Nephrology 15 (2010) 3–9
Review Article
Epidemiology, impact and preventive care of chronic kidney disease in Taiwan nep_
3..9
SHANG-JYH HWANG, JER-CHIA TSAI and HUNG-CHUN CHEN Department of Medicine, Division of Nephrology, Kaohsiung Medical University Hospital, Faculty of Renal Care, Kaohsiung Medical University, College of Medicine, Kaohsiung, Taiwan
KEY WORDS: chronic kidney disease, epidemiology, preventive care. Correspondence: Professor Hung-Chun Chen, Department of Medicine, Division of Nephrology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, 100 Tz-You 1st Road, Kaohsiung 807, Taiwan. Email:
[email protected] Accepted for publication 25 February 2010. doi:10.1111/j.1440-1797.2010.01304.x
ABSTRACT: Chronic kidney disease (CKD) has emerged as a global public health burden. Taiwan has the highest incidence and prevalence rates of endstage renal disease (ESRD) in the world. In this review, the following key issues of CKD in Taiwan are addressed: epidemiological data, underlying diseases patterns, risk factors, public health concerns and a preventive project. Prevalence of CKD are reported to be 6.9% for CKD stage 3–5, 9.83% for clinically recognized CKD and 11.9% for CKD stage 1–5. However, overall awareness of CKD is low, 9.7% for CKD stage 1–3 and 3.5% for stage 1–5. Diabetes mellitus (43.2%), chronic glomerulonephritis (25.1%), hypertension (8.3%) and chronic interstitial nephritis (2.8%) are four major underlying renal diseases of ESRD. Older age, diabetes, hypertension, smoking, obesity, regular use of herbal medicine, family members (both relatives and spouses), chronic lead exposure and hepatitis C are associated with higher risk for CKD. Impact of CKD increases risk of allcause mortality and cardiovascular diseases, especially in those with overt proteinuria and advanced CKD stages. These impacts lead to increased medical costs. The nationwide CKD Preventive Project with multidisciplinary care program has proved its effectiveness in decreasing dialysis incidence, mortality and medical costs. It is crucially significant from Taiwan experience on CKD survey and preliminary outcome of the preventive project. Provision of a more comprehensive public health strategy and better care plan for CKD should be achieved by future international collaborative efforts and research.
Chronic kidney disease (CKD) has emerged as a global public health burden for its increasing number of patients, high risk of progression to end-stage renal disease (ESRD), and poor prognosis of morbidity and mortality.1,2 It attracts worldwide attention to its epidemiology, risk factors, treatment plans and preventive actions.3 Estimated glomerular filtration rate (eGFR) has become a standard method to evaluate CKD based on diagnostic criteria and classification by the National Kidney Foundation, USA.4 However, the reported prevalence of CKD has varied among different countries because of the discrepancies in age, ethnic groups, survey policies and equations of eGFR calculation.5–10 The patterns of associated risk factors and targeting strategies are also quite diverse. Taiwan has the highest incidence and prevalence rates of ESRD in the world according to the United States Renal Data © 2010 The Authors Journal compilation © 2010 Asian Pacific Society of Nephrology
System (USRDS) Annual Data Report.11 Thus, it is worthwhile to make explicit the epidemiology, risk factors, impact and preventive strategies for CKD in Taiwan. We hope that this approach may provide valuable lessons and experiences to many countries that are suffering from serious CKD problems and are making efforts to tackle them. In this review, we aim to address the following key issues of CKD focusing on Taiwan: epidemiological data, underlying diseases patterns, risk factors, public health concerns and a preventive project.
EPIDEMIOLOGY OF CKD IN TAIWAN: A WORLDWIDE COMPARISON A nationwide, randomized, stratified survey for hypertension, hyperglycaemia and hyperlipidaemia (TW3H) by Hsu
3
S-J Hwang et al.
et al. reported a prevalence rate of 6.9% of CKD stage 3–5 in the subjects over 20 years-old (n = 6001).8 The second wave follow-up study of TW3H Survey revealed 9.8% of CKD stage 1–5 (n = 5943) adjusted by age of the population in 2007 (unpubl. data, 2009). Another survey from the dataset of National Health Insurance (NHI) using disease code analysis by Kou et al. reported the prevalence of clinically recognized CKD as 9.83% and the overall incidence rate during 1997– 2003 as 1.35/100 person-years.12 A large database of 13-year cohort commercial health examination by Wen et al.13 later reported an overall prevalence of 11.9% of CKD stage 1–5 (n = 462 293). The prevalence of each stage of CKD (I–V) was 1.0% (I), 3.8% (II), 6.8% (III), 0.2% (IV) and 0.1% (V). Despite the differences in data sources, study subjects and definition of CKD, the prevalence of CKD (9.8–11.9%) in Taiwan was slightly lower than 13.1% in United States, National Health and Nutrition Examination Survey (NHANES III, 1999–2004).6 The underestimated prevalence of CKD in Taiwan might be explained by variation in sampling methods and eGFR calculation system. Further worldwide epidemiological comparison on the prevalence of CKD is listed in Table 1. In Europe, the population-based Health Survey of Nord-Trondelag County (HUNT II), using the same methods as NHANES, reported a 10.2% prevalence of CKD in Norway.7 In the Asia–Pacific area, based on different published reports, the prevalence of CKD stage 3–5 or total CKD was approximately 12.9–15.1% in Japan, 3.2–11.3% in China, 7.2–13.7% in Korea, 8.45– 16.3% in Thailand, 3.2–18.6% in Singapore, 4.2% in India and 11.2% in Australia.
AWARENESS OF CKD A low awareness rate in contrast to high prevalence of CKD is a serious public health problem in Taiwan. Hsu et al. 8 reported an overall awareness rate of CKD of 9.7% in contrast to 6.9% prevalence rate for CKD stage 3–5. Awareness rates for each stage of CKD were 8.0% (stage 3), 25.0% (stage 4) and 71.4% (stage 5). In Wen’s report,13 the overall awareness of CKD stage 1–5 was only 3.5%. Awareness rates for each stage of CKD are 2.66% (stage 1), 2.68% (stage 2), 4.10% (stage 3), 23.67% (stage 4) and 52.40% (stage 5). Notably, low awareness in contrast to high prevalence of CKD is especially more common in subjects of low socioeconomic and educational status. This fact raises the importance of promoting awareness of CKD through patient education and an intensive screening program. For example, World Kidney Day and a public media campaign have been implemented in Taiwan since 2007. More importantly, continuing medical education is crucially needed for each level of medical physician in all specialties. We must foster the health-care professionals to learn the new concept of CKD definition and classification4 and to provide the rational care for this rapidly growing population of CKD.
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HIGH INCIDENCE AND PREVALENCE OF ESRD IN TAIWAN: CURRENT STATUS AND WHY Taiwan has the highest incidence and prevalence rate of ESRD based on international comparisons of the USRDS report.11 Based on the National Dialysis Registry by the Taiwan Society of Nephrology (TSN), Yang et al. reported that from 1990 to 2001 incidence and prevalence rates of ESRD patients increased 2.6 times from 126 to 331/million populations (pmp) and 3.46 times from 382 to 1322/pmp, respectively, from 1990 to 2001.27 Recent data from the Dialysis Registration of the TSN in 2007 reported 48 072 haemodialysis (HD) and 4465 peritoneal cases, corresponding to a prevalence of 2288/pmp and incidence of 415/pmp, respectively.11 The heavy burden of renal replacement therapy by dialysis was managed by a total of 1081 board-certificated nephrologists, 534 dialysis centres and 14 502 HD machines. Moreover, the domestic renal transplant patients from 1997–2007 were 2054 cases based on the data of the Bureau of National Health Insurance (BNHI). However, it was estimated that another 50% of patients received off-shore renal transplantation, mainly from China. There are several possible explanations for the high incidence and prevalence of ESRD in Taiwan. First, a major reason is that the launching of the NHI in 1995 provided free coverage for dialysis therapy without co-payment.28 The universal coverage facilitates the utilizations of renal replacement therapy and further accelerates the inflow of dialysis patients. Second, the better health-care system may improve the survival rate of chronic diseases patients and increase the overall life expectancy. This reason is supported by the evidence that the increased ESRD population consisted of mainly elderly (>65 years) and diabetic patients in Taiwan.27 Elderly cases constitute approximately half of the incidence of dialysis cases and diabetic cases constitute approximately 40% of the incidence of dialysis cases. Third, low transplantation rate and low mortality rate in dialysis patients further retains the numbers of the dialysis patient pool.29
PRIMARY RENAL DISEASES OF ESRD Diabetes mellitus (DM) (43.2%), chronic glomerulonephritis (CGN) (25.1%), hypertension (8.3%) and chronic interstitial nephritis (2.8%) are four major underlying renal diseases of ESRD in 2007. DM has become the first leading cause of ESRD by outnumbering CGN since 2000.28 Unknown causes of ESRD are especially often reported as CGN. It implies that a significant portion of patients with hypertension and chronic interstitial nephritis might be underestimated as the underlying causes of ESRD. It needs more in-depth investigation to identify the exact pattern of primary diseases of ESRD. © 2010 The Authors Journal compilation © 2010 Asian Pacific Society of Nephrology
Epidemiology of CKD in Taiwan
Table 1 Epidemiology of CKD in Asian and Western countries Countries/authors
Study design
Samples size/period
Taiwan Wen et al.13
CS
n = 462 293 year: 1994–2006
Four-variable MDRD†
Hsu et al.8
CS
Four-variable MDRD†
Kuo et al.12
CS
n = 5 409 year: 2002 n = 176 365 year: 1997–2003
Total CKD: 11.9% Stage 1: 1.0% Stage 2: 3.8% Stage 3: 6.8% Stage 4: 0.2% Stage 5: 0.1% Stage 3–5: 6.9%
ICD-9 codes‡
Total CKD: 9.83% in 2003
Japan Imai et al.9
CS
n = 527 594 year: 2000–2004
Japanese four-variable MDRD§
Iseki et al.14
CS
n = 154 019 year: 2003
Four-variable MDRD†
Total CKD: 12.9% Stage 1: 0.6% Stage 2: 1.7% Stage 3: 10.4% Stage 4+5: 0.2% eGFR
