Graham Bentham

Epidemiology of systemic vasculitis: a ten-year study in the United Kingdom.

OBJECTIVE To describe the epidemiology of the primary systemic vasculitides (PSV; Wegeners granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, polyarteritis nodosa) in a well-defined population over a 10-year period. METHODS An inception cohort of patients from the Norwich Health Authority (NHA) who were >15 years of age and had PSV first diagnosed between January 1, 1988 and December 31, 1997 was collected. Incidence rates were adjusted for age and sex to the 1992 population. The prevalence of PSV in this cohort was estimated on December 31, 1997. Patients were classified according to the American College of Rheumatology 1990 vasculitis criteria and the Chapel Hill Consensus definitions. RESULTS Eighty-two NHA residents fulfilled the inclusion criteria. There were 47 men and 35 women, with a mean age of 62.9 years (median 65.0 years). The overall annual incidence of PSV among NHA residents was 19.8/million (95% confidence interval [95% CI] 15.8-24.6). The point prevalence on December 31, 1997 was 144.5/million (95% CI 110.4-185.3). PSV was more common in males (23.5/million; 95% CI 17.3-31.3) than females (16.4/million; 95% CI 11.4-22.8). The age- and sex-specific incidence showed a clear increase with age, with an overall peak in the 65-74 year age group (60.1/million). CONCLUSION In our study population, the annual incidence of PSV is slowly increasing with time and the incidence is greatest in the elderly.

Migration and morbidity: Implications for geographical studies of disease

Many studies have examined associations between the geographical patterns of disease and possible causal factors. Underlying such studies is the assumption that residence in an area can be equated with exposure to conditions that pertain there. Migration upsets this assumption. Using data on self-reported morbidity from the 1981 Census for Great Britain it is shown that the health status of migrants differs considerably from that of non-migrants. Young migrants, particularly those moving longer distances are relatively healthy. Area of net out-migration of this age group are therefore likely to become characterised by a less healthy population whereas the reverse will be true of areas of net in-migration. Amongst older people migration tends to be selective of those in poor health moving shorter distances to avoid environmental health hazards or to be closer to medical care. This has the curious effect of increasing morbidity and mortality rates in areas with favourable environmental conditions and good medical services. Migration is therefore likely to be a significant source of error in geographically based studies of the association between disease and the environment. Sometimes the effect will be to obscure real environmental causes of disease. In other circumstances spurious association will be produced. These problems will be greatest for diseases with long latent periods which allow plenty of time for mobility of the population. Problems are also likely to increase with the growing mobility of the population.

Geoepidemiology of systemic vasculitis: comparison of the incidence in two regions of Europe

OBJECTIVE The aetiopathogenesis of the primary systemic vasculitides (PSV) is unknown but includes both environmental and genetic factors. The development of classification criteria/definitions for PSV allows comparison of the epidemiology between different regions. METHODS The same methods and the American College of Rheumatology (1990) criteria or Chapel Hill definitions were used to compare the epidemiology of Wegeners granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, and polyarteritis nodosa in Norwich (east England population 413 500) and Lugo (northwest Spain population 204 100). Patients with PSV were identified between 1 January 1988 and 31 December 1998. RESULTS Overall, the incidence of PSV in adults was almost equal in Norwich (18.9/million) and Spain (18.3/million). The incidence of Wegeners granulomatosis in Norwich (10.6/million) was greater than in Spain (4.9/million). There was a marked age-specific increase in incidence in Norwich with a peak age 65–74 years (52.9/million), but a virtually equal age distribution between ages 45 and 74 in Lugo (34.1/million). There was no significant increase with time in either population, or evidence of cyclical changes in incidence. CONCLUSION These data support the suggestion that environmental factors may be important in the pathogenesis of PSV.

Epidemiology of vasculitis in Europe

We recently compared the annual incidence of primary systemic vasculitis (PSV) in two different regions of Europe (Norwich, UK (latitude 52°N) and Lugo, Spain (latitude 43°N)).1Wegeners granulomatosis (WG) was more common in Norwich (10.6/million) than in Spain (4.9/million), though the overall incidence of PSV was similar. This supports the idea that environmental factors may be important in the aetiopathogenesis of PSV. To extend our observations we have now studied the incidence of PSV in northern Europe (Tromso, Norway (latitude 70°N)). …

The potential effects of climate change on winter mortality in England and Wales

In Britain death rates from several important causes, particularly circulatory and respiratory diseases, rise markedly during the colder winter months. This close association between temperature and mortality suggests that climate change as a result of global warming may lead to a future reduction in excess winter deaths. This paper gives a brief introductory review of the literature on the links between cold conditions and health, and statistical models are subsequently developed of the associations between temperature and monthly mortality rates for the years 1968 to 1988 for England and Wales. Other factors, particularly the occurrence of influenza epidemics, are also taken into account. Highly significant negative associations were found between temperature and death rates from all causes and from chronic bronchitis, pneumonia, ischaemic heart disease and cerebrovascular disease. The statistical models developed from this analysis were used to compare death rates for current conditions with those that might be expected to occur in a future warmer climate. The results indicate that the higher temperatures predicted for 2050 might result in nearly 9000 fewer winter deaths each year with the largest contribution being from mortality from ischaemic heart disease. However, these preliminary estimates might change when further research is able to make into account a number of additional factors affecting the relationship between mortality and climate.

Regional variations in mortality rates in England and Wales: An analysis using multi-level modelling

Mortality rates in England and Wales display a persistent regional pattern indicating generally poorer health in the North and West. Some of this is simply a reflection of regional differences in the extent of social deprivation which is known to exert a profound influence on health. Part of the pattern may also be the result of regional differences in urbanization which also affect mortality rates. However, there may be important regional differences over and above these compositional effects. This study attempts to establish the magnitude of such independent regional differences in mortality rates by using the techniques of multi-level modelling. Standardized mortality rates (SMRs) for males and females under 65 for 1989-91 in local authority districts are grouped into categories using the ACORN classification scheme. The Townsend Index is included as a measure of social deprivation. Using a cross-classified multi-level model, it is shown that region accounts for approximately four times more variation in SMRs than is explained by the ACORN classification. Analysis of diagnostic residuals show a clear North-South divide in excess mortality when both regional and socio-economic classification of districts are modelled simultaneously, a possibility allowed for by the use of a multi-level model.

Tuberculosis mortality in England and Wales during 1982-1992: its association with poverty, ethnicity and AIDS

This paper seeks to establish the strength of association between contemporary tuberculosis (TB) in England and Wales and several potential aetiological factors. It presents an ecological analysis of standardised annual TB mortality rates for the 403 local authority districts between 1982 and 1992, disaggregated by age and sex. Social, demographic and ethnicity measures from the 1981 and 1991 censuses and standardised annual AIDS-related mortality rates for young men are used to calculate Poisson regression models. A strong association was found between all TB mortality groups and overcrowding at the household level. For women, no other measures improved the explanatory power of the models. In multiple regressions, both poverty and AIDS-related mortality explained additional variation in the model for younger men. The link between ethnicity and tuberculosis notifications was not reflected in this analysis of mortality. For all groups no evidence of a positive relationship with ethnicity was found, once overcrowding had been accounted for. The significance of household as opposed to district level crowding suggests that prolonged contact is required for disease transmission. Regression analysis indicates that it is the overcrowding and poverty among ethnic populations that is significant for their tuberculosis mortality. The fact that the relationship between AIDS and TB is confined to the group most typical of AIDS patients provides evidence that AIDS has little influence on the level of tuberculosis mortality in the wider population. Explanations for the observed relationship include preferential certification, migration for treatment and shortcomings in health care provision.

Climate change and the incidence of food poisoning in England and Wales

In recent years there have been several spells of high temperatures providing analogues for the conditions that might become more common as a result of the enhanced greenhouse effect. Statistical models were developed of the relationship between the monthly incidence of food poisoning and temperatures and these were then used to provide estimates of the possible effects of future warmer summers. Routinely collected data on the number of reported cases of food poisoning were analysed for the years 1982–1991. Regression analysis was used to establish the relationship between the monthly incidence of food poisoning and temperatures of the same and the previous month. Published scenarios for future temperatures were applied to these statistical models to provide estimates of the possible impacts of warmer conditions. The monthly incidence of food poisoning was found to be significantly associated with the temperature of the same and of the previous month with the latter having the stronger effect. Using published data on the relationship between reported and actual numbers of cases of food poisoning, it is estimated that annually there might be an additional 179 000 cases of food poisoning by the year 2050 as a result of climate change. The observed relationship with the same months temperature underlines the need for improvements in storage, preparation and hygiene close to the point of consumption. However, there was a much stronger relationship with the temperature of the previous month, indicating the importance of conditions earlier in the food production process. Improvements in areas such as animal husbandry and slaughtering may also be necessary to avoid the adverse effects of a warmer climate.

A re-evaluation of the impact of temperature and climate change on foodborne illness

The effects of temperature on reported cases of a number of foodborne illnesses in England and Wales were investigated. We also explored whether the impact of temperature had changed over time. Food poisoning, campylobacteriosis, salmonellosis, Salmonella Typhimurium infections and Salmonella Enteritidis infections were positively associated (P<0.01) with temperature in the current and previous week. Only food poisoning, salmonellosis and S. Typhimurium infections were associated with temperature 2-5 weeks previously (P<0.01). There were significant reductions also in the impact of temperature on foodborne illnesses over time. This applies to temperature in the current and previous week for all illness types (P<0.01) except S. Enteritidis infection (P=0.079). Temperature 2-5 weeks previously diminished in importance for food poisoning and S. Typhimurium infection (P<0.001). The results are consistent with reduced pathogen concentrations in food and improved food hygiene over time. These adaptations to temperature imply that current estimates of how climate change may alter foodborne illness burden are overly pessimistic.

Emergency medical service accessibility and outcome from road traffic accidents

Road traffic accidents cause several thousand deaths each year in England and Wales. One approach to reducing this toll is to ensure that services are planned to achieve early response of ambulances to accident victims and their rapid conveyance to a hospital with good accident and emergency facilities. In order to undertake medical care of the highest quality, there has been a policy of concentrating such facilities in large units. Unfortunately, this has the disadvantage that distances and travel times from some accident sites to these centres can be considerable, particularly in rural areas. The county of Norfolk is a generally rural area which has a high death rate from road traffic accidents, and it has been suggested that access to accident and emergency facilities may be a factor. Data on serious and fatal road accidents from police accident records were analysed for the period 1987 to 1991. The time taken for an ambulance to reach each accident and to convey the victim to the nearest hospital accident and emergency department was estimated using a geographical information system. Regression analysis was used to analyse the factors affecting the odds of death versus serious injury for each individual. An elevated probability of death was found among the old, pedestrians, casualties involved in multiple accidents, and casualties on roads with higher speed limits. However, no relationship was found between outcome and the estimated time taken to reach victims and to convey them to hospital, either before or after adjustment for other factors.(ABSTRACT TRUNCATED AT 250 WORDS)