1997 Spanish Nephrology Association (Sociedad Española de Nefrologia) Report on Dialysis and Transplantation

Spanish Nephrology Association Registry Committee:, J. J. Amenábar, F. García-López, N. R. Robles, R. Saracho, Regional Registries: Andalusia:, M. Calero, M. A. Gentil, Aragón:, M. J. Aladren, Asturias:, E. Martín-Martinez, Balearic Isles:, J. Bestard, J. Marco, Canary Isles:, V. Lorenzo, Cantabria:, A. L. Martín de Francisco, Castilla-La Mancha:, T. Sierra, Castilla y León:, A. Rodrigo, Catalonia:, M. Clèries, E. Vela, Extremadura:, N. R. Robles, Galicia:, F. Otero, La Rioja:, A. Sánchez-Casajús, Murcia:, M. Rodríguez-Gironés, Navarre:, C. Solozábal, Basque:, A. Magaz, Valencia:, M. J. García-Blasco, O. Zurriaga, Pediatric Registry:, I. Zamora and A. Vallo

Correspondence and offprint requests to: Dr Nicolás Roberto Robles, Servicio de Nefrología. Hospital Infanta Cristina, Carretera de Portugal s/n, E-06080 Badajoz, Spain. E-mail: nroblesp{at}meditex.es

Introduction

Traditionally, the Sociedad Española de Nefrologia Report on Dialysis and Transplantation has been drawn up on the basis of the data directly submitted by the Spanish dialysis and transplantation centres to the ERA–EDTA Registry. The response rate of these centres to the ERA–EDTA Registry has been falling every year (61% in 1996) [1]. Consequently, the reliability of the data has become a concern for the SEN Registry Committee. To overcome this problem, the SEN Registry Committee has modified the procedure to obtain the data, making use of the disinterested collaboration of Spanish Regional and Paediatric Registries, which achieve higher rates of response in their own areas (frequently near 100%).

This report has three parts. First, it presents the currently most accurate estimate of the incidence and prevalence of renal replacement therapy (RRT) in Spain in 1997. Also shown are the modalities of RRT used and the annual mortality for that year. Second, it presents the 1997 RRT data of paediatric patients. Third, it pools the data of five Spanish regional registries with a 100% centre response rate to study the trends of RRT in Spain during the interval 1990–1996, both years included.

Methods

Part 1. 1997 Demography of RRT in Spain
The data presented in this report correspond to the year 1997. They were obtained through a questionnaire returned either to Regional Registries (Andalusia, Asturias, Basque, Canary Isles, Catalonia, Galicia, Valencia) or a Regional Coordinator of the SEN Registry Committee (Aragon, Balearic Isles, Cantabria, Castilla-La Mancha, Castilla-León, Extremadura, La Rioja, Murcia, Navarre) who centralized data collection inside each area. Only Madrid remains outside of this organization, so that data of this region were not included in our results, which cover 87% of the Spanish population.

The questionnaire requested global information for each region on the number of patients on RRT on 31 December 1997, and the number of patients starting RRT during that year, including information on the modality of RRT in both cases. The number of deaths during 1997 for each modality of treatment was also requested. The questionnaire asked for information on the region where the patients usually lived. After receiving and processing the data, information concerning patients who lived in one area, but were treated in another one was submitted to each regional Registry and Coordinator. In this phase, the collected information was checked and compared.

Data on incidence and prevalence are expressed as absolute values and as patients per million population (p.m.p.). Data on the Spanish population come from the official census as of May 1996, published by the Instituto Nacional de Estadística [2].

Part II. RRT in paediatric patients
The Spanish Pediatric Registry (Registro Pediátrico de Insuficiencia Renal Crónica, REPIR) has collaborated in offering specific information about paediatric patients. Nineteen centres all over Spain (100% of paediatric nephrology units) reported to REPIR. Data on incidence and prevalence are expressed as absolute values and as patients per million of the paediatric (<20 years old) population.

Part III. Age, aetiology of renal failure and causes of mortality
Data collected by five regional registries with a 100% response rate (Andalusia, Basque Country, Canary Isles, Catalonia, Valencia) between 1991 and 1996 (Canary Isles from 1994) were pooled to study the age, aetiology of chronic renal failure and the causes of death of patients on RRT in Spain. These five registries cover about one half of the Spanish population (more than twenty million people). Data on incidence and prevalence are expressed as absolute values and as patients per million population. The rates were adjusted for age in order to allow comparison among the regions.

Results

Part I. 1997, Demography of RRT in Spain
During 1997, 3814 patients started RRT in Spain (114 p.m.p.). On 31 December 1997, 25689 patients were living on RRT (745 p.m.p.): 54.7% were being treated with haemodialysis, 5.1% with peritoneal dialysis and 40.2% had a functioning graft (Figure 1Go); of this number, 2418 patients died. This represented an annual increment of 1396 patients on RRT (5.7%).



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Fig. 1. Absolute figures of patients starting RRT, transplanted patients and deaths are shown.

 
There were 1861 kidney transplants performed (47 p.m.p.) [5], 17 of them as the first treatment modality (0.4%).

Overall mortality was 8.6%, i.e. 14.7% in peritoneal dialysis, 12.5% in haemodialysis and 1.7% in transplant patients.

Part II. RRT in paediatric patients
Forty-one patients aged under 20 years started RRT (4.5 p.m.p.). On 31 December 1997, 289 pediatric patients were on RRT in Spain (31.7 p.m.p.). Patients aged between 6 and 14 years had the highest incidence (46%) and prevalence (53%). The most common aetiologies of renal failure in patients starting RRT were hereditary and congenital nephropathies (incidence 31.7%), although the most frequent aetiology in prevalent patients was chronic pyelonephritis (32.2%).

Although most of the patients starting RRT were put on peritoneal dialysis, kidney transplantation was the most frequent treatment modality (74%). Sixty new kidney transplantations were performed on paediatric recipients. Seven children received a kidney graft without starting dialysis (pre-emptive transplantation).

Part III. Age, aetiology of renal failure and causes of death
The incidence and prevalence of RRT in patients under the age of 65 years showed little change with time. On the other hand, the incidence and prevalence of patients over 65 years of age showed a strong increase every year from 1991 to 1996 (Figures 2 and 3GoGo).



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Fig. 2. Age distribution of patients starting RRT against the time. Greatest growth has occurred in patients older than 65.

 


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Fig. 3. Age distribution of all patients in RRT as a function of time. The increment in prevalence rates is mainly due to a high acceptance of older patients (>65 years old).

 
Diabetic nephropathy has become the most common cause of renal failure (19% of cases in 1996). Vascular nephropathies had the second highest incidence (15%). Although glomerulonephritis, chronic pyelonephritis and cystic diseases are less common, their incidence, given as per million population, has not changed over this time. The aetiology is shown in Figure 4Go.



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Fig. 4. Diabetes has become the most common aetiology of chronic renal failure.

 
The most common causes of death in dialysis patients were cardiovascular disease (53% in 1996) and infectious disease (16%) (Figure 5Go). In transplanted patients infections were more frequent as the cause of death (23% over the period 1991–1996), though cardiovascular diseases were still the first cause (30%) (Table 1Go).



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Fig. 5. Causes of death of dialysis patients in 1996: cardiovascular diseases are the main cause of death.

 

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Table 1. Mortality of RRT patients in the EUa
 
Discussion

In the comparison of our data with those of other countries we used as references the 1998 USRDS Report [3] and the latest preliminary ERA–EDTA Registry Report [4]. The USDRS Report includes 1996 data and ERA–EDTA Report gives the 1995 data of European Union (EU). In comparing with EU data, we have only used the data from countries with response rates higher than 80%. Values are shown in Table 2Go.


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Table 2. RRT in the European Uniona
 
When we compared the Spanish incidence data with the data of the EU [4], Spain seems to be slightly below the EU average with respect to the incidence of new RRT patients (131 p.m.p.) and very far from the US figures where the incidence was 268 p.m.p., twice the EU incidence. The second most striking difference of Spain in relation to the EU is the low figure for patients who choose peritoneal dialysis as first modality of RRT (Spain 11.2% vs EU 15.8%).

The mean prevalence of patients on RRT in the EU was 700 p.m.p. on 31 December 1995, ranging from 444 p.m.p. in Finland to 773 p.m.p. in Italy. The prevalence of RRT in Spain was the third highest of the EU countries, after Italy and Germany. Spain had a higher than average rate of patients living with a functioning graft (EU mean 25.8%) which is related to the persistently high rate of organ donation obtained by the Spanish Organizacion Nacional de Trasplantes, the highest of all European countries [5]. Nevertheless, some countries such as Ireland or Finland have percentages of transplanted patients that are even higher than in Spain. Peritoneal dialysis is also more common in Spain than in other European countries.

Looking at the USRDS data, the USA prevalence of patients on RRT (1041 p.m.p.) was higher than the Spanish and European ones. Nevertheless the prevalence of RRT in the American white population (754 p.m.p.) was very close to the European value. The distribution of treatment modalities was very similar in the USA (peritoneal dialysis 14%, kidney transplant 27%) and in the EU.

Spain has the highest rate of transplantation of the EU countries (mean 28 p.m.p., ranging from 14 p.m.p. to 37 p.m.p.), in spite of the low rate of living donor transplants performed. The USA transplant rate was very close to the Spanish one, but the living donor transplantation rate was very high (14 p.m.p.). In Europe, only Scandinavian countries have living donor transplantation rates higher than 10 transplants p.m.p. [6].

Overall mortality in the EU (1995) was 10% (peritoneal dialysis 19.3%, haemodialysis 11.7%, transplanted patients 2.5%). Again, Spain is very close to the average European mortality rate, which is lower than the rate reported by the USRDS (23%). Any comparison between these data should be examined with circumspection, since no adjustment has been made for such factors as gender, age or aetiology of chronic renal failure.

The Spanish incidence and prevalence rates of pediatric patients are lower than Amerian ones (incidence 13 p.m.p., prevalence 64 p.m.p.). The figure is very close to paediatric incidence and prevalence rates reported from European countries [79].

An increasing acceptance of geriatric (older than 65 years) patients is a common trend in all developed countries [3,8,9]. As patients become older, diabetic and vascular nephropathy become the most frequent aetiologies of chronic renal failure [3,8,10,11]. The distribution of causes of death is very close to other developed countries [3,8,9].

Although the data collected by these five regional registries does not cover the entire Spanish population, they do cover more than one half of the country's population and so their results can be considered as a representative sample of Spanish RRT demography. Indeed, the incidence of diabetic nephropathy as a cause of chronic renal failure is not different from the data published by other Spanish regions [12].

Conclusions

Incidence, prevalence, aetiology and mortality of RRT patients in Spain are very close to the figures of other countries of the EU and lower than the USRDS data. Cadaver donor transplant programmes are more active in Spain than in the rest of the EU countries and this leads to a higher percentage of patients living with a functioning cadaveric graft.



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Fig. 6. Pooled causes of death of transplant patients from 1991 to 1996. Although cardiovascular diseases are still the most common cause of death, the incidence of infectious diseases is now higher.

 
References

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