**4. Discussion**

This is the first report in Colombia to provide an account of the factors affecting HRQOL in patients with mild to moderate renal impairment. It is also the first to point out the advantages that a renal protection program may have over conventional treatment regarding its impact on patient HRQOL. This study's results are presented to comply with the demands that appear in international literature regarding the need to determine the impact on HRQOL in early stages of renal impairment (Chandban et al., 2003; Perlman et al., 2005) and to insist that current interventions must emphasize the preservation of renal functioning in order to decrease the negative impact of kidney failure on HRQOL (Chandban et al., 2003; Fukuhara et al., 2007; Valdebarrano et al., 2001).

Health-Related Quality of Life in Chronic Renal Predialysis

corroborated for each case with the medical staff.

measurements.

Patients Exposed to a Prevention Program – Medellín, 2007-2008 441

Regarding age, patients older than 65 had a lower HRQOL. Physical functioning was the most affected domain for the two groups both at the start of the study and one year later. This could be explained by the strong negative association between the state of physical health and old age. Such association was reported in literature by studies on this and other chronic diseases (Chandban et al., 2005; Hopman et al., 2000; Yepes et al., 2008). The RPP patients younger than 65 showed an increase in four of the domains one year after the start of the study. The rest of the domains also decreased, but not significantly, except for the role-physical domain. For the CT group, all the domains values decreased in the second measurement, and four of them did so significantly. The difference found in physical functioning between the age groups in CT according to the effect size (> 0.60) can be considered to be clinically important. This must be

It is imperative to adjust the differences found in the final HRQOL scores for the variables that can influence such results. As for general health and change in health, upon adjusting for the respective value of the initial score, an increase of more than five points of HRQOL was generated in the difference that favors the RPP over CT in both domains. In the PCS1 and vitality domains, adjusting scores for gender yielded an important increase of the difference in favor of the RPP in both cases (Yepes et al., 2008). In physical functioning, adjusting scores for

In short, exposure to a RPP has a positive impact on the HRQOL of CRF patients from the early stages of their condition. The initial HRQOL score, gender, and age are fundamental characteristics to take into account for measuring the HRQOL of patients upon exposure to an intervention. It seems that early detection of CRF patients and interdisciplinary control of risk factors have a significant influence in the outcome of both physical and mental HRQOL

HRQOL values have been proposed as an important outcome in patients with high death, hospitalization, and depression risks. Measuring the HRQOL with validated instruments such as the SF-36 allows it to become a strong indicator of the health-related quality of life in ambulatory patients. In fact, it is considered a mortality and morbidity predictor in elderly and CRF patients (DeOreo, 1997; Han et al., 2009; Kalantar-Zadeh, 2005; Mapes et al., 2003). Assessing the well-being of CRF patients periodically with the SF-36 is important for measuring response to treatment and for improving healthcare. In fact, improving the

This study's main limitation is its short follow-up period, which could not provide an appropriate account of the characteristics of a slow, progressive disease while explaining that many changes are not significant enough. Another limitation is that demographic variables like marital status, socioeconomic level, occupation, educational level, income, etc., were disregarded. Some studies state that both PCS1 and MCS1 are closely associated with demographic characteristics that are likely to have a deeper impact than clinical

Data loss due to patient death and other causes was expected for the second application of the SF-36 one year later. Like many other health scales, the SF-36 has no clear directions regarding how deaths within a studied population should be analyzed. This has limited the analysis in research. This issue is most frequently addressed by excluding these cases from the study or by analyzing these data separately. Paradoxically, if two study groups are compared, the

age increased the difference in HRQOL scores, favoring CT (Yepes et al., 2008).

HRQOL of CRF patients is a key objective in the U.S (Kalantar-Zadeh, 2005).

characteristics themselves (AASK, 2002; Fukuhara et al., 2007).

The study's data were collected from 293 patients in the early stages of CRF. Patients followed two kinds of medical treatment during one year. The groups showed no differences for the main comorbidities, but it was evident that the RPP collected more patients in earlier stages of CRF due to its active search. The higher proportion of male patients in CT could be due to the faster progression of CRF in males (Silbiger & Neugarten, 1995). This could explain the gender and age disparities found between the groups at the start of the study.

One year later, the RPP group's scores for the different HRQOL domains were slightly lower, but these differences were not significant. Conversely, the CT group showed a significant decrease in four of the eight domains after the same time. This accounts for the effect of the RPP even in a short follow-up period. It is worth noting that general health was the most affected domain in both groups. After one year, the initial value for the RPP remained unchanged, but decreased drastically for CT.

The results obtained from data collected from predialysis patients confirm that HRQOL is affected from the early stages of CRF and continues to decrease as the condition evolves. Even after only one year, the scores for most domains decreased. This conclusion is shared by other studies whose patients lacked RRT. The population assessed in such studies was Japanese (Fukuhara et al., 2007), African-American (African American Study of Kidney Disease and Hypertension Trial Group [AASK], 2002), Australian (Chandban et al., 2005), Korean (Chin et al., 2008), and Dutch (Korevaar et al., 2000).

In this study, the physical health of predialysis patients was found to be more affected than their mental health. This was true for both study groups. These findings are in accordance with the conclusions reached in other publications on the same topic (Chandban et al., 2005; Fukuhara et al., 2007; AASK, 2002; Korevaar et al., 2000; Hopman et al., 2000). Regarding mental health, CT patients initially showed significantly superior values compared to the RPP patients. This result is consistent with the ideas exposed in other studies, which suggest that older patients —or those with an older diagnosis— have better mental health. This proves that mental health is worse in young or recently diagnosed individuals (Hopman et al., 2000). Nevertheless, one year later, the scores for the mental component of HRQOL increased within the RPP group, whereas CT scores decreased, and the initial differences between the RPP and CT disappeared.

Gender was a key factor for the SF-36 scores since its first application. It was observed that the scores for women were lower and had significant differences regardless of the group. However, these differences disappeared within the RPP group one year later. In CT, however, the differences remained and values in men decreased statistically. Other researchers also recognized this affectedness of HRQOL by gender. They also proposed that women may be particularly more vulnerable (Yepes et al., 2008). This was also done in the AASK study (AASK, 2002), which focused on the need for exploring the mechanisms allowing HRQOL in female CRF patients to decrease quickly. In studying the HRQOL of the Australian population suffering from kidney failure Chandban (Chandban et al., 2005) described similar worsening patterns for both genders.

After one year, women's HRQOL in most domains continued to be worse than that of men. However it is worth noting that differences between the values obtained at the start of the study and after one year could be indirectly considered as clinically important in the vitality values for the RPP (ES=0.69) and the bodily pain values for CT (ES=0.61).

The study's data were collected from 293 patients in the early stages of CRF. Patients followed two kinds of medical treatment during one year. The groups showed no differences for the main comorbidities, but it was evident that the RPP collected more patients in earlier stages of CRF due to its active search. The higher proportion of male patients in CT could be due to the faster progression of CRF in males (Silbiger & Neugarten, 1995). This could explain the gender

One year later, the RPP group's scores for the different HRQOL domains were slightly lower, but these differences were not significant. Conversely, the CT group showed a significant decrease in four of the eight domains after the same time. This accounts for the effect of the RPP even in a short follow-up period. It is worth noting that general health was the most affected domain in both groups. After one year, the initial value for the RPP

The results obtained from data collected from predialysis patients confirm that HRQOL is affected from the early stages of CRF and continues to decrease as the condition evolves. Even after only one year, the scores for most domains decreased. This conclusion is shared by other studies whose patients lacked RRT. The population assessed in such studies was Japanese (Fukuhara et al., 2007), African-American (African American Study of Kidney Disease and Hypertension Trial Group [AASK], 2002), Australian (Chandban et al., 2005),

In this study, the physical health of predialysis patients was found to be more affected than their mental health. This was true for both study groups. These findings are in accordance with the conclusions reached in other publications on the same topic (Chandban et al., 2005; Fukuhara et al., 2007; AASK, 2002; Korevaar et al., 2000; Hopman et al., 2000). Regarding mental health, CT patients initially showed significantly superior values compared to the RPP patients. This result is consistent with the ideas exposed in other studies, which suggest that older patients —or those with an older diagnosis— have better mental health. This proves that mental health is worse in young or recently diagnosed individuals (Hopman et al., 2000). Nevertheless, one year later, the scores for the mental component of HRQOL increased within the RPP group, whereas CT scores decreased, and the initial differences

Gender was a key factor for the SF-36 scores since its first application. It was observed that the scores for women were lower and had significant differences regardless of the group. However, these differences disappeared within the RPP group one year later. In CT, however, the differences remained and values in men decreased statistically. Other researchers also recognized this affectedness of HRQOL by gender. They also proposed that women may be particularly more vulnerable (Yepes et al., 2008). This was also done in the AASK study (AASK, 2002), which focused on the need for exploring the mechanisms allowing HRQOL in female CRF patients to decrease quickly. In studying the HRQOL of the Australian population suffering from kidney failure Chandban (Chandban et al., 2005)

After one year, women's HRQOL in most domains continued to be worse than that of men. However it is worth noting that differences between the values obtained at the start of the study and after one year could be indirectly considered as clinically important in the vitality

values for the RPP (ES=0.69) and the bodily pain values for CT (ES=0.61).

and age disparities found between the groups at the start of the study.

remained unchanged, but decreased drastically for CT.

Korean (Chin et al., 2008), and Dutch (Korevaar et al., 2000).

between the RPP and CT disappeared.

described similar worsening patterns for both genders.

Regarding age, patients older than 65 had a lower HRQOL. Physical functioning was the most affected domain for the two groups both at the start of the study and one year later. This could be explained by the strong negative association between the state of physical health and old age. Such association was reported in literature by studies on this and other chronic diseases (Chandban et al., 2005; Hopman et al., 2000; Yepes et al., 2008). The RPP patients younger than 65 showed an increase in four of the domains one year after the start of the study. The rest of the domains also decreased, but not significantly, except for the role-physical domain. For the CT group, all the domains values decreased in the second measurement, and four of them did so significantly. The difference found in physical functioning between the age groups in CT according to the effect size (> 0.60) can be considered to be clinically important. This must be corroborated for each case with the medical staff.

It is imperative to adjust the differences found in the final HRQOL scores for the variables that can influence such results. As for general health and change in health, upon adjusting for the respective value of the initial score, an increase of more than five points of HRQOL was generated in the difference that favors the RPP over CT in both domains. In the PCS1 and vitality domains, adjusting scores for gender yielded an important increase of the difference in favor of the RPP in both cases (Yepes et al., 2008). In physical functioning, adjusting scores for age increased the difference in HRQOL scores, favoring CT (Yepes et al., 2008).

In short, exposure to a RPP has a positive impact on the HRQOL of CRF patients from the early stages of their condition. The initial HRQOL score, gender, and age are fundamental characteristics to take into account for measuring the HRQOL of patients upon exposure to an intervention. It seems that early detection of CRF patients and interdisciplinary control of risk factors have a significant influence in the outcome of both physical and mental HRQOL measurements.

HRQOL values have been proposed as an important outcome in patients with high death, hospitalization, and depression risks. Measuring the HRQOL with validated instruments such as the SF-36 allows it to become a strong indicator of the health-related quality of life in ambulatory patients. In fact, it is considered a mortality and morbidity predictor in elderly and CRF patients (DeOreo, 1997; Han et al., 2009; Kalantar-Zadeh, 2005; Mapes et al., 2003). Assessing the well-being of CRF patients periodically with the SF-36 is important for measuring response to treatment and for improving healthcare. In fact, improving the HRQOL of CRF patients is a key objective in the U.S (Kalantar-Zadeh, 2005).

This study's main limitation is its short follow-up period, which could not provide an appropriate account of the characteristics of a slow, progressive disease while explaining that many changes are not significant enough. Another limitation is that demographic variables like marital status, socioeconomic level, occupation, educational level, income, etc., were disregarded. Some studies state that both PCS1 and MCS1 are closely associated with demographic characteristics that are likely to have a deeper impact than clinical characteristics themselves (AASK, 2002; Fukuhara et al., 2007).

Data loss due to patient death and other causes was expected for the second application of the SF-36 one year later. Like many other health scales, the SF-36 has no clear directions regarding how deaths within a studied population should be analyzed. This has limited the analysis in research. This issue is most frequently addressed by excluding these cases from the study or by analyzing these data separately. Paradoxically, if two study groups are compared, the

Health-Related Quality of Life in Chronic Renal Predialysis

No.13, Sep 1992. p.p 1685-704. EISSN: 1097-0258.

XXIII, No. 6, 2003, p.p 528- 537. ISSN: 0211-6995

No. 3, March 2002, p.p 513-24. EISSN: 1523-6838.

XX, No. 5, Sep 2000, p.p 440-444. ISSN: 0211-6995

Vol. 24, No. 2, Jul-Dec 2006; p.p 37-50. ISSN: 0120-386

Vol. 10, 2009, p.p 39. ISSN: 1471-2369

EISSN 1678-4464

ISSN: 1660-2110

378. EISSN: 1573-2584

8523

17184304

ISSN: 0895-4356

Patients Exposed to a Prevention Program – Medellín, 2007-2008 443

DeOreo PB. (1997). Hemodialysis patient-assessed functinal health status predicts continued

Frison L & Pocock SJ. (1992). Repeated measures in clinical trials: analysis using mean

Fukuhara S, Yamazaki S, Marumo F, Akiba T, Akizawa T & Fujimi T. (2007). The Predialysis

García M, Sánchez M, Liébana A, Pérez V, Pérez P & Viedma G. (2993). Calidad de vida

Han SS, Kim KW, Na KY, Chae DW, Kim YS & Chin HJ. (2009). Quality of life and mortality

Hopman WM, Harrison M B, Coo H, Friedberg E, Buchanan M & VanDenKerkhof EG.

Kalantar–Zadeh K & Unruh M. (2005) Health related quality of life in patients with chronic

Korevaar JC, Jansen MA, Merkus MP, Dekker FW, Boeschoten EW & Krediet RT. (2000)

Kusek, JW; Greene, P; Wang, SR; Beck, G; West, D; Jamerson, K; Agodoa, L; Faulkner, M;

Leanza H, Giacoletto S, Najún C & Barreneche M. (2000) Niveles de hemoglobina y

Leese M, Schene A, Koeter M, Meijer K, Bindman J, Mazzi M, Puschner B, Burti L, Becker

Lugo LH, García HI & Gómez CR. (2006) Confiabilidad del cuestionario de calidad de vida

*Kidney Disease*. Vol. 30, No. 2, Aug, 1997, p.p 204–212. EISSN: 1523-6838. Fleury E, Lana Da Costa C. (2004) Qualidade de vida e saúde: aspectos conceituais e

survival, hospitalization, and dialysis-attendance compliance. *American Journal of* 

metodológicos. *Cadernos de Saúde Pública*. Vol. 20, No. 2, Mar-Abr 2004, p.p 580-588.

summary statistics and its Implications for design. Statistics in Medicine. Vol.11,

CRF Study Group in Japan. Health-Related Quality of Life of Predialysis Patients with Chronic Renal Failure. *Nephron Clinical Practice*. Vol. 105, No.1, 2007, p.p c1-8.

relacionada con la salud en pacientes ancianos en hemodiálisis*. Nefrología*. Vol.

from a nephrologist's view: a prospective observational study. *BMC Nephrology*.

(2000). Associations between chronic disease, age and physical and mental health status. *Chronic Diseases in Canada.* Vol. 29, No. 3, 2000, p.p 108-116. EISSN: 1481-

kidney disease. *International Urology and Nephrology*. Vol. 37, No. 2, 2005, p.p 367–

Quality of life in predialysis end-stage renal disease patients at the initiation of dialysis therapy. *Peritoneal Dialysis International.* Vol. 20, Jan 2000, p.p 69–75. EISSN:

Level, B. (2002). Cross-Sectional Study of Health-Related Quality of Life in African Americans with Chronic Renal Insufficiency: The African American Study of Kidney Disease and Hypertension Trial. *American Journal of Kidney Disease*, Vol. 39,

probabilidad de mejor calidad de vida en hemodializados crónicos. *Nefrología.* Vol.

T, Moreno M, Celani D, White IR & Thonicroft G. (2008). SF-36 scales, and simple sums of scales, were reliable quality-of-life summaries for patients with schizophrenia. *Journal of Clinical Epidemiology.* Vol 61, No. 6, Jun 2008; p.p 588-596.

en salud SF-36 en Medellín, Colombia. *Revista Facultad Nacional de Salud Pública*.

group with more diseased individuals seems to obtain better results. This is because most individuals have died and have been thus excluded from the results and from the analysis.

Due to the negative impact of CRF on HRQOL, it is necessary to determine potential areas for research and clinical intervention. Such areas include: psychological support for the most vulnerable population (women, young people, recently diagnosed patients, patients in early stages of the condition), early prescription of nephroprotectors, and complete physical therapy programs focusing on older patients and on those with high deterioration rates.

#### **5. Acknowledgment**

The authors would like to thank University of Antioquia, Colciencias and Sura EPS for sponsoring this research. We are also very grateful for the patients' cooperation, for the support provided by José Miguel Abad and José Ignacio Acosta, for the advice provided by Professors Rubén Darío Gomez and Juan Luis Londoño, and for Andrés Felipe Quintero Rave's thoughtful translation of this text.

#### **6. References**


group with more diseased individuals seems to obtain better results. This is because most individuals have died and have been thus excluded from the results and from the analysis.

Due to the negative impact of CRF on HRQOL, it is necessary to determine potential areas for research and clinical intervention. Such areas include: psychological support for the most vulnerable population (women, young people, recently diagnosed patients, patients in early stages of the condition), early prescription of nephroprotectors, and complete physical therapy programs focusing on older patients and on those with high deterioration rates.

The authors would like to thank University of Antioquia, Colciencias and Sura EPS for sponsoring this research. We are also very grateful for the patients' cooperation, for the support provided by José Miguel Abad and José Ignacio Acosta, for the advice provided by Professors Rubén Darío Gomez and Juan Luis Londoño, and for Andrés Felipe Quintero

Allison PD. (2001). *Missing data.* Sage University Papers on Quantitative Applications in the Social Sciences, series 07-136. ISBN: 0-7619-1672-5 (p) Thousand Oasks, CA: Sage. Amoedo M, Egea J, Millán I, Gil M, Reig A & Sirvent A. (2004). Evaluación de la calidad de

Atkins RC. (2005). The changing patterns of chronic kidney disease: the need to develop

Cardona D & Agudelo HB. (2005). Construcción cultural del concepto calidad de vida.

Chandban SJ, Briganti EM, Kerr PG, Dunstan DW, Welborn TA, Zimmet PZ & Atkins RC.

Chin HJ, Song YR, Lee JJ, Lee SB, Kim KW, Na KY, Kim S & Chae DW. (2008). Moderately

De Alvaro F, López K & García F. (1997). Salud percibida, estado funcional y mortalidad en

*Transplantation*. Vol. 23, No. 9, 2008, p.p 2810-2817. EISSN: 1460-2385 Cohen J. (1988). The t Test for Means. In: *Statistical Power Analysis for the Behavioral Sciences.* 

from: <http://www.questia.com/PM.qst?a=o&d=98533106>

*Nefrología*. Vol. XVII, No. 4, 1997, p.p 296-303. ISSN: 0211-6995

*International Supplement.* Vol. 98, Sep 2005, p.p 83-85. EISSN: 1523-1755 Cardona D, Estrada A & Agudelo H. (2003). *Envejecer nos toca a todos*. Facultad Nacional de

No. 94, Apr 2005, p.p S14-S18. EISSN: 1523-1755

vida relacionada con la salud mediante láminas COOPWONCA en una población de hemodiálisis. *Nefrología*, Vol. XXIV, No. 5, 2004, p.p 470-479. ISSN: 0211-699 Atkins RC. (2005). The epidemiology of chronic kidney disease. *Kidney International*, Vol. 67,

strategies for prevention relevant to different regions and countries. *Kidney* 

Salud Pública Universidad de Antioquia; 2003. p.p 33 -38, ISBN: 9586557138,

*Revista Facultad Nacional de Salud Pública*. Vol. 23, No. 1, 2005, p.p 79-90. ISSN: 0120-

(2003). Prevalence of kidney damage in Australian adults: the AusDiab Kidney Study. *Journal of the American Society of Nephrology*. Vol. 14, 2003, p.p s131–s138.

decreased renal function negatively affects the health-related quality of life among the elderly Korean population: a population-based study. *Nephrology Dialysis* 

*Second Edition.* Academic Press, p.p 20 – 27, ISBN: 0805802835, New York, retrieved

pacientes diabéticos en tratamiento renal sustitutivo: diseño del estudio Calvidia*.* 

**5. Acknowledgment**

**6. References** 

Rave's thoughtful translation of this text.

Medellín, Colombia.

EISSN: 1533-3450

386


Mapes DL, Lopes AA, Satayathum S, McCullough KP, Goodkin DA, Locatelli F, Fukuhara

Martínez F, Valencia M. (2005) *Modelo de prevención y control de la enfermedad renal crónica.* 

National Kidney Foundation. (2000) K/DOQI Clinical Guidelines for Chronic kidney

<http://www.kidney.org/professionals/kdoqi/guidelines\_ckd/toc.htm> Organización Mundial de la Salud. (2002). Programa de envejecimiento y ciclo vital.

Pérez M, Martín A, Díaz R & Pérez J. (2007}9 Evolución de la calidad de vida relacionada

Perlman R, Finkelstein F, Liu L, Roys E, Kiser M, Eisele G, Burrows-Hudson S, Messana

Rebollo P, Ortega F, Bobes J, Gónzalez M & Saiz P. (2000). Interpretación de los resultados

Rebollo P, Ortega F, Bobes J, Gónzalez M & Saiz P. (2000). Factores asociados a la calidad de

Sanz D, López J, Jofre R, Fort J, Valderrábano F, Moreno F, Vázquez MI & Fort. J (2004).

Silbiger S & Neugarten J. The impact of gender on the progression of chronic renal disease.

Tazeen H. (2006). The growing Burden of Chronic Kidney Disease in Pakistan. *New England Journal of Medicine.* Vol. 354, No. 10, Mar 2006, p.p 995-7. ISSN 1533-4406 Valderrabano F, Jofre R & López JM. (2001). Quality of life in end-stage renal disease

Yepes CE, Montoya M, Orrego BE, Cuellar MH, Yepes JJ, López JP, et al. Calidad de vida en

(TRS). *Nefrología*. Vol. XX, No. 2, Mar 2000, p.p 171-181. ISSN: 0211-6995 Rebollo P, Ortega F, Badía X, Álvarez-Ude F, Baltar J & Álvarez J. (1999). Salud percibida en

XIX, (Supl. 1), 1999, p.p 73-83. ISSN: 0211-6995

29, No. 6, 2009, p.p 548-556. ISSN: 0211-6995

Vol. 64, 2003, p.p 339–349. EISSN: 1523-1755

Vol. 37, No. 2, Aug 2002, p.p 104-105. EISSN: 1578-1747

0734-4, Bogotá.

619-626. ISSN: 0211-6995

EISSN: 1523-6838.

0211-6995

ISSN: 0211-6995

464. EISSN: 1523-6838.

1523-6838.

S, Young EW, Kurokawa K, Saito A, Bommer J, Wolfe RA, Held PJ & Port FK. (2003). Health-related quality of life as a predictor of mortality and hospitalization: the Dialysis Outcomes and Practice Patterns Study (DOPPS). *Kidney International*.

*Componente de un modelo de Salud Renal*. Fedesalud, p.p 17-55, ISBN: 978-958-44-

disease. In: N*ational Kidney Foundation*. Access in July, 2007. Available from:

Envejecimiento activo: un marco político. *Revista española de geriatría y gerontología*.

con la salud en los trasplantados renales. *Nefrología.* Vol. XXVII, No. 5, 2007, p.p

JM, Levin N, Rajagopalan S, Port FK, Wolfe RA & Saran R. (2005). Quality of Life in Chronic Kidney Disease (CKD): A Cross-Sectional Analysis in the Renal Research Institute. *American Journal of Kidney Disease*. Vol. 45, No. 4, Apr 2005, p.p 658-666.

de la calidad de vida relacionada con la salud en terapia sustitutiva de la insuficiencia renal terminal. *Nefrología.* Vol. XX, No. 5, Sep 2000, p.p 431-439. ISSN:

vida relacionada con la salud (CVRS) de los pacientes en terapia renal sustitutiva

pacientes mayores de 65 años en tratamiento sustitutivo renal (TSR). *Nefrología.* Vol.

Diferencias en la calidad de vida relacionada con la salud entre hombres y mujeres en tratamiento con hemodiálisis. *Nefrología.* Vol. XXIV, No. 2, 2004, p.p 167-178.

*American Journal of Kidney Disease.* Vol. 25, No. 4, Apr 1995; p.p 515-533. EISSN:

patients. *American Journal of Kidney Disease*. Vol. 38, No. 3, Sep 2001, p.p 443-

pacientes con enfermedad renal crónica sin diálisis ni trasplante de una muestra aleatoria de dos aseguradoras en salud. Medellín, Colombia, 2008. *Nefrología*. Vol.
