Epidemiologic aspects of dialysis therapy in the Great São Paulo

Epidemiologic aspects of dialysis therapy in the Great São Paulo
R. SESSO, M.S. ANÇÃO, S.A. MADEIRA, REGIONAL COMMISSION OF NEPHROLOGY OF THE SECRETARY OF HEALTH OF THE STATE OF SÃO PAULO AND HEALTH INFORMATICS CENTER OF ESCOLA PAULISTA DE MEDICINA*
Secretary of Health of the State of São Paulo and Escola Paulista de Medicina, São Paulo, SP. *The members from the Regional Commission of Nephrology and the Health Informatics Center of Escola Paulista de Medicina are shown in the appendix.

SUMMARY
Objective. Epidemiological data about the treatment of patients with end-stage renal disease in the Great São Paulo, Brazil, are presented.
Material and Methods. Patient on dialysis in the city of São Paulo and surroundings, distributed in 15 Regional Offices of Health (ERSAs), during 1991, were studied. Data were collected by the Secretary of Health of the State of São Paulo.
Results.There was an increase of 18.6% in the number of alive patients on dialysis from January 1st to December 31 (n = 2,425 to 2,875). The patients were distributed in 40 dialysis centers, of which 25 were just located in the ERSAs 1, 2 and 3. Depending on the ERSA, a variable percent from 37% to 88% did not live in the same treatment area. At the end of the year, 79% of the patients were on hemodialysis, 15% on continuous ambulatory peritoneal dialysis and 6% on intermittent peritoneal dialysis. The diagnoses more frequently reported of primary disease were uncertain, glomerulonephritis, hypertension and

diabetes (36%, 27%, 17% and 8%, respectively). New cases (1.483) began dialysis during the year, corresponding to an incidence rate of 83 patients per million population (pmp). The prevalence of patients on dialysis was 148 pmp. The global annual.fatality rate was 17.2% (range in the ERSAS: 12.0 - 3.5). The actuarial one year survival .for the patients who started treatment in 1991 was 80.2%. 246 patients received kidney transplant, corresponding to 14 patients pmp.
Conclusions.Dialysis treatment provided in the Great São Paulo is satisfactory. There are inequalities related to the assistance in different ERSAS, which may reflect the distribution of tertiary referral centers in the region.
[Rev Ass Med Brasil 1994; 40(1): 10-4]

KEY WORDS: End-stage renal disease. Chronic renal failure. Dialysis. Epidemiology

INTRODUCTION
In Brazil it is esteemed that there are now about 20.000 patient in treatment for end-stage renal disease (ESRD). São Paulo is the State of the Federation that contributes with the largest percent of these patients. Dialysis is a long term procedure and with high cost. The National Institute of Social Welfare (INPS) has been providing resources for the dialytic therapy since 1974.
In São Paulo as in the great part of the country, official and precise data on epidemiologic aspects and health care of the dialysis therapy have been practically nonexistent in the last 19 years. For the best utilization of the limited available economic resources in the health care area and in particular for the treatment of ESRD, it is the utmost importance the knowledge of more precise data to that respect. Such information will be significant to address important subjects, as much in the renal community, as in the area of planning of health care, referring to the aetiology, prevention of ESRD, access to the services, mortality, morbidity, quality control of the delivered dialysis therapy, forecast of staff costs in the area, etc.
We present, in this report, data collected by the Secretary of Health of the State of São Paulo on the dialysis treatment of ESRD patients during the year of 1991 in the city of São Paulo and surroundings.

MATERIAL AND METHODS
Administratively, Great São Paulo (Macro-region 1 of the State) it is composed of 15 Regional Offices of Health (ERSAs or SUDS), according to location schematized in the fig.1. ERSAs from 1 to 8 constitutes the city of São Paulo, corresponding to the following areas: 1 - Center, 2 - Butantã, 3 - Vila Prudente, 4 - Penha, 5 - ltaquera, 6 - Mandaqui, 7 - Nossa Senhora do Ó and 8 - Santo Amaro, the others are the following ones: 9 - Santo André, 10 - Mauá, 11 - Osasco, 12 - ltapecerica, 13 - Mogí das Cruzes, 14 - Franco da Rocha and 15 - Guarulhos.

Fig.1 - Outline of the distribution of the Regional Offices of Health (ERSAS) in Great São Paulo. 1 - Center, 2 - Butantã, 3 - Vila Prudente, 4 - Penha, 5 - ltaquera, 6 - Mandaqui, 7 - Nossa Senhora do Ó, 8 - Santo Amaro, 9 - Santo André, 10 - Mauá, 11 - Osasco, 12 - ltapecerica, 13 - Mogí das Cruzes, 14 - Franco da Rocha and 15 - Guarulhos.

The staff of dialysis centers fill monthly, several forms and sent them to the respective ERSA and also to the Regional Commission of Nephrology of the State. These forms are part of the Procedures Guide of Nephrology, made by the Regional Commission of Nephrology and that follows the normatization that disciplines the dialysis therapy in Brazil (OS/INAMPS/DCASS nº 170, 6/19/89). We used, in this study. information contained in the forms 2 and 4 of the guide with information about identification, demographic data, diagnosis of the primary renal disease, treatment type, treatment alterations, death, etc.
We included in this study all the alive patients on dialysis therapy at 1/1/91 and the ones that began treatment during the year of 1991 up to December 31. The data were collected, prospectively, by the Regional Commission of Nephrology, through a microcomputer-based system and a relational database developed by the Health Informatics Center of the Escola Paulista de Medicina.
Referring data to the number of inhabitants at July 1st of 1991, in each ERSA, were estimated, and the referring ones to the population of Great São Paulo are in agreement with the state census and they were supplied by the Secretary of Health of the State.
In the analysis of the data we used the following epidemiologic concepts: rate of incidence of dialytic treatment: number of new patients beginning dialytic treatment during 199l / population at risk at the middle of the year; rate incidence of transplants: number of patients transplanted during the year / population in dialysis at the middle of the year; prevalence rate: number of patients alive in dialysis at July 1st of 91 / total population in the same period; fatality rate: number of deaths for ESRD during the year / number of cases of ESRD during the year. Cumulative survival was obtained by the actuarial method.

RESULTS

The table 1 shows the characteristics of the patients that undergoing dialysis treatment at December 1991. Most of them (41%) had among 40-59 years old; we could observe a high percentage (25%) of patients with more than 60 years. A few more than the half (56%) were males. The diagnosis most frequently reported as primary renal disease were: uncertain, chronic glomerulonephritis and hypertension. Eight percent were diabetics.

Table 1 - The characteristics of patients in dialysis at December,1991
	N	%
Age group
0 - 19	94	3.2
20 - 39	917	31.2
40 - 59	1.181	40.7
> 60	713	24.5
Gender
Male	1.633	56.2
Female	1.272	43.8
Primary Renal Disease
Uncertain	1.053	36.2
Chronic glomerulonephritis	799	27.5
Hypertension	489	16.8
Diabetes	232	8.0
Tubulo-insterstitial nephropaty	115	4.0
Policystic nephropaty	87	3.0
Lupus nephropaty	37	1.3
Others	133	4.6
No answer	75	2.6
Calculations computed for 2.905 patients in dialysis.

In Great São Paulo there was a total of 40 centers of dialysis at the end of 1991 (2,2 centers per million population [pmp]) (table 2). Sixty percent of the centers are located in ERSAs 1, 2 and 3, being just 40% of them in ERSA 1. There are 4 ERSAs (7, 10, 12, 14) without dialysis facilities. The number of patients in dialysis at the beginning and at the end of 1991, in several ERSAS it is shown in the table 2. ERSAs 1 and 3 are the ones that presents the larger number of patients receiving treatment. There was an increase of 18.6% (n = 450) in the number of patients at the end of the year. The patients' distribution in relation to the type of dialytic treatment went for hemodialysis, continuous ambulatorial peritoneal dialysis and intermittent peritoneal dialysis respectively, 79% (n = 2.272), 15.1% (n = 433) and 5.9% (n = 170). A proportion relatively larger of patients with more than 60 years and of diabetics were in peritoneal dialysis (30.4% and 41.4%, respectively).

Table 2 - Number of dialysis centers, number of patients in dialysis and general population of the area, according to the Regional Office of Health (ERSA), in 1991.
Number of patients
ERSA	Number of centers	01/01/91	12/ 31/91	Population (x 1000)*
1	16	956	1.064	1.250
2	5	201	217	896
3	4	285	403	1.374
4	2	151	158	1.101
5	2	208	240	1.923
6	2	130	152	1.043
7	0	0	0	1.062
8	2	152	153	2.169
9	4	202	256	1.918
10	0	0	0	423
11	1	62	109	1.266
12	0	0	0	523
13	1	14	51	719
14	0	0	0	237
15	1	64	72	915
Total	40	2.425	2.875	17.853
The general population of each Regional Office of Health was esteemed, the total population was obtained according with the state census. Data supplied by Secretary of Health of the State.

Several admission characteristics and exit of dialysis program including center transfer, recovery of renal function, transplant and death, by ERSA, is presented in the table 3. The number of new cases that began dialytic treatment in 1991 was 1.483 (difference among the admitted cases and transferred of center). Therefore, the annual incidence of new cases in dialysis in the general population was 83 per million. That is to say, a new patient began dialysis in each 12.000 inhabitants. The global prevalence of dialysis therapy was 148 patients pmp (a patient for 7.000 inhabitants). There was great variation of this rate among several ERSAs (46-807). These estimates don't take into account that many patients make dialysis in centers located in an ERSA different from the area in which they live. In fact, most of the dialysed patients at centers of ERSA 1 and 3 don't live in same ERSA; contrasting with the observed for patients in treatment at ERSA 5 and 9, such percentages were 88%, 87%, 37% and 38% respectively.

Table 3 - Number of patients according with the entrance and the exit of dialytic treatment by Regional Office of Health (ERSA) *, during 1991.
ERSA	Admited	Transferred of center	Lost / abandonment	Recovered function	Transplanted	Died
1	647	142	33	12	126	226
2	16	27	3	7	20	53
3	366	119	11	1	46	71
4	77	14	2	4	16	34
5	162	46	7	12	11	54
6	58	11	2	0	2	21
8	149	42	7	12	9	78
9	220	37	12	12	10	95
11**	49	2	-	-	-	-
13**	39	2	-	-	-	-
15	37	5	17	1	6	17
Total	1.930	447	77	61	246	649
Excluded ERSAs without dialysis centers (7, 10, 12, 14). *Insufficient patients' follow-up.

Seventeen out of 100 patients undergoing dialytic treatment died during the year (table 4). This rate already includes in its denominator the patients in follow-up on January of 91, plus the new cases admitted during the year. Most of ERSAs presented a fatality rate between 12% and 18% by year, except ERSAs 8 and 9 with rates of 33% and 26%, respectively. The actuarial survival rate of patients just admitted in 1991 was of 80.2% at the end of the first year (fig. 2). The annual rate of mortality for patients with ESRD on dialysis was of 36.4 pmp. On the average, 9 out of 100 patients on dialysis received a kidney transplant during 1991 (variation 1.4 -13.4 in several ERSAS). Most of the transplants were accomplished in patients of ERSAs 1, 2, 3 and 4 (half of these patients were just on dialysis at ERSA1). The annual incidence of kidney transplant was of 13.8 pmp.

Table 4 - Prevalence of dialytic treatment, annual rate of fatality, annual incidence of transplants in the population on dialysis, according with the Regional Office of Health (ERSA), during 1991.
ERSA	Prevalence (pmp)	Annual fatality rate (%)	Incidence of transplant (%)
1	807	16.0	12.5
2	233	18.3	9.6
3	250	13.7	13.4
4	141	16.3	10.3
5	116	17.7	4.9
6	135	12.0	1.4
8	71	32.5	5.9
9	119	26.3	4.4
11*	68	-	-
13*	46	-	-
15	74	17.9	8.8
Total	148	17.2	9.3
*Insufficient data. pmp = per million population

Fig.2 - Actuarial survival curve from patients that began dialysis therapy in the Great São Paulo in 1991, N = 1.483

DISCUSSION

This study provides objective and important information about the dialytic treatment in patients from the Great São Paulo.
We observed a considerable annual increase of 18.6% in the population on dialysis in 1991. An expressive proportion (25%) of these patient has more than 60 years. In fact, in the USA, about 40% of the new patients on dialysis therapy have more than 65 years old. The annual rate of acceptance of new patients for dialysis treatment, 83 pmp, it is superior to the incidence rate observed in Europe in 1991 (48 pat. pmp) and inferior to referred her in the USA in 1988 (147 pat. pmp). The number of patients alive on dialysis, at July of 1991 (148 pmp), it is close to the reported by EDTA (170 pat. pmp), although it is about 1/3 of the North American prevalence (441 pat. pmp). Our transplant activity in 1991 (14 pat. pmp) it is also close of the global European (17 pat. pmp).
The percentage of patients in peritoneal dialysis (21%) it is superior to the referred in EDTA (13%) and in the USA (11.4%). In particular, we observed that the older patients (30%) and the diabetics (41%) are more frequently treated by peritoneal dialysis when compared to those more youths or with other diagnoses of primary renal diseases. It is remarkable that diabetes is just the third cause more commonly reported of primary renal disease in patients on dialysis. This data contrasts with the observed in the USA, where the diabetes is the first cause, responsible for almost 30% of the new cases in treatment for ESRD. Although it is evident the rough precision of the diagnosis reported of primary renal disease, it is improbable that there is a great mistake in the diagnosis of diabetes, mainly owing to its clinical manifestations.
The annual mortality rate for dialysis therapy was of 17.2%. This calls the attention for the variation of these rates between the ERSAs, reaching up to 30% in two of them. However, this rate doesn't allow correction for the different duration in the follow-up of the patients and it includes old cases in dialysis in 1/1/91. So, it is preferred to use the probability of actuarial survival, this methodology resulted in a survival rate of 80% at the end of the first year of the beginning of the dialysis. This rate is comparable with to the international one and it seems reasonable when we take into account the comorbidity factors, the several primary renal diseases and the patients' age groups in the studied population.
The attempt of study the prevalence and incidence rates of ESRD by ERSA, although valid, has limitations in its analysis, once the location of the dialysis centers reflects the distribution of the big hospitals in São Paulo. It is known that these hospitals are located in ERSAs 1, 2 and 3. In this evidence line. we observed that a variable percent of 37% to 88% of the patients accomplish treatment in ERSA different from that where they resides. indicating a sharp tendency to be dialysed in units of central areas of the Capital.
Incidence and prevalence rates of patients in dialysis, cumulative survival and transplanted rates, besides other morbidity indexes, constitute objective and important indicators of the quality of the treatment supplied for the ESRD, so much in local level as in a more global analysis for planning health care. These preliminary indexes indicate that, in a general way, the rendered attendance the patients with ESRD in Great São Paulo is satisfactory. There is, however, evident disproportions in relation to attendance rendered in several ERSAs and that should reflect the problem of the distribution of hospitals of tertiary attendance in Great São Paulo.

APPENDIX

Members of the Regional Commission of Nephrology: Sérgio A. Madeira, Ricardo Sesso, José A. Lima, Antonio M. Lucon, Célio P. Lima, Luís A. Lucarelli, Thiers A. Nazareth, Yara T.P. da Silva, Antonia G. Silva, Renata Takaoka, lone T.P. Costa and Suely B. C. Rezende.
Members of the Health Informatics Center of the Escola Paulista de Medicina: Meide Anção, Sérgio Draibe, Daniel Sigulem, Marlene Sakumoto and Luís A. Pereira.

BIBLIOGRAPHICAL REFERENCES

1.Procedures Guide in Nephrology. Regional Commission of Nephrology, Gepro/Cadais, Secretary of Health, São Paulo, August, 1989.
2. Daniel WW. Biostatistics: a Foundation for Analysis in the Health Sciences. 5th ed, New York, John Wiley & Sons, 1991.
3. US Renal Data System.USRDS 1990 Annual Data Report, TheNational Institutes of Health, National Institute of Diabetes and Digestive and Kidney Disease, Bethesda, MD, August 1990.
4. Raine AEG, Margreiter R, Brunner FP et al. Report on the management of renal failure in Europe, XXII, 1991. Nephrol Dial Transplant 1992; Suppl. 2:7-35.

Comments and suggestions: Meide S. Anção, M.D.

Epidemiologic aspects of dialysis therapy in the Great São Paulo

Table 1 - The characteristics of patients in dialysis at December,1991

Table 2 - Number of dialysis centers, number of patients in dialysis and general population of the area, according to the Regional Office of Health (ERSA), in 1991.

Table 3 - Number of patients according with the entrance and the exit of dialytic treatment by Regional Office of Health (ERSA) *, during 1991.

Table 4 - Prevalence of dialytic treatment, annual rate of fatality, annual incidence of transplants in the population on dialysis, according with the Regional Office of Health (ERSA), during 1991.