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RESEARCH AND PRACTICE |
At the time of the study, Kate A. Levin and Alastair H. Leyland were with the Medical Research Councils Social and Public Health Sciences Unit, University of Glasgow, Scotland.
Correspondence: Requests for reprints should be sent to Kate A. Levin, Dental Health Services Research Unit, The Mackenzie Building, Kirsty Semple Way, Dundee DD2 4BF (e-mail: klevin{at}chs.dundee.ac.uk).
| ABSTRACT |
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Objectives. We sought to describe the pattern and magnitude of urbanrural variation in ischemic heart disease (IHD) in Scotland and to examine the associations among IHD health indicators, level of rurality, and degree of socioeconomic deprivation.
Methods. We used routine population and health data on the population aged 4074 years between 1981 and 1999 and living in 826 small areas (average population=5600) in Scotland. Three IHD health indicatorsmortality rates (deaths per 100000 population), rates of continuous hospital stays (discharges per 100000 population), and rates of mortality in the hospital or within 28 days of discharge (MH+) were analyzed with multilevel Poisson models. A 4-level rurality classification was used: urban areas, remote small towns, accessible rural areas, and remote rural areas.
Results. Rates of mortality, continuous hospital stays, and MH+ increased with area socioeconomic deprivation. After adjustment for population age, gender, and deprivation, the relative risk of IHD mortality in remote rural areas was similar to that of urban areas in 1981; the relative risk of a continuous hospital stay was significantly lower (relative risk [RR] = 0.70; 95% confidence interval [CI] = 0.64, 0.76) and the relative risk of MH+ was higher (RR=1.18; 95% CI=1.04, 1.35) in remote rural areas. Mortality and MH+ declined for all ruralities over time. However, MH+ remains highest in remote rural areas and remote towns.
Conclusions. Low standardized ratios of IHD continuous hospital stays and mortality in remote rural areas mask health problems among rural populations. Although absolute and relative differences between urban and rural rates of MH+ have diminished, the relative risk of MH+ remains high in remote rural areas.
| INTRODUCTION |
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Mortality is used as a health indicator but is not necessarily a proxy for morbidity. Hospital admissions or physician consultations may also serve as indicators, but low rates of admissions or consultations may reflect poor provision or use of services but may be misinterpreted as reflecting good health. Particularly in rural areas, there is an inverse relation between distance from services and use of services, but "what is not clear from studies is the degree to which decreased use of primary care with increasing distance represents unmet need."10(p18) Because of cultural differences in interpretation of the term limiting long-term illness, self-reported health as a health indicator has also been criticized as a tool for the study of urbanrural health inequalities.11
The benefits of including a range of health measures to examine urbanrural inequalities have been discussed elsewhere.12,13 The choice of indicator is particularly important for rural small-area studies.14 Norris15 suggested lives saved per 1000 patients treated as an indicator of hospital and ambulance service performance for acute myocardial infarction that is sensitive to patient delay in seeking treatment, ambulance service performance, and hospital performance. Mortality in the hospital or within 28 days of discharge (MH+) is also affected by all of these factors and has been proposed as a reasonable indicator of IHD case fatalities16 and a recommended measure for monitoring heart disease.
We examined the pattern and magnitude of urbanrural variation in IHD in Scotland using 3 health indicatorsmortality, hospital admission, and MH+and analyzed the associations of these indicators during the period 19811999. These indicators were used to compare areas of varying degrees of rurality on the incidence and successful treatment of IHD, thus creating profiles of IHD for areas belonging to different rurality categories.
| METHODS |
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The data used in this analysis were IHD mortality data from the General Register Office for Scotland and hospital discharge data collected and linked to mortality data by the Information and Statistics Division of the National Health Service in Scotland. An episode of IHD was defined as 1 continuous hospital stay for which the diagnosis at discharge included International Classification of Diseases, Ninth Revision, codes 410414.17 These IHD episodes were collated for each postcode sector into 7 five-year age groups of men and women aged 4074 years. Men and women younger than 40 years were excluded because of the small number of IHD episodes experienced in this age group. Number of continuous hospital stays and number of patientsor 1-year admissionswere analyzed; some patients were possibly counted more than once when measuring continuous hospital stays. Length of stay was calculated by subtracting the date of admission (from the first record in a continuous stay) from the date of discharge (from the last record in the continuous stay). Average length of continuous hospital stay for each agegender group within a postcode sector was truncated to a maximum of 60 days.16 MH+ was defined as death from any cause in the hospital or within 28 days of discharge after the last episode of any stay that involved at least 1 principal diagnosis of IHD. Emergency admissions were usually observed in Accident and Emergency departments and would not normally be recorded unless the patients were transferred into another specialty department. Therefore, emergencies in which people died en route to the hospital or in the emergency room were included only in the mortality analysis.
We used the 1991 Carstairs area deprivation indicator,18 a continuous variable assigned at the postcode sector level, to categorize levels of socioeconomic deprivation. The Carstairs indicator was derived from 4 variableslack of car ownership, low social class, male unemployment, and overcrowdingand the 1991 Carstairs score ranged from 7.54 (most affluent) to 12.87 (most deprived).
Postcode sectors were classified into 4 categories by rurality: urban areas (
10000 population), remote small towns (300010000 population, > 30-minute drive from a settlement of
10000 population), accessible rural areas (< 3000 population,
30-minute drive from a settlement of
10000 population), and remote rural areas (< 3000 population, > 30-minute drive from a settlement of
10000 population). This classification was derived from that used in the Scottish Household Survey19 and has previously been used to show urbanrural differences in suicides in Scotland.9 The rurality of a postcode sector was assumed to be constant during 19811999.
We used aggregated 19811999 data to calculate crude rates and standardized ratios across rurality categories for mortality, hospital admissions, and MH+; the standard population was the 1991 population of Scotland (excluding Grampian) aged 4074 years.
A multilevel Poisson regression analysis20 was conducted using MLwiN,21 with adjustment for age, gender, and deprivation, to study the associations among deprivation, rurality, and IHD during 19811999. The models had 4 levels: health boards (14), local government districts (51), postcode sectors (826), and age and gender groups (14). (The age and gender groups formed a pseudolevel that enabled the estimation of separate mortality rates and different variances within each group.)
One-year rates of admission (number of patients admitted at least once in a 1-year period per 100 000 population) and rates of continuous hospital stays (number of hospital discharges separated by more than 28 days from a later admission per 100 000 population) are similar measures. However, stays in rural areas may be longer than in urban areas owing to greater distances between homes and health care services. Shorter distances would result in higher readmission rates in urban areas and therefore the same 1-year rates of admission as in rural areas but higher rates of continuous hospital stays. One-year rates of admission might provide a better indicator of disease incidence, but rates of continuous stays measure hospital use. Therefore, both were analyzedas a health indicator and as a measure of the population at risk when MH+ is investigatedalthough we present only rates of MH+ per continuous hospital stays.
| RESULTS |
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Standardized mortality ratios fell with increasing rurality, with the lowest ratios in remote rural areas. Hospital discharges also fell sharply with increasing rurality. Indirectly standardized ratios of continuous hospital stays and 1-year ratios of admission were lower in remote rural areas than in urban areas. These findings suggest a relatively healthy population in remote rural Scotland. However, ratios of MH+ were high in these areas.
Figure 1a
shows that mortality was consistently highest in urban areas and that mortality decreased from 1981 to 1999 for all categories of rurality, with the smallest relative decreases occurring in urban areas (Table 1
). Rates of continuous stay remained highest in urban areas and lowest in remote rural areas and increased for all rurality categories (Figure 1b
). The increase in rates of continuous hospital stay (and 1-year rates of admission) was greatest in remote rural areas. Rates of MH+ decreased for all rurality categories (Figure 1c
). Decreases in rates of MH+ per stay were greatest in remote rural areas, although small numbers in these areas suggest a less clear trend. The decrease in lengths of stay was consistent across all rurality categories except for a smaller decrease in remote small towns (Figure 1d
). However, stays in the hospital were longest in remote rural areas for almost all of the period observed.
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| DISCUSSION |
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Although rates of mortality and of continuous hospital stay are relatively low in remote rural areas, the relative risk of MH+ is greater in such areas than in urban Scotland. Even when the more conservative measure of 1-year admissions is used as the denominator for MH+ rates, rates of MH+ for remote rural areas remain higher than for urban areas. Increases in rates of stay (Table 1
) were greater than the increases in 1-year rates of admission. These changes, along with decreasing lengths of stay, suggest that a pattern of a small number of relatively long stays per admission has been replaced since 1981 by a pattern of a large number of relatively short stays. Rates of continuous hospital stay have increased in remote rural areas. However, relative decreases in length of continuous hospital stay have been roughly the same in urban and remote rural areas.
Three possible reasons related to patient behavior, diagnosis, referral, and management exist for the low standardized ratios of mortality and hospital discharge and high rates of MH+ in remote rural areas. First, in rural areas delays may occur in patient referral or, in the case of emergencies, delays in the provision of treatment. Such delays may be delays in a patient receiving treatment after presentation at a general practitioner, or in the case of an emergency, after calling for help and/or admission to a hospital. This is a delay in the provision of service. Second, rural inhabitants may delay before contacting health services. This is a delay caused by patient behavior, resulting in presentation at more advanced stages of heart disease. Cancer patients living in rural areas have more advanced stages of disease at diagnosis,8,25 and settlement remoteness confers a greater disadvantage than does small settlement size.26 We found that this disadvantage may also hold for IHD. Delay in contacting health services is of primary concern in the case of patients living in remote areas. The median door-to-needle timethe time required for a patient to receive thrombolytic treatment after arrival at a hospitalin the United Kingdom was halved during the 1990s.27 However, the resulting reduction in delay from the onset of symptoms to treatment was small because of increases in patient-caused delays.28 Early thrombolytic treatment is known to reduce premature acute myocardial infarction mortality and subsequent morbidity rates; therefore, delay in presentation affects patient survival of acute myocardial infarction and hence IHD. A number of social or cultural factors, including level of knowledge and distance to the nearest health service, may influence delay. Third, significant differences among different rurality categories may exist in provision of care or aftercare and length of stay in the hospital. Shorter continuous hospital stays may result in higher mortality rates after discharge because of insufficient treatment, whereas longer stays, particularly very long stays, increase the chance of mortality in the hospital. Hospital policies regarding beds and patient stays clearly influence this outcome.
These explanations suggest that IHD mortality may be avoidable. Other possible explanations for high rates of MH+ do not suggest avoidable mortality. The first is that IHD manifests itself in a number of forms, some more lethal than others. Rural inhabitants admitted to hospitals may have higher rates of acute myocardial infarction than other populations; the hospital discharge data we used do not detail the type of IHD. Rates of co-morbidities and complications may be higher in the rural than in the urban population. A second possibility is that diagnostic coding might vary systematically across rurality categories, resulting in deceptively high rates of MH+ in rural areas. However, such false positives are unlikely, because the data collected by the Information and Statistics Division in Scotland are considered to be of high quality.29
The multilevel models showed that, unlike mortality rates or hospital discharge rates, rates of MH+ have little to do with socioeconomic deprivation, and much of the variation among categories of rurality is among health boards. Moreover, populations served by rural boards have higher rates of MH+ compared with those served by urban boards. Multilevel analysis is able to attribute variation to different levels,30 and allowed us to distinguish between differences arising at the administrative (health board) level and small-area variation.
The socioeconomic deprivation indicator used in this study, the Carstairs index, has been criticized for being biased toward urban communities.31 This index includes components, such as car nonownership and overcrowding, that may be inappropriate for the measurement of rural deprivation. If the Carstairs indicator measured deprivation in urban areas but not in rural areas, the impact of deprivation on IHD in rural areas may have been underestimated, possibly resulting in an overestimation of the effect of rurality category on all 3 health outcomes.
The main limitation of this study was in the interpretation of findings. We have summarized the possible interpretations of our findings. However, further research is needed to ascertain whether the urbanrural differences result from differences in patient-caused delay, management of patients, or quality of health care.
It is clear from this study that much of the variation in rates of MH+ among populations served by different health boards remains unexplained, even when demographics, socioeconomic status, and rurality are taken into account. Rates of MH+ are particularly high in areas served by rural health boards. The target recommended by the National Services Framework3260 minutes as the maximum time between a call for help and receipt of thrombolytic treatmentis unlikely to be achievable in remote rural Scotland unless prehospital delivery of drugs becomes common practice. The Remote and Rural Areas Resource Initiative, funded by the National Health Service of Scotland to develop healthcare services and support for professional staff in remote and rural parts of Scotland, has initiated projects to train general practitioners and paramedics in the administration of prehospital thrombolysis. Benefit in pre-hospital treatment particularly is conferred when people live some distance from the nearest hospital,33,34 and general practitioners can help in the management of patients with suspected acute myocardial infarction.35 Having general practitioners who are located more than 30 minutes traveling time from any hospital provide thrombolysis has been associated with increased survival36 and has been shown to be cost effective37; methods of motivating general practitioners to do so are needed. Such provision may improve rates of MH+ in remote areas of Scotland, particularly in areas served by rural boards, where rates of MH+ are high.
Health promotion initiatives encouraging a healthy lifestyle will aid in reducing rates of of IHD. The National Services Framework32 established the need to target the population most at risk for IHD. In rural areas, programs must be tailored to the needs of rural communities. Information about symptoms, disease management, and access to services, including the first point of contact, would be particularly useful in the rural context, not only for the public but also for health care professionals, and can be provided by advice lines, outreach support groups, and Web sites.38
| Acknowledgments |
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Human Participant Protection
No protocol approval was needed for this study.
| Footnotes |
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Contributors
K. A. Levin originated the study, carried out the analysis, interpreted findings, and led the writing. A. H. Leyland assisted with writing, analysis, and interpretation.
Accepted for publication December 24, 2004.
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