Slovenian Renal Replacement Therapy Registry: Excerpts from the 2008 Annual Report

Authors

  • Jadranka Buturović-Ponikvar,

    1. Department of Nephrology, University Medical Center Ljubljana, Ljubljana, Slovenia
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  • Jakob Gubenšek,

    1. Department of Nephrology, University Medical Center Ljubljana, Ljubljana, Slovenia
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  • Miha Arnol

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    • Members: Tone Adamlje, Danica Blanusa, Zlata Ceglar, Sonja Cimerman Steklasa, Andrej C̆ufer, Andrej Drozg, Robert Ekart, Andrej Guček, Aljoša Kandus, Sonja Kapun, Simona Kralj-Lopert, Stojan Kralj, Marko Malovrh, Marjan Močivnik, Gregor Novljan, Rafael Ponikvar, Nikola Rukavina, Igor Rus, Silvan Saksida, Živojin Stevanović, Bojan Vujkovac.


  • Presented in part at the Symposium Celebrating the 40th Anniversary of Chronic Dialysis and Kidney Transplantation in Slovenia, held 4–5 November 2010 in Bled, Slovenia.

Professor Dr Jadranka Buturović-Ponikvar, Department of Nephrology, University Medical Center Ljubljana, Zaloška cesta 7, 1525 Ljubljana, Slovenia. Email: jadranka.buturovic@mf.uni-lj.si

Abstract

This report provides a summary of the 2008 Slovenian Renal Replacement Therapy Registry Annual Report. Data on renal replacement therapy (RRT) were obtained from 20 dialysis centers and one transplant center, referring 31 December 2008, with 100% response rate to individual patient questionnaires. Slovenia has a population of approximately two million. The total number of patients treated by RRT was 1967, i.e. 968 per million of population (pmp), a 3.7% increase compared to 2007. In total, 1343 (68.3%) were treated by hemodialysis, 105 (5.3%) by peritoneal dialysis, and 519 (26.4%) had a functioning kidney graft. A total of 235 incident patients, 116 pmp (at day one), started RRT: their median age was 67 years, 61.8% were men, and 28% were diabetics. Regarding hemodialysis patients, 77% were dialyzed in hospital and 23% in private centers, 48% were treated with on-line hemodiafiltration and 74% with ultrapure dialysis fluid. The median weekly duration of hemodialysis was 13.5 hours, median dry body weight 68 kg, mean blood flow 283 ± 51 mL/min, and 9.2% were dialyzed using a single-needle mode. Vascular access was provided by a native arteriovenous fistula in 82%, a polytetrafluoroethylene graft in 6%, and a catheter in 12%. The crude death rate was 12.4% in dialysis patients, 1.4% in transplant recipients, and 9.4% in all RRT patients (both dialysis and transplant, incident patients at day 1 included). The longest survival on RRT is 38 years (with hemodialysis only). Slovenia has been a member of Eurotransplant since 2000; 52 kidney transplantations were performed in 2008, all from deceased donors.

The present report provides a summary on epidemiology and treatment practices in end-stage renal disease (ESRD) patients treated with renal replacement therapy (RRT) in Slovenia in 2008. The report is based on individual and center questionnaires prepared by the Slovenian Renal Replacement Therapy Registry Group. The response rate to the questionnaires was 100%. Pediatric data has also been included. More detailed data than those presented in this paper may be found in the Slovenian Renal Replacement Therapy Registry 2007 & 2008 Annual Reports(1).

Chronic hemodialysis program started in Slovenia in 1970. In the same year, the first kidney transplantation from a living related donor was performed. Annual reports on RRT epidemiology were initiated in 1999 and were prepared by the expert group for dialysis. These reports were initially based on data from renal center questionnaires (2,3). In 2002, we began collecting individual patient data as well, and by 2004 a response rate of 100% was achieved for individual patients. With these data, the Slovenian RRT registry joined the ERA–EDTA (European Renal Association–European Dialysis and Transplant Association) registry (Section B, aggregated data), and the Slovenian RRT Registry Group was founded, sponsored by the Slovenian Society of Nephrology (4,5). The registry is voluntary. In 2007, we joined with individual patient data to the European Society for Pediatric Nephrology (ESPN) Registry (6). The Slovenian RRT Registry has been a partner in the NephroQUEST study (7) and the Explaining the Variation in Epidemiology of Renal replacement therapy through Expert opinion, Secondary data sources and Trends over time (EVEREST) study (8,9).

The general population of Slovenia is approximately two million (2 032 362 in 2008: 1 028 417 women and 1 003 945 men).

RENAL CENTERS

On 31 December 2008, there were 21 renal centers in Slovenia (the same as in previous years): 15 in-hospital dialysis centers, five private outpatient hemodialysis centers (four of them owned by Fresenius Medical Care), and one transplant center. One of the 15 in-hospital centers is the Center for Pediatric Dialysis and Transplantation and another is the Center for Peritoneal Dialysis at the University Medical Center Ljubljana. Eleven out of the 15 in-hospital centers perform hemodialysis procedures for patients with acute renal failure. In addition to the specialized Center for Peritoneal Dialysis at the University Medical Center Ljubljana, peritoneal dialysis is also performed at eight in-hospital dialysis centers in Slovenia.

INCIDENT PATIENTS

Incident patients at day 1

There were 235 incident patients (incidence rate 115.6 per million population [pmp]); of these, 144 were men (61.3%, incidence rate 143.6 pmp) and 91 were women (38.7%, incidence rate 88.4 pmp). The age and gender adjusted incidence rate (with the general population of the EU27 in the year 2005 used for the adjustment calculation) was 113.7 pmp, for men 144.7 pmp, and for women 84.9 pmp. The mean age of the incident patients was 63.9 ± 15.1 years (median 67 years), the mean age of men was 61.3 ± 15.6 years (median 65.0 years), and the mean age of women was 67.2 ± 13.8 years (median 69.0 years).

The primary renal diseases in incident patients at day 1 in 2008 were: diabetic nephropathy type 1 4.3%, type 2 16.6%, both 20.9%; hypertension 11.1%; renovascular disease 1.3%; glomerulonephritis 12.8%; polycystic kidney disease 6.0%; pyelonephritis 5.1%; miscellaneous (other) 20.4%; and unknown 22.6%. Diabetes, as a comorbidity, was present in 65/235 (27.7%) of incident dialysis patients.

Incident patients at day 91

There were 228 incident patients alive and on RRT at day 91 (incidence rate 112.2 pmp), of these 141 were men (61.8%, incidence rate 140.6 pmp) and 87 were women (38.2%, incidence rate 84.5 pmp). The age and gender adjusted incidence rate (with the general population of the EU27 in the year 2005 used for the adjustment calculation) was 110.2 pmp, for men 141.7 pmp, and for women 81.2 pmp.

The mean age was 63.7 ± 15.2 years (median 67.0 years), the mean age of men was 61.6 ± 15.5 years (median 65.0 years), and the mean age of women was 67.1 ± 14.2 years (median 69.0 years). The primary renal diseases in incident patients at day 91 were almost the same as in incident patients at day 1.

PREVALENT PATIENTS

Data relating to prevalent ESRD patients on different forms of RRT are presented in Table 1. The annual increase in 2008, as compared to 2007, was 3.7%.

Table 1. Prevalence of end-stage renal disease patients for different forms of renal replacement therapy on 31 December in the period from 1998–2008 (residents only)
31 DecemberHemodialysisPeritoneal dialysisFunctioning graftAll
  • Based on individual patient data. Data are presented as N or N (%).

19989571212011279
199910001292301359
200010511172671435
200111251133041542
200211311103431584
200311711163741661
200412021194151736
200512601154271802
200612711034611835
20071318974821897
200813431055191967
Increase 199943 (4.5%)8 (6.6%)29 (14.4%)80 (6.3%)
Increase 200051 (5.1%)−12 (−9.3%)37 (16.1%)76 (5.6%)
Increase 200174 (7.0%)−4 (−3.4%)37 (13.9%)107 (7.5%)
Increase 20026 (0.5%)−3 (−2.7%)39 (12.8%)42 (2.7%)
Increase 200340 (3.5%)6 (5.5%)31 (9.0%)77 (4.9%)
Increase 200431 (2.6%)3 (2.6%)41 (11.0%)75 (4.9%)
Increase 200558 (4.8%)−4 (−3.4%)12 (2.9%)66 (3.8%)
Increase 200611 (0.9%)−12 (−10.5%)34 (8.0%)33 (1.8%)
Increase 200747 (3.7%)−6 (−5.8%)21 (4.6%)62 (3.4%)
Increase 200825 (1.9%)8 (8.2%)37 (7.7%)70 (3.7%)

On 31 December 2008, there were 1967 prevalent RRT patients in Slovenia with a prevalence rate of 968.0 pmp, 1130 men (1126.6 pmp) and 837 women (813.4 pmp). Men represented 57% of the prevalent RRT patients. The mean age of prevalent patients was 59.4 ± 15.2 years (median 61 years). The mean age of prevalent men was 58.7 ± 14.9 years (median age 60 years) and of women 60.3 ± 15.5 years (median 61 years).

The primary renal diseases in prevalent RRT patients in 2008 were: diabetic nephropathy type 1 4.5%, type 2 10.0%, both 14.5%; hypertension 7.5%, renovascular disease 0.9%; glomerulonephritis 23.5%; polycystic kidney disease 9.2%; pyelonephritis 10.6%; miscellaneous (other) 15.6%; unknown 15.0%; and missing data 3.4%.

The distribution of RRT modalities is presented in Table 2. The majority of prevalent RRT patients were treated with chronic hemodialysis. These patients were older and had a higher percentage of diabetics than patients treated with peritoneal dialysis or kidney transplantation. The longest duration of RRT is 38 years (hemodialysis only; the patient was still alive in February 2011).

Table 2. Patients treated with different forms of renal replacement therapy (RRT) in Slovenia on 31 December 2008
 No. of patients (% of all RRT)MenMedian age (years)Diabetic nephropathy/diabetesCrude death rate in 2008§
  • Residents only.

  • The presence of diabetes is collected separately as comorbidity data.

  • §

    § Incident day 1 included.

Hemodialysis1343 (68.3%)57%6618%/24%12.5%
Peritoneal dialysis105 (5.3%)61%5716%/23%9.1%
Transplantation519 (26.4%)57%535%/13%1.4%
All196757%6115%/22%9.4%

PREVALENCE AND INCIDENCE PER MILLION POPULATION

The number of prevalent patients per million population increases continuously. The number of incident patients per million population was relatively stable from 1998–2008 (Table 3).

Table 3. Number of unadjusted prevalent and incident (day 1) patients per million population (pmp) from 1998–2008
31 DecemberPrevalence pmpIncidence pmp
  • Based on individual patient data.

1998651
1999692115
2000723109
2001771144
2002807115
2003846131
2004869125
2005901125
2006913124
2007936118
2008968116

PEDIATRIC RRT PATIENTS

There were 22 prevalent patients aged 20 years or younger in Slovenia on 31 December 2008. Five of them started RRT in 2008, three with chronic hemodialysis and two with peritoneal dialysis. Out of the prevalent pediatric patients, seven pediatric patients had a functioning kidney graft from a cadaveric donor, eight were treated with chronic hemodialysis, and seven with peritoneal dialysis. The median age of the prevalent pediatric patients was 16 years (range 3–20 years). None of the patients died in 2008.

MORTALITY IN RRT PATIENTS

A total of 182 patients on RRT died in 2008 (incident [day 1] patients were included), of these 103 (57%) were men and 79 (43%) were women. Their mean age was 69.6 ± 11.4 years (median 72 years) and their mean RRT vintage was 5.8 ± 6.3 years (median 3.6 years). Of the deceased patients, 174 were dialysis patients (166 hemodialysis and nine peritoneal dialysis) and seven were kidney graft recipients.

The crude death rate for dialysis patients in 2008 was 12.4% (12.5% for hemodialysis patients and 9.1% for peritoneal dialysis patients), 1.4% for transplanted patients, and 9.4% for all RRT patients. The most common cause of death in dialysis patients was cardiovascular disease (42%), followed by sepsis (14%), malignancy (5%), and cerebrovascular disease (3%). The cause of death in seven kidney graft recipients was: malignancy in three, sepsis in one, pulmonary thromboembolic disease in one, cardiovascular in one, and cerebrovascular in one. The crude death rate of RRT patients from 2004 to 2008, with incident patients at day 1 included, is presented in Table 4.

Table 4. Crude death rate of renal replacement therapy (RRT) patients in the period from 2004–2008 (incident patients at day 1 included)
YearAll RRTAll dialysis (HD + PD)HDPDTx
  • Three kidney graft recipients requiring hemodialysis 2, 14 and 36 days before death were counted as transplant deaths.

  • One kidney graft recipient requiring hemodialysis 42 days before death was counted as a transplant death.

  • §

    § One kidney graft recipient requiring hemodialysis seven days before death was counted as a transplant death. HD, hemodialysis; PD, peritoneal dialysis; Tx, transplant.

2004 12.6%13.1%8.3% 
200510.0%12.8%13.4%6.8%0.9%
200611.4%14.7%15.6%4.6%1.4%
20079.0%11.6%12.3%2.0%1.5%
20089.4%12.4%12.5%9.1%1.4%§

HEMODIALYSIS IN PREVALENT PATIENTS

In 2008, 68.3% (1343/1967) of prevalent RRT patients were treated with chronic hemodialysis (57.5% men; mean age 63.1 ± 14.6 years, median age 66 years, range 9–94), 18.2% were classified as having diabetic nephropathy as the primary renal disease, and 24.3% were reported as having diabetes. The majority of hemodialysis patients (77%) were treated in public, in-hospital dialysis centers, and the minority (23%) in private dialysis centers.

The percentage of patients treated with convective techniques (hemodiafiltration and hemofiltration) is increasing: 17.5% in 2004, 26.9% (N = 339) in 2005, 37.3% (N = 481) in 2006, 40.9% (N = 537) in 2007 and 48% (N = 643) in 2008, of which 611 patients are treated with on-line hemodiafiltration, seven patients with on-line hemofiltration and 25 with acetate-free biofiltration. At the end of 2008, the majority of patients (52%, N = 700) were still treated with bicarbonate hemodialysis. In the majority of hemodialysis patients (74.8%, 1005/1343), ultrapure dialysis fluid was used (including patients treated with convective techniques).

A minority of patients was treated with twice-weekly dialysis (7.4%, N = 99) or once-weekly hemodialysis (0.4%, N = 5), 11 patients (0.8%) with four-times-weekly hemodialysis, and the vast majority, 91.4% (1228/1343), were treated with trice-weekly hemodialysis. The average weekly time on dialysis was 12.9 ± 2.2 h (3–24 h, including patients treated with once- or twice-weekly dialysis), the median weekly time on hemodialysis was 13.5 h. Regular night-shift, in-hospital hemodialysis was offered at the Dialysis Center Zaloška to employed patients, students and pupils. A total of 123 patients (9.2%) were dialyzed using the single-needle dialysis mode.

The mean dry body weight of hemodialysis patients was 69.4 ± 16.0 kg (21–138 kg, median 68 kg). The mean blood flow was 283 ± 51 mL/min (range 120–500 mL/min). Anticoagulation was administered using low molecular weight heparin in 18.2% (N = 244) of hemodialysis patients, while unfractionated heparin was used in the majority (80.5%) of hemodialysis patients. The mean unfractionated heparin dose was 5386 ± 2376 IU per hemodialysis session (median 5000 IU, range 250–18 500 IU).

TRANSMISSIVE DISEASES IN DIALYSIS PATIENTS

Data on transmissive diseases in dialysis patients are collected through dialysis center questionnaires. In 2008, 2.3% (33/1448) of dialysis patients had hepatitis B or C virus infection (two patients had both hepatitis B and C virus infections). The number and percentage of patients with hepatitis has been low over the years. The number of methicillin-resistant Staphylococcus aureus (MRSA)-positive dialysis patients has been decreasing in the last years (0.9% of all prevalent dialysis patients). All positive patients (including MRSA) have been isolated. There were no HIV-positive patients on chronic renal replacement therapy through the end of the year 2008.

ACUTE HEMODIALYSIS

Hemodialysis in intensive care units was performed in 11 hospitals, in 10 of them continuous renal replacement therapy (CRRT) is also performed. CRRT in newborns and small children is performed in the pediatric intensive care unit of the University Medical Center Ljubljana by the nephrologists and renal nurses of the Dialysis Center Zaloška, University Medical Center Ljubljana.

In 2008, 653 patients were treated by acute hemodialysis: 513 (78.6%) patients were treated by intermittent hemodialysis only, 87 (13.3%) by CRRT only, and 53 patients (8.1%) by a combination of CRRT and intermittent hemodialysis.

VASCULAR ACCESS

The vascular accesses in 1343 prevalent chronic hemodialysis patients on 31 December 2008 were: native arteriovenous fistula (AVF) in 82% (N = 1107), PTFE (polytetrafluoroethylene) graft in 6% (N = 74), and catheter in 12% (N = 162). Hemodialysis catheters (N = 162) were: temporary (noncuffed) in 96% and permanent silastic in 3.7% (N = 6) of patients; precurved jugular in 78%, subclavian in 18%, and femoral in 4% of patients; single-lumen in 80% and double-lumen in 20% of patients. Vascular accesses in prevalent dialysis patients from 2005 to 2008 are presented in Figure 1.

Figure 1.

Vascular accesses in prevalent hemodialysis patients in Slovenia from 2005–2008.

On 31 December 2008, there were 224 incident hemodialysis patients who were alive and on hemodialysis at day 91 (patients on PD are excluded), 62% were men, median age was 67.5 years (mean 64.0 ± 15.0, range 16–93 years), 29.5% were diabetic. The vascular accesses (on December 31) were: native AVF in 68% (N = 152), PTFE graft in 3% (N = 6), and catheter in 29% (N = 66) of patients. In patients with AV fistula and graft, the location of fistula/anastomosis was on the forearm in 65%, and on the elbow/arm in 35% of cases. The hemodialysis catheters were: temporary (non-cuffed) in all patients; precurved jugular in 84%, subclavian in 13% and femoral in 3% of patients; single-lumen in 82% and double-lumen in 18% of all cases.

KIDNEY TRANSPLANTATION

The one transplant center in Slovenia, located at the University Medical Center Ljubljana. Slovenia has been a member of Eurotransplant since 1 January 2000 (10,11). Fifty-two kidney transplantations were performed in 2008, all from deceased donors. This was the first graft in 46 patients and the second graft in six patients. Ten transplant recipients were older than 60 years, three transplant recipients were diabetics.

Seven kidney graft recipients died in 2008 with a functioning kidney graft, including one recipient who died seven days after graft failure (dialyzed for seven days). Seven patients started chronic dialysis because of end-stage kidney graft failure.

The total number of renal transplantations in Slovenia from 1970 to 31 December 2008 was 767, of which 125 involved a living related donor and 642 a deceased donor. The total number of patients with functioning kidney grafts (residents only) was 519 on 31 December 2008. Of these patients, 501 (97%) received grafts from deceased and 18 (3%) from living related donors.

CONCLUSION

The incidence rate of end-stage renal disease patients requiring renal replacement therapy patients in the last years in Slovenia has been stable. The number of hemodialysis patients and patients with a functioning kidney graft is increasing, while a decrease in the number of patients treated with peritoneal dialysis has been observed. The majority of dialysis patients are treated in public hospital units. The mortality rate is stable, 9.4% for all renal replacement therapy patients. The longest renal replacement therapy survival is 38 years (with hemodialysis only).

Acknowledgments

This report was supported in part by Grant No. P3-0323-0312 of the Ministry of Education, Science and Technology of the Republic of Slovenia. We would like to thank to Cvetka Likar, a renal nurse, for her dedicated work in collecting data. We would also like to thank the nurses from all renal centers for their help in collecting the data.

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