Background: The extent to which welfare states may influence health outcomes has not been explored. It was hypothesised that policies which target the poor are associated with greater income inequality in oral health quality of life than those that provide earnings-related benefits to all citizens.
Methods: Data were from nationally representative surveys in the UK (n = 4064), Finland (n = 5078), Germany (n = 1454) and Australia (n = 2292) conducted from 1998 to 2002. The typology of Korpi and Palme classifies these countries into four different welfare states. In each survey, subjects completed the Oral Health Impact Profile (OHIP-14) questionnaire, which evaluates the adverse consequence of dental conditions on quality of life. For each country, survey estimation commands were used to create linear regression models that estimated the slope of the gradient between four quartiles of income and OHIP-14 severity scores. Parameter estimates for income gradients were contrasted across countries using Wald χ2 tests specifying a critical p value of 0.008, equivalent to a Bonferroni correction of p<0.05 for the six pairwise tests.
Results: Statistically significant income gradients in OHIP-14 severity scores were found in all countries except Germany. A global test confirmed significant cross-national differences in the magnitude of income gradients. In Australia, where a flat rate of benefits targeted the poor, the mean OHIP-14 severity score reduced by 1.7 units (95% CI −2.15 to −1.34) with each increasing quartile of household income, a significantly steeper gradient than in other countries.
Conclusion: The coverage and generosity of welfare state benefits appear to influence levels of inequality in population oral health quality of life.
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Competing interests: None.
Funding: This study was supported by NIH/NIDCR R21-DE018980. The Health 2000 Health Examination Survey in Finland was organised by the National Public Health Institute (KTL) of Finland (http://www.ktl.fi/health2000), and partly supported by the Finnish Dental Society Apollonia and the Finnish Dental Association. The National Dental Telephone Interview Survey 2002 was supported by the Australian Government Department of Health and Ageing, Population Health Division. AES is an Australian National Health and Medical Research Council Sidney Sax (Public Health) Fellow.
Ethics approval: Institutional Review Board consisting of members of the German Dental Association, Association of German Chambers of Dentists and Federal Association of Statutory Health Insurance Dentists.