Q J Med 1999; 92: 637-642
© 1999 Association of Physicians
Equity of renal replacement therapy utilization: a prospective population-based study
From the Department of Medicine and Therapeutics, University of Aberdeen, Aberdeen, UK
Received 19 March 1999 and in revised form 25 August 1999
Dr W. Metcalfe, Department of Medicine and Therapeutics, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD
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This 1-year prospective survey assessed the incidence and characteristics of all patients starting renal replacement therapy (RRT) for end-stage renal disease in Scotland, and whether there is equity of utilization of RRT in terms of age, domicile and social circumstance. In the year studied, 104 patients per million population (533 patients) started RRT (390 per million population aged 65–75). In 23.5% the cause of ESRD could not be determined. Diabetes was the single most frequently identified cause (16%). The requirement for RRT rose with age, but over the country as a whole, patients aged over 75 years were under-represented. The majority of health boards provided RRT at a rate within 20% of the national rate. There was no difference in the median age at starting RRT between health boards. The spectrum of social deprivation of patients starting RRT was the same as that of the general population. There was no evidence that social deprivation influences acceptance on to the RRT program, although the relationship between ESRD and deprivation is complex. The utilization of RRT exceeded the minimum rate recommended by the Renal Association, although there was fluctuation between health board areas. The national requirement for resources to provide RRT is likely to rise further to care for an increasingly elderly population.
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Introduction |
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Renal replacement therapy (RRT) in the form of dialysis or transplantation is an expensive but life-saving treatment for end-stage renal disease (ESRD). In 1967, the RRT requirement in Scotland for patients aged under 65 was reported as 52 per million of the population per annum, only one quarter of whom were offered treatment.1 At that time patients aged over 65 and those with extra-renal comorbid illness were denied treatment. A study from England in 1989 suggested that 78 per million population required and were suitable for RRT, but only 52 per million received treatment. Patients with malignancy, including myeloma, were considered unsuitable and excluded from these figures.2 Data from the Scottish Renal Registry show that 62 new patients per million population started RRT in 1989. The shortfall between utilization of RRT in Britain and the predicted underlying need has previously been investigated. Referral of patients with chronic renal failure (CRF) to a nephrologist for RRT diminishes the further they live from a renal unit, particularly in the case of elderly patients.3,4 Elderly patients are also less likely to be referred to a nephrologist irrespective of where they live.2,5 Feest et al.2 reported that 51% of patients aged 60–80 years with advanced CRF were not referred to a nephrologist. Recent evidence suggests that patients with comorbid illness are less likely to be referred for dialysis,5 and some patients with CRF whom nephrologists would consider suitable for RRT might still be assumed unsuitable by non-nephrologists and general practitioners.6 Equity of access to NHS services is a national priority. For valid comparisons of service provision and treatment outcomes, however, adjustment must be made for patients age, gender, deprivation, prior morbidity and case mix.7 The independent inquiry into inequalities in health (England) highlighted the difficulties in examining the relationship between socio-economic variations in health and equity of health care.8 To accommodate the difficulties involved in the comparison of treatment rates or outcomes between individual health boards, the catchment population of each must be defined. This paper reports a prospective study of all patients commencing long-term RRT in all adult renal units in Scotland over a year. The study aimed to define the characteristics of the current incident population requiring RRT and to ascertain whether there was equity of utilization of RRT in terms of age, geography and social circumstance across Scotland's health board areas.
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Between 1/10/1997 and 30/9/1998, all adult patients starting RRT for ESRD in Scotland's eleven adult renal units were registered by one of us (WM). Patients were identified by weekly contact with a liaison person in each unit. A monthly check list was circulated to ensure no omissions had occurred. No patient with an English postcode started RRT in Scotland during the year studied, and no patient with a Scottish postcode started RRT in Carlisle (personal communication). The data routinely collected by the Scottish Renal Registry were augmented by data collected on site from patients, case notes and renal unit computer systems where available, and were entered directly on to the Registry via a secure modem. Patients were registered on the day they started RRT. Those failing to recover from presumed acute renal failure were registered when the physician caring for them considered they would require permanent dialysis. Some patients unexpectedly recovered renal function. In Britain there is no standard duration of RRT before which treatment is considered acute rather than chronic; in the USA after 90 days patients are considered to have ESRD. We adopted this definition and excluded patients who recovered renal function during the first 90 days but not those who died. The patients age on the day they started RRT was calculated. For the purposes of analysis, the patients were divided into quartiles according to age and then bracketed into four age groupings which most closely encompassed those quartiles: 15–49 years, 50–64 years, 65–75 years and >75 years. Primary renal diagnoses were coded according to the European Dialysis and Transplant Association-European Renal Association Registry codes. Population information was taken from mid-1997 estimates published by the Registrar General for Scotland.9 Social deprivation was measured by means of the Carstairs score which is derived from car ownership, male unemployment, overcrowding and social class.10 The data for correlation of postcodes to health board areas and Carstairs codes were obtained from `Carstairs Scores for Scottish Postcode Sectors from the 1991 census'.11 The incidence of new patients in each health board was compared with the national rate by incidence ratio: (observed patients/expected patients)x100, where expected=national ratexpopulation of health board. Confidence intervals were calculated for each ratio.12 Data were analysed using SPSS 8.0 for Windows 95. Data were found to be non-normally distributed, and non-parametric tests were therefore used throughout. A 5% level of significance was used.
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Results |
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We identified 542 patients, of whom nine recovered renal function becoming independent of RRT within 90 days and were excluded from further analysis. Of the remaining 533 patients, 517 (97%) were Caucasian, 319 (60%) were male, and the median age was 64.6 years (range 15.6–91.4 years). The 533 patients represented 104 adult patients per million of the population (5 122 500, mid-1997 estimate), or 128 patients per million of the population aged over 15 years (4 166 641). Twenty-nine patients (5.4%) were aged 80 years or over on the day they started RRT; of these, two patients were in their nineties (Table 1
). Diabetes was the most commonly identified single cause of ESRD, followed by glomerulonephritis. A definite diagnosis could not be made in 23.5% of patients, either because of contraindications to renal biopsy or the presence of bilateral small scarred kidneys where biopsy would yield no useful tissue for diagnostic purposes. (Table 2). The relevant health board was identified by patient's home postcode (not the location of their treatment centre). The incidence ratio of new patients starting chronic RRT in each of Scotland's 15 health board areas was compared with the national rate (Table 3). In all but one (Dumfries and Galloway), the incidence was no different to the national rate as shown by the inclusion of 100 in the 95% confidence intervals, although the confidence intervals are very wide for those areas with low populations. In all but five areas, the incidence rate ratio was within 20% of the national rate and two of these areas (Western Isles and Orkney) have small populations. The incidence was 22% below the national rate in Highland health board region, was 28% below in Fife and 70% above in Dumfries and Galloway. Carstairs deprivation scores were obtained for all patients from their home postcode and the spectrum of deprivation scores of patients starting RRT was the same as that of the general population (Table 4). The median ages at the start of RRT ranged between health board areas from 57.2 years in Highland to 68.4 years in Orkney. The difference was not statistically significant (p=0.303 Kruskal Wallis: 
2=16.169, df=14).
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The geography of Scotland and the dispersal of its population complicates the provision of specialist services. We have demonstrated that RRT is utilized across Scotland within 20% of the national rate in all but five health board areas. The Western Isles and Orkney do not lie within this band, but have small populations and are geographically isolated, with renal services provided on mainland Scotland. Previous studies have shown that referral to nephrologists diminishes, the further patients live from a renal unit. The reasons for the low incidence in Highland and Fife and the high incidence in Dumfries and Galloway are not obvious. The findings in Fife have prompted investigation of the referral rate to renal services within the Fife health board area (personal communication). It is notable that two areas with large populations, Lothian and Lanarkshire, have relatively low incidence rates compared with all other areas with populations in excess of 250 000 people; further investigation of renal service provision within these areas may be warranted. Registry figures over the next few years will demonstrate whether such differences persist.
Mortality and morbidity are generally adversely affected by social deprivation.13,14 The Carstairs score reflects the material resources of residents of a postal area as a whole, rather than categorizing the affluence of individuals. Thus an affluent person living in a relatively deprived area is not accurately described by the Carstairs score assigned to them. Previous work in Grampian (an affluent area) showed no difference in social deprivation indices between those starting RRT and the general population.15 We confirm this finding for the entire country; the spectrum of deprivation scores in the incident RRT population is the same as that of the general population. Within Scotland, however, health board areas have different profiles of social deprivation with categories 6 and 7 (most deprived) comprising 49% of Greater Glasgow Health Board catchment area and 21% of Lanarkshire, but only 2% in Fife and not figuring at all in Highland or Borders areas.10 The areas of lower incidence of RRT in this study correspond to those with less social deprivation, i.e. Fife and Highland regions. A higher rate was not consistently observed in areas of excess deprivation; whilst Greater Glasgow Health Board had a rate of 118% of the national rate, that in Lanarkshire was only 82%. Referral patterns may explain this variation in incidence in deprived areas. The relationship between social deprivation and ESRD is unclear. The incidence of ESRD might be higher in more deprived areas if one speculates that social deprivation has an influence on the incidence of CRF. Of the population starting RRT, 9% had ESRD secondary to atherosclerotic renal artery disease. The risk factors for atherosclerosis are well recognized, and include being socially disadvantaged, smoking, high total serum cholesterol, hypertension and obesity.16 The demand for RRT in deprived areas however, may be diminished by patients who would have developed ESRD and require RRT, dying of other causes such as ischaemic heart disease before ESRD is reached. The incidence of diabetic glomerulosclerosis and hypertensive nephrosclerosis in White Americans is associated with declining socio-economic status, possibly due to lack of access to treatment for the causative disease.17 We feel that further study into the relationship between social deprivation and the incidence of ESRD in the population as a whole is merited. The annual incidence of RRT in Scotland in the year studied was 104 per million of the population. The age-specific rate peaked at 390 per million in the 65–75 age group but tailed off to 257 per million in those over 75. The incidence of advanced CRF however increases relentlessly with age, approaching 588 per million in those over 80.2 The relatively low proportion of elderly patients in the RRT population may reflect a continuing reluctance to refer such patients to nephrologists, which may be justified in many cases on the grounds of comorbidity. Two patients commenced RRT aged over 90 years, demonstrating that age alone need not be considered an absolute contraindication to RRT.
In 1997, the Renal Association recommended that a minimum of 80 per million population per year would be an appropriate rate for the new patients starting RRT, adjusted upwards as necessary for ethnic and age distribution.18 This figure is already exceeded across Britain. In England and Wales in 1995, the annual incidence of new patients was 82 and 109 per million respectively.19 In the USA in 1996, 199 per million of the White population commenced RRT for ESRD.20 Scotland and Wales have predominantly White populations. In England a higher requirement for RRT would be expected to take into account the higher incidence of chronic renal failure in Black and Asian ethnic groups.21
The most commonly identified primary renal diagnosis in the Scottish incident population is diabetes (16% of patients) although a diagnosis could not be made in 23.5% of patients. Scottish Renal Registry data show that until the mid 1970s, patients with diabetic nephropathy did not receive RRT in Scotland at all, but since that time the proportion of diabetics in the RRT population has continued to increase steadily. In the USA, diabetics account for 42% of incident patients; however Black and Asian populations together comprise 36% of the incident American dialysis population.20 Of patients in Scotland, 2.4% had ESRD secondary to myeloma and 9.2% secondary to atherosclerotic renal artery disease. Both of these groups of patients have high morbidity and mortality, and previously would have been less likely to receive RRT. The RRT population continues to be expanded by an increasingly aged, infirm and dependent population.
In conclusion, the utilization of RRT across Scotland fell within 20% of the national rate in 10 of the 15 health board areas in the year studied. There was no difference among health boards in the median age of patients when they started RRT although the older age group was still under represented across the country as a whole. Across Scotland, the distribution of deprivation in the incident patients is the same as that of the general population. The effect of the marked differences in deprivation between health boards upon the requirement for RRT is complex and requires further investigation. Our study shows that the Renal Association recommended minimum treatment rate of 80 patients per million population per annum is an under estimation of the true need for RRT in the UK. The dialysis population is increasingly aged and infirm with a higher incidence of multisystem diseases such as diabetes and atherosclerosis. An ageing population and equity of utilization of RRT will place ever greater demands on renal services in Scotland.
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Acknowledgments |
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We would like to thank the staff of Scotland's adult renal units for their help in executing this study and for commenting on the manuscript: Aberdeen Royal Infirmary; Crosshouse Hospital, Kilmarnock; Dumfries and Galloway Royal Infirmary; Edinburgh Royal Infirmary; Glasgow Royal Infirmary; Monklands Hospital, Airdrie; Ninewells Hospital, Dundee; Queen Margaret's Hospital, Dunfermline; Raigmore Hospital, Inverness; Stobhill Hospital, Glasgow; Western Infirmary, Glasgow. Initial statistical advice was given by Janet Squares, Research Fellow in Public Health, Aberdeen University. The study was funded by a grant from the Scottish Office Department of Health Clinical Resource and Audit Group (CRAG). The views expressed are those of the authors and not necessarily those of either the Scottish Office Department of Health or CRAG. The Scottish Renal Registry was funded jointly by all the Scottish Health Boards.
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