A cross-national comparison of income gradients in oral health quality of life in four welfare states: application of the Korpi and Palme typology

Abstract

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 chi(2) 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.

Figure 1

Ideal–typical models of social insurance institutions. Reprinted with permission from Korpi W, Palme J. The paradox of redistribution and strategies of equality: welfare state institutions, inequality, and poverty in the western countries. Am Sociol Rev 1998;63:661–87. The four-sided figures represent the social structure of society with high-income earners at the top and low-income earners at the bottom. White areas represent the non-covered population. Horizontal lines indicate flat-rate benefits. Vertical lines indicate earnings-related benefits. Ellipses in the voluntary state-subsidised model indicate separate insurance programmes. Angled lines in the corporatist model indicate insurance programmes organised separately for different occupational categories. Targeted welfare state: has a means-tested scheme of flat-rate benefits financed through taxation of the economically active. Benefits are minimal and coverage limited to low income earners. Australia was the only country that fitted this typology. Basic Security welfare state: Benefits are modest but coverage is universal. Like the Targeted state, depends on middle and high income earners seeking supplementary insurance through private providers. Countries were the UK, Canada, Denmark, Netherlands, Ireland, New Zealand, Switzerland and the United States. Corporatist welfare state: Eligibility for benefits is based on compulsory membership in specified occupational categories and benefits are earnings-related (as opposed to flat-rate). This produces a much bigger budget allowing substantially greater expenditure on benefits than do the Targeted or Basic Security regimes. The more generous provision upholds the accustomed higher standards of living of middle income earners, acting as disincentive to seek private insurance arrangements. Countries were Germany, Austria, Belgium, France, Italy and Japan. Encompassing welfare state: Earnings-related benefits for all citizens that tend to be generous. This suppresses demand for private insurance from the middle and high income earning segments of the population. Countries were Finland, Norway and Sweden. Voluntary State Subsidised welfare state: No country was fitted.

Figure 2

Household income gradients in adjusted mean Oral Health Impact Profile (OHIP-14) severity scores per person for dentate adults in Germany (2001), Finland (2000), the UK (1998) and Australia (2002). Adjustment for sex and age in years was achieved using separate linear regression models for each country.