1 Azienda Ospedale di Lecco, A. Manzoni Hospital, Lecco, Italy, 2 Department of Internal Medicine, Latvian Medical Academy, Riga, Latvia, 3 Clinic of Nephro-urology, Department of Nephrology, Vilnius University Santariskes Hospital, Vilnius, Lithuania, 4 Dialysis Unit, Tallinn Pelgulinna Hospital, Tallinn, Estonia, 5 Department of Internal Medicine, University of Tartu, Tartu, Estonia, 6 Department of Nephrology, University of Heidelberg, Heidelberg, Germany
Abstract
Introduction. The epidemiology of end-stage renal disease (ESRD) and renal replacement therapy (RRT) is under continuous evolution all over the world. Of particular interest is the development of RRT in the countries of the former Soviet bloc which underwent great political and socio-economical changes in the last decade. We report here the epidemiological analysis of ESRD and RRT in the three Baltic countries: Lithuania, Estonia, Latvia.
Subjects and methods. This epidemiological report is based on data from centre questionnaires which were collected from 1996 onwards, with a response rate of 9899%.
Results. The prevalence/incidence of RRT patients in 1999 were 213/99.5 p.m.p. in Lithuania, 186/45.5 p.m.p. in Estonia and 172/55.8 p.m.p. in Latvia. Haemodialysis (HD) was the most common RRT modality in Lithuania (60% of prevalent patients), but not in Estonia (29%), while in Latvia it was nearly as common as renal transplantation (45 and 46%, respectively). Home HD was not performed. The proportion treated by peritoneal dialysis (PD) was very low in Lithuania (4% of RRT patients), while the percentage was higher in Latvia (9%) and Estonia (20.4%). The percentage of patients on RRT treated by renal transplantation was high throughout, representing the main modality of treatment in Estonia (50.5% of RRT prevalent patients, 94 p.m.p.) and in Latvia (46%, 79 p.m.p.) and being high in Lithuania (36%, 77 p.m.p.). The main renal diseases leading to ESRD were glomerulonephritis, pyelonephritis and diabetes.
Conclusion. The epidemiology of RRT in the Baltic countries is undergoing rapid changes. Transplantation has reached an impressive level. A high percentage of RRT patients live with a functioning graft.
Introduction
The epidemiology of end-stage renal disease (ESRD) and renal replacement therapy (RRT) is under continuous evolution all over the world. In the Western countries, an increase in the prevalence of RRT (dialysis plus transplantation) has been observed over the recent past years [1], due partly, to decreased mortality but, above all, to the increase in the incidence rate, which is mainly accounted for by the increased acceptance of diabetic and older patients.
Profound political and social changes have taken place in Eastern Europe in the last decade and the countries of the former Soviet bloc are undergoing rapid economic development. The issue of how to best provide RRT, both from the clinical and socio-economical points of view, has become a major issue in such nations. The European Renal Association (ERA) and the International Society of Nephrology (ISN) perceived this demand and founded the Joint Action Nephrology in Eastern Europe, with the aim of supporting the growing know-how in nephrologic care and RRT in those countries. In this context, starting in 1992, a series of Baltic Nephrology Conferences was organized in collaboration with the Baltic National Associations of Nephrology. These interactive sessions were designed to offer the opportunity to local nephrologists to discuss important general issues and practical topics with experts from abroad.
We present here the epidemiological analysis of ESRD in the Baltic countries (Lithuania, Estonia, Latvia), which was presented and discussed at the Vth Baltic Nephrology Conference in Tallin, Estonia, June 30July 2, 2000.
Subjects and methods
This epidemiological survey is based on data from centre questionnaires. Data collection was started in 1996 under the responsibility of the chief of each centre or the senior nephrologist of each unit. The national co-ordinator checked the data again to find out contradictions or incongruity. The overall percent response rate was 9899%. Patients were included in the analysis from their first dialytic treatment.
Results
The principal epidemiological data are summarized in Table 1. The highest prevalence rate of patients undergoing RRT in the Baltic countries up to December 31, 1999 was recorded in Lithuania (213 p.m.p.), compared with Estonia and Latvia (186 and 172 p.m.p., respectively). When considering the incidence data, the greatest acceptance rate to RRT was again recorded in Lithuania (99.5 p.m.p.), while it decreased in Latvia (55.8 p.m.p.) and Estonia (45.5 p.m.p.). The epidemiological trend of RRT over the recent past years was available in Lithuania and Estonia from 1996 for prevalence data and from 1997 for incidence data, while in Latvia both prevalence and incidence were available from 1998. The prevalence rate increased in all three Baltic countries: in Lithuania from 153 p.m.p. in 1996 to 213 p.m.p. in 1999; in Estonia from 138 p.m.p. in 1996 to 186 p.m.p. in 1999; and in Latvia from 157 p.m.p. in 1998 to 172 p.m.p. in 1999. The incidence rate increased in Lithuania and Latvia: in Lithuania from 72 p.m.p. in 1997 to 99.5 p.m.p. in 1999 and in Latvia from 52 p.m.p. in 1998 to 55.8 p.m.p. in 1999. However, it remained constant in Estonia (45.5 p.m.p. in 1997, 34.5 p.m.p. in 1998 and 45.5 p.m.p. in 1999). The increased prevalence of RRT observed in Estonia in the recent past years was due to a decreased mortality (from 19.5% in 1997 to 17% in 1999). Mortality recorded in Latvia in 1999 was even lower (13.5%). Unfortunately, data concerning mortality trend over the recent past years were not available from Lithuania and Latvia.
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The proportion of patients treated by peritoneal dialysis (PD) was very low in Lithuania (4% of RRT patients), while it was distinctly higher in Latvia (9%) and Estonia (20.4%). In any case, PD was the least common RRT modality in the three Baltic countries. The great majority of PD treatments was accounted for by continuous ambulatory PD (ranging from 80 to 90%), but automatic PD was performed as well. The percentage of RRT patients treated by transplantation was high. It represented the main treatment modality in Estonia (50.5% of RRT prevalent patients, 94 p.m.p.) and Latvia (46%, 79 p.m.p.). It was also frequent in Lithuania (36%, 77 p.m.p.).
The main underlying diseases leading to ESRD are summarized in Table 2. Glomerulonephritis, pyelonephritis and diabetes were the most important causes of ESRD.
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Discussion
Since dialysis and renal transplantation became available in the 1960s, the implementation of the RRT programmes not only reflects the state of the art in medical knowledge and available medical and technical possibilities, but is also related to socio-economic conditions of a community. In fact, the demand on resources and social assistance by RRT patients is a challenge for the healthcare systems of all nations. Its implementation requires an economy which is sufficiently developed to support it. The differing distribution of RRT patients in the world is strongly influenced by the level of the gross domestic product, and economic problems impact on the number of patients starting RRT [2]. This explains why the inclusion criteria for patients entering RRT are variable from country to country and, at least in part, are context-dependent.
The collection of data on patients undergoing RRT, i.e. renal registries, was started years ago in the Western countries. International, national and regional renal registries have been established, such as the EDTA-ERA [3], the United States Renal Data System (USRDS) [4], and the Dialysis and Transplant Patients Lombardy Registry [5]. This has provided an important tool to recognize the many factors that influence the delivery of nephrology care and patient outcome. A remarkable example of how much the analysis of registry data can lead to improved management of RRT patients was provided by the comparison of registry data from the USA (USRDS) with Europe (particularly Lombardy) and Japan. The reports on documented higher mortality in USA dialysis patients, mainly associated with a shorter dialysis time [68], led to a prolongation of the duration of dialysis sessions in the USA.
The importance of collecting RRT patients' data has been perceived by nephrologists in the Baltic countries as well, and led to the ongoing establishment of official national registries. This followed the recognition that in years of an expanding delivery of RRT, planning of health services must be based on solid quantitative information. The prevalence of patients undergoing RRT in the Baltic countries has been increasing recently, but figures are still in a low range (<250 p.m.p.) compared with the very high figures recorded in Japan and the USA (>1000 p.m.p.) and the figures in an intermediate range reported from other European and American countries (400800 p.m.p.). The figures of the Baltic countries are, however, not far from those recorded in neighbouring Poland and are higher than those recorded in Romania and Russia (Figure 1) [1,9].
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Systematically collected data concerning prevalent and incident patients with information on age distribution and co-morbidity (particularly cardiovascular) are currently not available in the Baltic registries. This is a target for the future to improve the quality of the registries and to provide instruments which are better suited for the aim to provide assistance to the health authorities for the planning of optimal RRT programmes within the available resources.
One of the most remarkable observations from the analysis of RRT modalities in the Baltic countries is the high percentage of RRT patients with a functioning renal graft (Figure 3), which is far higher than the mean percentage of 22% in the 14 countries of Eastern Europe, as reported by Rutkowski [9]. When comparing the relative importance of renal transplantation in the Baltic countries with that of other Western European countries [10] (Figure 4
) it is obvious that, similarly to what is observed in the United Kingdom and Holland, renal transplantation in Estonia and Latvia is the main RRT modality, in contrast to Italy, Germany, Spain, France and Lithuania, where HD is prominent. Nevertheless, the number of patients living with a functioning transplant per million population is still low (<100 p.m.p.). The high transplantation rate is presumably a delayed reflection of the situation during the years of Soviet government when dialysis equipment was scarce, so that the development of an active transplantation programme was the only option to save lives.
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As far as the underlying disease leading to ESRD in incident patients is concerned, the Baltic registries have the same problems as other European registries, that is a high degree of imprecision. Nosography must remain vague in an environment where the criteria for performing renal biopsies are variable and clinical diagnoses are uncertain, not least because of the well-known problem of late patient referral to nephrologists. Given these limitations, glomerulonephritis and pyelonephritis were the most frequently reported causes of ESRD in the Latvian incident cohort (only data on prevalent patients were available from Lithuania and Estonia).
Diabetes as a comorbid condition in ESRD patients was reported in 11% of the incident Latvian patients, and 17.8% and 16.2% of the prevalent Estonian and Lithuanian patients. These values are not far from what has been observed in some other European countries, including neighbouring Poland (where in 1998, 11.7% of RRT patients were recorded as diabetics) [9], but less than the percentage of diabetic ESRD patients reported from the USA and Germany (around 40%) [4,13], or from the Czech Republic (33%) [9]. These differences are not only the results of different acceptance rates to RRT, but may also be determined by true differences in the frequency of type 2 diabetes, which accounted, at least in part, for the catastrophic increase in diabetic nephropathy world-wide [13]. The varying frequency of type 2 diabetes is determined, to a variable extent in the different countries, by factors, such as diet and duration of life, as well as genetic background.
Hypertension/vascular disease represents a less frequently reported cause of ESRD (about 5%) as compared to the USA (26%) [4] and Italy (22%) [12], but this difference is probably an artefact, reflecting differences in habits to classify renal diseases on clinical grounds or, more likely, differences in the mean age of patients accepted to RRT.
It is worth drawing attention to a recent report of the results of 600 renal biopsies performed in Lithuania from 1995 to 1999 [14]. The most commonly diagnosed types of glomerulonephritis (GN) were IgA nephropathy (30%), membranoproliferative GN (23%), and mesangioproliferative GN (13%). Secondary forms of GN were diagnosed in 14% and tubulointerstitial diseases in 8% of the biopsies.
In conclusion, the epidemiological panorama of RRT in the Baltic countries is undergoing a rapid change, compared with previous reports in the last decade [15,16] and with the international situation.
Acknowledgments
Part of the data incorporated in Figures 1, 2
, 3
have been supplied by the United States Renal Data System (USRDS) [1,4]. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy or interpretation of the US Government. Part of the data incorporated in Figures 1
, 2
, 3
, 4
were taken from references [9,10,12]. We would like to thank all nephrologists from the Baltic countries for their collaboration in filling in the epidemiological questionnaires.
Notes
Correspondence and offprint requests to: Prof. Dr Francesco Locatelli, Department of Nephrology and Dialysis, Ospedale A. Manzoni, Via Dell'Eremo 11, I-23900 Lecco, Italy.
References