Matthew Sutton

Income, Income Inequality and Health: What can we Learn from Aggregate Data?

It has been suggested that, especially in countries with high per capita income, there is an independent effect of income distribution on the health of individuals. One source of evidence in support of this relative income hypothesis are analyses of aggregate cross section data on population health, per capita income and income inequality. We examine the empirical robustness of cross-section analyses by using a new data set to replicate and extend the approach in a frequently cited paper. We find that the estimated relationship between income inequality and life expectancy is dependent on the data set used, the functional form estimated and the way in which the epidemiological transition is specifed. The association is never significant in any of our models. We argue there are serious methodological difficulties in using aggregate cross sections as means of testing hypotheses about the effect of income, and its distribution, on the health of individuals.

Inequality in the geographical distribution of general practitioners in England and Wales 1974-1995

Objectives: To compare geographical inequality in the distribution of general practitioners (GPs), other resources and mortality around 1995 in England and Wales; to measure trends between 1974 and 1995 in inequality of GP distribution; to examine the implications of different need adjustments and inequality measures on the degree of geographic inequality; and to analyse the impact of policies (increased supply, area inducements and entry regulation) on inequality. Methods: Measurement of relative inequality (decile ratio, Gini coefficient, Atkinson index) and absolute inequality (standard deviation) in the ratio of GPs to need-adjusted population in former Family Practitioner Committee/Family Health Services Authority areas each year from 1974 to 1995; and relative inequality across areas in the distributions of income, other resources and standardised mortality ratios (SMRs) around 1995. Regression of 1995 GP/population ratios on 1974 ratios. Application of equalising net advantages location model to GP distribution. Results: Inequality in the distribution of GPs in 1995 was less than inequality in other primary care resources, but greater than inequalities in disposable income, SMRs, primary school expenditure, and hospital and community health services expenditure. The decile ratio shows little change between 1974 and 1995. Gini and Atkinson inequality indices indicate some reduction in inequality between 1974 and 1980, but little change thereafter. The standard deviation of need-adjusted provision increased over the period. Areas that had the lowest GP provision in 1974 tended to have the lowest in 1995. Conclusions: The choice between relative and absolute inequality measures and, to a lesser extent, the method of adjusting for need affect conclusions about the trend in inequality. Both types of measure and most need adjustments suggest that the policies adopted did not lead to a reduction in inequality over the period. Interactions between policies may reduce their overall effectiveness.

Mapping visual analogue scale health state valuations onto standard gamble and time trade-off values

Despite becoming increasingly common in evaluations of health care, different methods of quantitatively measuring health status appear to produce different valuations for identical descriptions of health. This paper reports on a study that elicited health state valuations from the general public using three different methods: the visual analogue scale (VAS), the standard gamble (SG) and the time trade-off (TTO). Two variants of the SG and TTO were tested: Props (using specially designed boards and cards); and No Props (using a self-completion booklet). This paper focuses on empirical relationships between health state valuations from the VAS and the (four) other methods. The relationships were estimated using Tobit regression of individual-level data. In contrast to a priori expectations, the mapping functions estimated suggest that differences are more pronounced across variant than across method. Furthermore, relationships with VAS scores are found to depend on the severity of the state: TTO Props valuations are higher than VAS responses for mild states and lower for more severe states; SG Props valuations are broadly similar to VAS scores over a wide range; and No Props responses are consistently higher than VAS valuations, particularly for more severe states. Explanations are proposed for these findings.

Income, relative income, and self-reported health in Britain 1979-2000

We test the relative income hypothesis that an individuals health depends on the distribution of income in a reference group, as well as on the income of the individual. We use data on 231 208 individuals in Great Britain from 19 rounds of the General Household Survey between 1979 and 2000. Results are insensitive to the measure of self-assessed health used but the sign and significance of the effect of relative income depend on the reference group (national or regional) and the measure of relative income (Gini coefficient, absolute or proportional difference from the reference group mean, Yitzhaki absolute and proportional relative deprivation and affluence). Only one model (relative deprivation measured as income proportional to regional mean income) performs better than the model without relative income and has a positive estimated effect of absolute income on health. In this model the increase in the probability of good health from a ceteris paribus reduction in relative deprivation from the upper quartile to zero is 0.010, whereas an increase in income from the lower to the upper quartile increases the probability by 0.056. While our results provide only very weak support for the relative deprivation hypothesis, the inevitable correlation of measures of individual income and relative deprivation measured by comparing income and incomes in a reference group makes identification of the separate effects of income and relative deprivation problematic.

The demand for elective surgery in a public system: time and money prices in the UK National Health Service

We construct a model of the admission process for patients from general practices for elective surgery in the UK National Health Service. Public patients face a positive waiting time, but a zero money price. Fundholding practices faced a positive money price for each patient admitted. The model is tested with data on general practice admission rates for cataract procedures in an English Health Authority. Admission rates are negatively related to waiting times and distance to hospital. Practices respond to financial incentives as predicted by the model: fundholding practices have lower admission rates than non-fundholders and respond differently to changes in waiting times and patient characteristics.

Do measures of self-reported morbidity bias the estimation of the determinants of health care utilisation?

Most national surveys of health care utilisation capture only self-reported measures of morbidity. If self-reported morbidity is measured with error, then the results of applied work may be misleading. In this paper we propose a model of the relationship between morbidity and health service utilisation which allows for reporting errors and simultaneity. Errors in self-reported morbidity are expressed as a function of person-specific reporting thresholds and recent contact with health services, arising because of better self-evaluation of current health status or a desire to justify consumption of a publicly-provided good. We demonstrate the bias in ignoring the potential problems of reporting errors and simultaneity for a variety of special cases, but in the general case the biases are of ambiguous sign. The empirical nature of these biases is investigated using limiting long-standing illness (LLI) and recent contact with a General Practitioner (GP) in two waves of The UK Health and Lifestyle Survey. Biomedical measures of functioning are used as objective indicators of health status. We find evidence of substantial and significant differences between individuals in reporting thresholds and some evidence that the reporting of LLI may depend on recent visits to a GP. Adjustments for these biases significantly increase the estimated effect of morbidity on utilisation.

The influence of households on drinking behaviour: a multilevel analysis.

This paper examines the influence of household membership and area of residence on individual drinking behaviour using a multilevel modelling approach. The effects are investigated using data from the Health Survey for England (HSE) in which multiple interviews were conducted in the same household. With the use of postal address, the data were organised into a hierarchical structure of individuals within households within enumeration districts. After controlling for characteristics of individuals thought to influence or correlate with drinking behaviour, unexplained variation in alcohol consumption was attributed to individual, household and area effects. Household influences on drinking behaviour far outweigh the influences of place of residence. Policies aimed at reducing alcohol consumption, particularly by heavy drinkers, may be best targeted at the household level.

Differences in the quality of primary medical care for CVD and diabetes across the NHS: evidence from the quality and outcomes framework

BackgroundHealth policy in the UK has rapidly diverged since devolution in 1999. However, there is relatively little comparative data available to examine the impact of this natural experiment in the four UK countries. The Quality and Outcomes Framework of the 2004 General Medical Services Contract provides a new and potentially rich source of comparable clinical quality data through which we compare quality of primary medical care for coronary heart disease (CHD), stroke, hypertension and diabetes across the four UK countries.MethodsA cross-sectional analysis was undertaken involving 10,064 general practices in England, Scotland, Wales and Northern Ireland. The main outcome measures were prevalence rates for CHD, stroke, hypertension and diabetes. Achievement on 14 simple process, 3 complex process, 9 intermediate outcome and 5 treatment indicators for the four clinical areas.ResultsPrevalence varies by up to 28% between the four UK countries, which is not reflected in resource distribution between countries, and penalises practices in the high prevalence countries (Wales and Scotland). Differences in simple process measures across countries are small. Larger differences are found for complex process, intermediate outcome and treatment measures, most notably for Wales, which has consistently lower quality of care. Scotland has generally higher quality than England and Northern Ireland is most consistently the highest quality.ConclusionPreviously identified weaknesses in Wales related to waiting times appear to reflect a more general quality problem within NHS Wales. Identifying explanations for the observed differences is limited by the lack of comparable data on practice resources and organisation. Maximising the value of cross-jurisdictional comparisons of the ongoing natural experiment of health policy divergence within the UK requires more detailed examination of resource and organisational differences.

Health and income inequality: attempting to avoid the aggregation problem

Attempts to test the relative deprivation hypothesis, that income inequality affects individual health, are subject to the aggregation problem. Waldmann (Quarterly Journal of Economics 107, 1992) ingeniously attempts to overcome the difficulty by using income data for the poor and the share of income accruing to the rich. The study finds that his results do not hold for a more recent data set and it suggests that his method may not overcome the aggregation problem.

Ethnic Differences in Substance Use and Alcohol-Use-Related Mortality among First Generation Migrants to England and Wales

Epidemiological studies among migrant ethnic groups are potentially important as a way to provide insight into the relative importance of genetic, cultural, and socioeconomic factors in the etiology of substance use disorders. This paper summarizes prior United Kingdom studies of the prevalence of substance-use-associated problems in different ethnic groups before analyzing trends in recent mortality data by country of birth. On this evidence, rates of alcohol-related mortality may be marginally higher for those born in the Caribbean than for the native British, but are substantially raised for those born in Ireland and the Indian subcontinent. There is some indication that rates for the Caribbean and possibly the Irish groups have risen more rapidly than for the national population over a 12-year period. These differences in mortality rates seem to have arisen for complex reasons.