Ian Diamond

Birth interval and family effects on postneonatal mortality in Brazil

In this paper random-effects logistic models are used to analyze the effects of the preceding birth interval on postneonatal mortality in Brazil, controlling for the correlation of survival outcomes between siblings. The results are compared to those obtained by using ordinary logistic regression. Family effects are found to be highly significant in the random-effects model, but the substantive conclusions of the ordinary logistic model are preserved. In particular, birth interval effects remain highly significant.

A multilevel analysis of the effects of rurality and social deprivation on premature limiting long term illness

STUDY OBJECTIVE To examine the geographical variation in self perceived morbidity in the south west of England, and assess the associations with rurality and social deprivation. DESIGN A geographically based cross sectional study using 1991 census data on premature Limiting Long Term Illness (LLTI). The urban-rural and intra-rural variation in standardised premature LLTI ratios is described, and correlation and regression analyses explore how well this is explained by generic deprivation indices. Multilevel Poisson modelling investigates whether Customised Deprivation Profiles (CDPs) and area characteristics improve upon the generic indices. SETTING Nine counties in the south west of England PARTICIPANTS The population of the south west enumerated in the 1991 census. MAIN RESULTS Intra-rural variation is apparent, with higher rates of premature LLTI in remoter areas. Together with high rates in urban areas and lower rates in the semi-rural areas this indicates the existence of a U shaped relation with rurality. The generic deprivation indices have strong positive relations with premature LLTI in urban areas, but these are a lot weaker in semi-rural and rural locations. CDPs improve upon the generic indices, especially in the rural settings. A substantial reduction in unexplained variation in rural areas is seen after controlling for the level of local isolation, with higher isolation, at the wider geographical scale, being related to higher levels of LLTI. CONCLUSIONS This study highlights the need to treat rural areas as heterogeneous, although this has not been the tendency in health research. Generic deprivation indices are unlikely to be a true reflection of levels of deprivation in rural environments. The importance of CDPs that are specific to the area type and health outcome is emphasised. The significance of physical isolation suggests that accessibility to public and health services may be an important issue, and requires further research.

Determinants of infant mortality in Malawi: an analysis to control for death clustering within families

The 1988 Malawi Traditional and Modern Methods of Child Spacing Survey data are used to identify determinants of infant mortality in Malawi. The logistic binomial analysis shows that socioeconomic factors are significant even during the neonatal period while the length of the preceding birth interval is significant in the post-neonatal period only. There is a strong familial correlation of mortality risks during both the neonatal and post-neonatal periods but the effect of geographical area of residence is stronger in the post-neonatal period.

The (mis)Representation of Rural Deprivation

The authors consider the definition and measurement of deprivation and of rurality in the context of health-care research. Parallels are drawn between the methodological issues involved in the measurement of deprivation and of rurality. An empirical study of the South West of England reveals the extent of disagreement between standard rurality measures; in particular, the authors suggest that rural deprivation will be poorly represented by the conventional approaches. They argue for the development of new approaches to the measurement of deprivation in rural areas, in which advantage is taken of contemporary data sources.

What Determines Geographical Variation in Rates of Acceptance onto Renal Replacement Therapy in England

Objective: To determine the independent effects of need and supply factors on the known geographical variation in acceptance rates onto renal replacement therapy (RRT) in England. Methods: Data were obtained from all renal units in England on the characteristics of all cases aged 16 years and over, resident in England, who were accepted onto RRT in 1991 and 1992. Of these, 5715 (94.5%) had a valid postcode that could be matched to a census ward. Multilevel modelling using Poisson regression was used. The number of acceptances in each census ward within age bands 16–34, 35–64 and 65+ was the dependent variable. Independent effects modelled were: (1) individual factors (age, sex); (2) census ward need factors — ethnicity (expressed as the percentage of the ward population that was Asian or African-Caribbean), socio-economic deprivation — and supply factors — ‘access’ to the nearest renal unit using crowfly and road travel time and distance, and services available to each ward expressed as number of haemodialysis stations per 100 000 catchment population of the nearest renal unit; (3) district health authority level effects. Results: Age was a major determinant of acceptance, with a 7-fold higher rate in males aged over 64 years compared with younger men. Acceptance rates were lower in females, with a negative age-sex interaction in females aged over 64 years. The percentage of both Asian and African-Caribbean populations per ward was a highly significant positive determinant. Deprivation was also a significant determinant, best represented by a customised index. There was an inverse relation of acceptance with distance, especially road travel time. Other supply side variables had a significant effect though there was no independent district effect. There was some variation in the strength of these relationships by type of area (Greater London, urban and non-urban). Conclusions: Need and supply factors influence service use as expressed as acceptance onto RRT. Pressure to expand RRT services needs to be aimed at areas with large minority ethnic populations and those living far from existing units.

Spatial variation in teenage conceptions in south and west England

Multilevel Poisson models are used to identify factors influencing variation in census ward level teenage conception rates. Multilevel logistic models are also employed to examine the outcome of these conceptions. Demographic and socioeconomic characteristics are accounted for as well as access to family planning services. The paper emphasizes the importance of customized deprivation indices that are specific to the health outcome in urban and rural areas.

Child immunisation in Ghana: the effects of family, location and social disparity

The data from the Demographic and Health Survey conducted in Ghana in 1988 are used to identify determinants of immunisation uptake for children under 5 years. The logistic binomial analysis shows that socioeconomic factors are significant, especially womens education and region, and that the type of prenatal care received by the mother is also important. There is a strong familial correlation of vaccination behaviours, and there is also clustering of data within enumeration areas.

Interrelations between three proxies of health care need at the small area level: an urban/rural comparison

Study objective: To examine the relations between geographical variations in mortality, morbidity, and deprivation at the small area level in the south west of England and to assess whether these relations vary between urban and rural areas. Design: A geographically based cross sectional study using 1991 census data on premature limiting long term illness (LLTI) and socioeconomic characteristics, and 1991–1996 data on all cause premature mortality. The interrelations between the three widely used proxies of health care need are examined using correlation coefficients and scatterplots. The distribution of standardised LLTI residuals from a regression analysis on mortality are mapped and compared with the distribution of urban and rural areas. Multilevel Poisson modelling investigates whether customised deprivation profiles improve upon a generic deprivation index in explaining the spatial variation in morbidity and mortality after controlling for age and sex. These relations are examined separately for urban, fringe, and rural areas. Setting: Nine counties in the south west of England. Participants: Those aged between 0–64 who reported having a LLTI in the 1991 census, and those who died during 1991–1996 aged 0–74. Main results: Relations between both health outcomes and generic deprivation indices are stronger in urban than rural areas. The replacement of generic with customised indices is an improvement in all area types, especially for LLTI in rural areas. The relation between mortality and morbidity is stronger in urban than rural areas, with levels of LLTI appearing to be greater in rural areas than would be predicted from mortality rates. Despite the weak direct relations between mortality and morbidity, there are strong relations between the customised deprivation indices computed to predict these outcomes in all area types. Conclusions: The improvement of the customised deprivation indices over the generic indices, and the similarity between the mortality and morbidity customised indices within area types highlights the importance of modelling urban and rural areas separately. Stronger relations between mortality and morbidity have been revealed at the local authority level in previous research providing empirical evidence that the inadequacy of mortality as a proxy for morbidity becomes more marked at lower levels of aggregation, especially in rural areas. Higher levels of LLTI than expected in rural areas may reflect different perceptions or differing patterns of illness. The stronger relations between the three proxies in urban than rural areas suggests that the choice of indicator will have less impact in urban than rural areas and strengthens the argument to develop better measures of health care need in rural areas.

The Incidence of Drug and Solvent Misuse among Southern English Normal Comprehensive Schoolchildren

Two surveys were carried out in 1985 and 1986 among fourth and fifth year comprehensive schoolchildren to estimate the incidence of drug and solvent misuse. Around one-fifth of the children had used drugs at some time and over half of these had used drugs recently. There was a clear relationship between drug and solvent misuse and adverse social characteristics. Drug misuse was seen as a serious problem by almost all the respondents.