RENAL DATA FROM THE ARAB WORLD
|Year : 2015 | Volume
| Issue : 5 | Page : 1028-1034
|Epidemiology and referral patterns of patients with chronic kidney disease in the Emirate of Abu Dhabi
Nick Richards1, Mohamed Hassan2, Abdul Karim Saleh2, Hormazdiar Dastoor3, Bassam Bernieh4, Samra Abouchacra4, Omar Al Jabri5, Alan Fleischmann5, Marie Richards1, Daniele Marcelli6
1 Head Office, SEHA Dialysis Service, Abu Dhabi, United Arab Emirates
2 Department of Nephrology, Sheikh Khalifa Medical City, Abu Dhabi, United Arab Emirates
3 Department of Nephrology, Al Mafraq Hospital, Al Mafraq, Abu Dhabi, United Arab Emirates
4 Department of Nephrology, Tawam Hospital, Al Ain, Abu Dhabi, United Arab Emirates
5 Medical Director's Office, Ambulatory Health Services, Abu Dhabi, United Arab Emirates
6 Medical Board, Fresenius Medical Care, Bad Homburg, Germany
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|Date of Web Publication||7-Sep-2015|
| Abstract|| |
According to estimates, the dialysis prevalence in Abu Dhabi is around 370 per million population. The annual growth is 12-15% and the dialysis population is likely to double in the next five years. Most patients present to dialysis as an emergency and only 2.7% have an arteriovenous fistula at the first dialysis. The prevalence of chronic kidney disease (CKD) in the Emirate is undefined. A study of the epidemiology of CKD and referral patterns was undertaken. SEHA, the Abu Dhabi Health Service delivery company, has a unified computer system containing all measurements made in its laboratories. This study considered all serum creatinine measurements performed between 1 September 2011 and 31 October 2012 from outpatient departments or emergency rooms. The estimated glomerular filtration rate (eGRF) was calculated using the Modification of Diet in Renal Disease formula (the Schwartz formula was used for children). We identified 331,360 samples from 212,314 individuals. The mean serum creatinine was 61 ± 48 μmol/L in females (59 ± 43 μmol/L in Emiratis, 63 ± 54 μmol/L in expatriates) and 87 ± 69 μmol/L in males (80 ± 59 μmol/L in Emiratis, 92 ± 74 μmol/L in expatriates). Among Emiratis, 4.6% of males and 2.8% of females had an eGFR between CKD 3 and 5. Among expatriates, 4.2% of males and 3.2% of females had an eGFR between CKD 3 and 5. On average, eight months elapsed before a patient with CKD 3, and three months for a patient in CKD 5, to attend the nephrology clinic. This study has defined the prevalence of CKD within Abu Dhabi and demonstrated the need to improve identification and referral of CKD patients. Possible solutions include campaigns to increase public and physician awareness of CKD.
|How to cite this article:|
Richards N, Hassan M, Saleh AK, Dastoor H, Bernieh B, Abouchacra S, Jabri OA, Fleischmann A, Richards M, Marcelli D. Epidemiology and referral patterns of patients with chronic kidney disease in the Emirate of Abu Dhabi. Saudi J Kidney Dis Transpl 2015;26:1028-34
|How to cite this URL:|
Richards N, Hassan M, Saleh AK, Dastoor H, Bernieh B, Abouchacra S, Jabri OA, Fleischmann A, Richards M, Marcelli D. Epidemiology and referral patterns of patients with chronic kidney disease in the Emirate of Abu Dhabi. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2020 May 29];26:1028-34. Available from: http://www.sjkdt.org/text.asp?2015/26/5/1028/164600
| Introduction|| |
Abu Dhabi is the largest emirate of the United Arab Emirates (UAE), and, according to the mid-2012 census, the population is 2,334,563, around a 10-fold increase on that estimated in the 1975 census. The population increased substantially due to a combination of the high birth rate and high net migration of expatriate workers of different nationalities.  The age structure of the population is quite young, with only 0.9% of people being >65 years old, whereas the equivalent figure in the European Union is approximately 17.5% according to Eurostat (2011). Worldwide, the growing burden of chronic kidney disease (CKD) has been attributed to the aging of the population and the increasing prevalence of obesity and consequently of type-2 diabetes. In the area of the Gulf, the neighboring Saudi Center for Organ Transplantation reported an 8% annual increase in the incidence rate of end-stage renal disease (ESRD) patients,  much higher than expected in view of the population age structure. Also, in Abu Dhabi, the impact of aging cannot be considered a factor, but clearly the rapid socio-economic development in the last decades has resulted in changes in lifestyle and nutritional habits. In 2007, Malik et al  reported that 21.5% of children aged 5-17 years were overweight and 13.7% were obese, asking for prompt actions to initiate preventative and interventionist strategies to reverse the trend of what they call an emerging epidemic. Therefore, it is not surprising to find that the prevalence of diabetes is 10% and that once the prevalence is adjusted with the age profile of the world population it increases to 19%, ranking globally among the top countries for prevalence of diabetes. In addition, 12.5% of the population has impaired glucose tolerance, increasing to 16.6%, once age-adjusted. 
Data on the burden of CKD in the Emirates, and more generally in the Arabian Peninsula, remains poor. According to the estimation of the SEHA Dialysis Services, the Abu Dhabi agency responsible for delivering renal replacement therapy, the current prevalence of patients on dialysis is around 370 per million population (pmp). The annual growth of the dialysis population is an impressive double digit (12-15%), and, accordingly, the population of patients on dialysis will double in the next five years. Most new patients present to dialysis as an emergency, with only 2.7% having an arteriovenous (AV) fistula at the time of first dialysis. Late presentation means greater acidosis, hypo-calcemia, hyperphosphatemia and anemia, and less wellcontrolled hypertension and fluid overload, than in patients presenting earlier.  Late presentation is multifactorial, with disease denial and nonattendance after referral being a significant local problem. This translates into higher morbidity, low levels of rehabilitation, higher mortality risk  and, finally, higher costs. In addition, it does not permit for the implementation of strategies that may avert or delay the need for dialysis. Patients are frequently in a challenging clinical condition, often with pulmonary congestion, necessitating immediate start of hemodialysis.
Considering the relevant but not fully quantified burden of CKD in the UAE, a study of the epidemiology of CKD and referral patterns was undertaken using standardized glomerular filtration rate (GFR) prediction equations applied to all people for whom a serum creatinine value was available.
| Materials and Methods|| |
SEHA has a single unified computer system containing all clinical measurements made in its laboratories. All serum creatinine estimations originating from outpatient departments or the emergency room between 1 September 2011 and 31 October 2012 were considered for the study. The list of variables extracted included a unique reference number, age, gender, nationality of the patient, the site of origin of the sample, result of the serum creatinine and the date of the test. Serum creatinine concentration was determined by the buffered kinetic Jaffe reaction using Cobas ® Integra 400 plus and Integra 800, 6000 and 8000 analyzers (Roche Diagnostics, Dubai, P. O. Box 11397). The estimated GFR (eGRF) was calculated using the Modification of Diet in Renal Disease (MDRD) abbreviated formula:  [eGFR = 186 × (serum creatinine in mg/dL) 1.154 × age 0.203 × (0.742 if female) × (1.21 if black)]. The GFR for children aged <18 years was estimated according to the Schwartz formula:  eGFR = [(length in cm) × k]/serum creatinine in mg/dL; where k = 0.45 for infants 1-52 weeks old, k = 0.55 for children 1-13 years old, k = 0.55 for adolescent females 13-18 years old and k = 0.7 for adolescent males 13-18 years old. The length was derived by statistical tables organized by age and gender.  Individuals with eGFR values <60 mL/min/1.73 m 2 were defined as having CKD. The National Kidney Foundation criteria for CKD were used. 
Finally, people with an eGFR in the CKD range 3 to 5, identified from either the emergency department or from primary care (Ambulatory Health Services, AHS), were followed-up to determine the length of time until arrival at a nephrology out-patient clinic.
| Statistical analysis|| |
Statistics were reported by age-group, gender and nationality. Continuous variables were reported as mean values ± standard deviation (SD) and 95% confidence intervals; categorical variables were reported as proportion (percentage). Time from detection of CKD stage 3-5 to referral to an out-patient clinic was estimated using the Kaplan-Meier survival curves, censoring the time from first detection on 31 October 2012. All statistical analyses were performed by using SPSS ver. 21.0.
| Results|| |
A total of 331,360 samples from 212,314 individuals were identified, representing approximately 10% of the population (23% of the Emirati population, 6.6% of the expatriate population). Mean age was 35.6 ± 18.9 years, 49.4% were female, and 47.4% were Emirati citizens. Of the expatriates, 53.4% were from the five countries of Pakistan, India, Egypt, Bangladesh and Yemen, and the remainder were from a list of 182 other countries. [Figure 1] shows the proportion of Emirati and expatriate males and females by age who were evaluated in the study.
|Figure 1: Proportion of population by age-group with an estimation of serum creatinine between 1 September 2011 and 31 October 2012.|
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The mean serum creatinine was 61 ± 48 μmol/L in females (59 ± 43 μmol/L in Emiratis and 63 ± 54 μ Mol/L in expatriates) and 87 ± 69 μmol/L in males (80 ± 59 μmol/L in Emiratis and 92 ± 74 μ Mol/L in expatriates). The mean eGFR was 134 ± 61 mL/min in females (135 ± 58 mL/min in Emirati citizens and 132 ± 64 mL/min in expatriates) and 117 ± 65 mL/min in males (125 ± 82 mL/min in Emiratis and 112 ± 52 mL/min in expatriates). [Table 1] shows the proportion of individuals by level of CKD stratified by gender and nationality. Among Emiratis, 4.6% of males and 2.8% of females had an eGFR between CKD-3 and CKD-5. Among expatriates, 4.2% of males and 3.2% of females had an eGFR between CKD-3 and CKD-5. [Table 2] shows the percentage of individuals with an eGFR between CKD-3 and CKD-5 according to age-group. Data are stratified between Emiratis and expatriates and compared with the British figures. [Table 3] shows the average time from detection of CKD (from CKD level 3a to 5) to the arrival of the individual at a nephrology outpatient clinic, as assessed by a repeat creatinine measurement from that location. The data are stratified by the site of the original creatinine sample (AHS or emergency department).
|Table 1: Proportion of individuals by level of chronic kidney disease stratified by gender and nationality.|
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|Table 2: Proportion of residents of the United Arab Emirates with chronic kidney disease Stage 3–5 by age and nationality in comparison with the United Kingdom.|
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|Table 3: Average time from the detection of chronic kidney disease to nephrology out-patient attendance: Results are stratified by level of CKD and origin of first creatinine.|
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Finally, 1010 individuals (408 Emirati and 602 expatriates) were identified with an eGFR in the CKD-5 range. Up to the time of analysis, which was around one year after the end of the time window of the considered labo ratory tests, only 39.0% of these patients were referred to dialysis, 35.8% from the Emirati and 41.2% from the expatriate sub-groups.
| Discussion|| |
CKD is a significant contributor to the global burden of major non-communicable chronic diseases.  This study identified a significant number of people with an eGFR in the CKD range 3 to 5, with similar percentages between Emiratis and expatriates. The proportion of detected individuals by age-group is higher with respect to previous British statistics,  specifically in younger age-groups. Of the several factors possibly responsible, the most obvious is diabetes. We did not have access to blood glucose measurements in this study, but the age-adjusted prevalence of diabetes in the UAE is 19% of the population compared with 4.9% in the UK, and an additional 12.5% have impaired glucose tolerance that makes diabetes as the cause, a distinct possibility.  However, the prevalence of dialysis is still low at around 370 patients pmp. With the recent availability of resources for dialysis treatment and improvement of the quality of the service with consequent lower mortality, even a close to "normal" incidence rate is translated into a very high-prevalence growth rate.
The referral to pre-dialysis care is problematical, particularly for individuals originating in primary care. On average, three to eight months are necessary before a patient with CKD 3 to 5 attends a nephrology clinic. [Table 3] shows that those patients who present via the emergency room have shorter times to presentation; however, the figure of 247 days for patients with CKD 5 appears at odds with the times for CKD 3 and CKD 4. The reason for this is not immediately apparent but may be explained by admission and commencement of dialysis rather than referral to out-patients. Nearly all authors ,, define late presentation by quantifying the time of follow-up between presentation at a nephrology unit and the initiation of dialysis. This manuscript is the first highlighting the time between detection in primary care and presentation at an outpatient nephrology unit. The loss of three to eight months from the detection of CKD to the time the patient is seen by a nephrologist has direct consequences relating to the increased probability of losing the window of opportunity when intervention can be useful in slowing down progression  and treating or preventing secondary complications.
Patients with CKD are at high risk of cardiovascular disease. As GFR declines below 60 mL/min, the risk of cardiovascular events rises inversely with GFR. At CKD stage 5, the ageadjusted event rate increases 18-fold.  Late presentation of patients with progressive renal disease is one of the major reasons contributing to higher morbidity, mortality and cost and lower quality of life. Patients with CKD stage 5 should start dialysis early. This study showed that many CKD stage 5 patients did not present to dialysis units in the observed period of time. It has been reported that many CKD stage 3 patients are more likely to die from cardiovascular disease than to end-up on dialysis, and even in CKD stage 4, only 25-30% will reach ESRD and need renal replacement therapy.  Late presentation has many contributing factors, with late referral being the main reason. Also, many patients may waste time seeking multiple opinions in the absence of symptoms and may even travel abroad to do so. Additionally, the private health sector does not share the same computer system as the SEHA system; therefore, it is possible that patients may have opted for private care. Therefore, it is possible that some of the detected CKD stage 5 patients may have died or, in case of the expatriates, sought treatment elsewhere or returned to their country of origin. Late presentation influences not only the results of the pre-dialysis and early dialysis phases but also the likelihood of being transplanted during the first two years. Cass et al demonstrated that patients who were referred late had half the likelihood to enter the waiting list for kidney transplantation and a 35% lower likelihood to be transplanted. , In addition, late presentation clearly precludes pre emptive transplantation.
On the basis of the numbers estimated by this study, a program aiming to refer all CKD stage 3 patients would overwhelm the existing nephrology care facilities in Abu Dhabi. However, a delayed referral system restricted to patients with CKD stage 4 or 5 would reduce the emergency presentation rate to dialysis and provide for better preparation of the patients, decreasing the need for catheter placement, ,, which is associated with a significantly higher rate of morbidity and mortality.  In addition, it has been demonstrated that referral at CKD 4 has the potential to avert or delay progression of renal disease.  A possible alternative to the systematic referral of all patients with CKD stage 3 to nephrologists is the introduction of an algorithm-driven, primary care-based, disease management program utilizing reporting of automated eGFR. Such an approach has demonstrated improvement in cardiovascular risk factors and reduction in the rate of decline of renal function.  This health benefit for the patients is also associated with a significant cost saving to the health economy. It is clear from these data that a main strand of any such early detection program should be a program of public education to raise the profile of CKD.
This study has some limitations. Firstly, it was not a systematic survey but the full collection of all laboratory values performed over 1 year in a geographical entity. Therefore, the tests were performed according to certain indications and only in patients presenting to a doctor. As a consequence, the results may be biased and may over-estimate the prevalence, specifically in patients aged <60 years, because of the low sampling rate. However, in countries with adequate dialysis resources, the majority of patients are >60 years of age;  the large proportion of people in the elderly agegroup evaluated in this study (for example >80% in the Emirati population) is a clear strength as the general estimations will result in only limited bias. Secondly, we have used the MDRD equation to estimate GFR. This equation has been validated pre-dominantly in Caucasians and African Americans, and little data are available for people of South Asian origin, who account for 19.5% of the patients, and Arabs, who account for 70.7% of patients in this study. Jessani et al  have validated the MDRD and CKD-Epi equations in 581 Pakistani individuals over the age of 40 years and demonstrated that while CKD-EPI was superior to MDRD, both equations overestimated the GFR. There has been one small study of eGFR in Arabs that looked at the MDRD and Cockcroft-Gault equations in 90, predominantly male, kidney donors.  They showed that the Cockcroft-Gault formula was superior to the MDRD, but both underestimated the GFR. While this is only a very small study, if correct, it may explain the high prevalence that we are reporting.
In conclusion, this study clearly showed the need to improve the identification and referral of CKD patients and increasing the integration of dialysis units with the Abu Dhabi Health-care system. Possible solutions include not only campaigns aimed at increasing the awareness of primary care and hospital physicians to the problem of CKD but also campaigns specifically aimed at increasing the awareness of the problem within the general population and creating a functional integration of primary care physicians into the care of CKD patients. This would constitute a sustainable approach to ensure high quality of care without overinflating the requirement for or capacity of renal tertiary care.
Conflict of Interest
All authors have no conflict of interest to declare.
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United Arab Emirates
[Table 1], [Table 2], [Table 3]
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