health care encounters ≤5 years prior to death. In 2017, for all diseases combined, Q1 utilized marginally more primary- and specialized outpatient care than Q5 (adjusted odds ratio [OR] =1.07, 95% CI: 1.07, 1.08; OR 1.04, 95% CI: 1.04, 1.05, respectively), and considerably more inpatient care (OR=1.44, 95% CI: 1.43, 1.45). The largest relative inequality was observed for mortality (OR 1.78, 95% CI: 1.74, 1.82). This pattern was broadly reproduced for each of the five diseases. Time trends in HCU inequality varied by level of care. Each year, Q1 (vs. Q5) used more inpatient care and suffered increasing mortality rates. However, usage of primary- and specialized outpatient care increased more among Q5 than in Q1. Finally, Q1 and Q5 had similar number of encounters in primary- and inpatient care ≤5 years prior to death, but Q1 had significantly fewer outpatient encounters. Conclusions Income-related differences in the utilization of primary and specialized outpatient care were considerably smaller than for mortality, and this discrepancy widened with time. Facilitating motivated use of primary- and outpatient care among low-income groups could help mitigate the growing health inequalities. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Initials of the authors who received each award: E.A Grant numbers awarded to each author: DNR: 2021-00176 The full name of each funder: Swedish Research Council for Health, Working Life and Welfare URL of each funder website: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethical standards: The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. The registration number for the ethical applications and approvals by Regional Ethical Review Board, Stockholm, Sweden are: DNR 2018/1339-31/5, 2018/2292-32, 2019-02185, 2021-00657 and 2022-03111-02. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data cannot be shared publicly because of personal integrity. Data are available from the Swedish National Board of Health and Wellfare and Statistics Sweden, for researchers who meet the criteria for access to confidential data. * HCU : Health care utilization SES : Socioeconomic status Q1 : Lowest income quintile Q5 : Highest income quintile