Abstract

Background and Objective


 


Chronic kidney disease (CKD) is a an increasing public health issue with growing problem worldwide. We aim to determine the prevalence of CKD and it's risk factors in a representative sample of Saudi population.


Methods


For the present study, we analyzed 5025 participants whom are between the age 18 to 105 years. All patients were from the population of the Primary health centre at King Fahad Armed Forces Hospital, Jeddah, Saudi Arabia.  All data were collected on the basis of a review of electronic medical data and through a personal interview. All patients in the present study fulfilled the revised National Kidney Foundation criteria for the diagnosis of CKD. 18 Weight (kg) and height (cm) were measured were recorded. Body mass index (BMI) values classified as  overweight or obese (BMI≥25.0 kg/m2). 19 Participants were defined as having type 2 diabetes mellitus (T2DM) according to self-report, clinical reports, use of antidiabetic agents and HbA1c (≥6.5). 20 HTN was defined when the systolic blood pressure was ≥130 mm Hg and/or diastolic blood pressure was ≥85 mm Hg in addition to receiving any medication for hypertension. 21 The total number of cohort were separated on basis of age values into five groups: <30 years, 30-39 years,  40-49 years, 50-59 years and  ≥60 years.


Main results


We analyzed 5025 participants, 1821 (36.2%) were male and 3204 (63.8%) were female. Mean age was 42.7 ± 15.8 ( minimum 18 years and maximum 105 years ).  CKD was present in  255 (5.1%) cases, 219  (85.9)%) cases were male and 36 (15.1%) cases were female with male to female ratio 5.7:1, P<0.0001. Patients with CKD were significantly older than patients without CKD, (57.9±14.6 vs. 43.1±15.4 respectively, p<0.0001). Mean BMI was not significantly different in patients with or without CKD (29.9±5.2 vs. 29.8±7.0 respectively, p=0.8). Moreover, Patients with CKD have significantly higher prevalence of T2DM, HTN, BMI≥25 and risk factors of 3 or more and less frequent of smoking prevalence than patients without CKD. Patients with T2DM were 1.6-fold to possess CKD (OR=1.6; 95% confidence interval [CI]=1.5, 1.8, or had been diagnosed with HTN (OR=2.3; 95% CI=2.0, 2.6), (p<0.0001), being a male (OR=2.6; 95% CI=2.4, 2.7), (p<0.0001) and were also less likely to be a smoker (OR=0.4; 95% CI=0.2, 0.8), (p=0.005). Regression analysis showed the risk of CKD was significantly associated with gender ((OR=10.3; 95% CI=7.1, 14.8), (p<0.0001), HTN ((OR=1.9; 95% CI=1.4, 2.6), (p<0.0001) and age  ((OR=1.04; 95% CI=1.03, 1.05), (p<0.0001). CKD prevalence is consistently statistically significant with increasing age (p<0.0001) with male predominant.


Conclusion


 


It can be concluded from this study that the prevalence of CKD among Saudis is  relatively high.


 


Older age, male gender, HTN, T2DM, overweight and obesity can be regarded as related factors.

Introduction:

Chronic kidney disease (CKD) is defined as a reduced glomerular filtration rate, increased urinary albumin excretion, or both and absolutely an epidemic of increasing prevalence with worldwide prevalence estimated to be 8–16%. 1 CKD is a an increasing public health issue with growing problem worldwide. 2 It is a global problem which affects a population’s health, putting a major load on healthcare systems. 3 The prevalence of CKD in Saudi Arabia, China and india was 5.7%, 13.0 and 17.2% respectively. 4-6 This is close to the percentage of the population with CKD in USA in the period between 1999 and 2004. 7 Five of the WHO targets are aimed at important CKD risk factors, namely: physical inactivity, high dietary salt intake, smoking, diabetes and hypertension (HTN). 8-10 Diabetes determines 33% of adult patients with CKD. 11 Further, 20% to 40% of diabetic patients will suffer from diabetic nephropathy at the end stage of their disease. 12 The number of diabetic cases increases therefore the incidence of CKD. 13 HTN is considered a strong leading cause of CKD and found in most patients with renal failure. 15 Obesity has been established as a danger leading to the development of CKD, independently of HTN, diabetes, and pre-existing renal disease. 16 In addition, smoking is one of modifiable factors which leads to the progression of CKD in community. 17 It is possible that early detection of kidney disease through community based screening programs might have an impact on this problem through earlier intervention. Little attention and limited resources are being allocated to CKD and/or its risk factors. The situation needs to change because the current data underestimates the magnitude of the problem, which, if fully realized, will pose a tremendous burden to the public health system in our country. We aim to determine the prevalence of CKD and its risk factors in a representative sample of Saudi population.

Methods:

For the present study, we analyzed 5025 participants whom are between the ages 18 to 105 years. All patients were from the population of the Primary health centre at King Fahad Armed Forces Hospital, Jeddah, Saudi Arabia. All data were collected on the basis of a review of electronic medical data and through a personal interview. All patients in the present study fulfilled the revised

National Kidney Foundation criteria for the diagnosis of CKD. 18 Weight (kg) and height (cm) were measured were recorded. Body mass index (BMI) values classified as overweight or obese (BMI≥25.0 kg/m2). 19 Participants were defined as having type 2 diabetes mellitus (T2DM) according to self-report, clinical reports, use of antidiabetic agents and HbA1c (≥6.5). 20 HTN was defined when the systolic blood pressure was ≥130 mm Hg and/or diastolic blood pressure was ≥85 mm Hg in addition to receiving any medication for hypertension. 21 The total number of cohort were separated on basis of age values into five groups: <30 years, 30-39 years, 40-49 years, 50-59 years and ≥60 years.

Statistical Analysis:

Unpaired t-test analysis and Chi square (X2) test (categorical data comparison) were used between variables to estimate the significance of different between groups for demographic and clinical laboratory. The independent relationship between the stratified risk factors and the odds ratio of having CKD were analyzed using Chi square (X2) test and logistic regression. All statistical analyses were performed using SPSS Version 23.0. The difference between groups was considered significant when P<0.05.

Table 1: Basic characteristics of the patients under study [means ± SD or number (%)]

P value Chronic kidney disease Parameters
Absent 4770 (94.9) Present 255 (5.1)
<0.0001 1602(33.6) 219(85.9) Male Gender
3168(66.4) 36(15.1) Female
<0.0001 43.1±15.4 57.9±14.6 Age (years)
0.8 29.8±7.0 29.9±5.2 Mean Body mass index (kg/m²)
0.02 3642(76.4) 211(82.7) ≥25
<0.0001 1705(35.7) 149(58.4) Type 2 diabetes mellitus
<0.0001 1144(24.0) 139(54.5) Hypertension
0.005 377(7.9) 8(3.1) Smoking
<0.0001 65.9±17.0 140.9±65.7 Serum creatinine (μmol/L)
<0.0001 1985(49.9) 74(29.0) 1 Number of Risk factors
1120(28.2) 81(31.8) 2
869(21.9) 100(39.2) ≥3

The odd ratio of risk factors for patients with chronic kidney disease

Results:

We analyzed 5025 participants, 1821 (36.2%) were male and 3204 (63.8%) were female, table 1. Mean age was 42.7 ± 15.8 ( minimum 18 years and maximum 105 years ). CKD was present in 255 (5.1%) cases, 219 (85.9)%) cases were male and 36 (15.1%) cases were female with male to female ratio 5.7:1, P<0.0001, table 2. Patients with CKD were significantly older than patients without CKD, (57.9±14.6 vs. 43.1±15.4 respectively, p<0.0001). Mean BMI was not significantly different in patients with or without CKD (29.9±5.2 vs. 29.8±7.0 respectively, p=0.8). Moreover, Patients with CKD have significantly higher prevalence of T2DM, HTN, BMI≥25 and risk factors of 3 or more and less frequent of smoking prevalence than patients without CKD. Table 3 shows patients with T2DM were 1.6-fold to possess CKD (OR=1.6; 95% confidence interval [CI]=1.5, 1.8, or had been diagnosed with HTN (OR=2.3; 95% CI=2.0, 2.6), (p<0.0001), being a male (OR=2.6; 95% CI=2.4, 2.7), (p<0.0001) and were also less likely to be a smoker (OR=0.4; 95% CI=0.2, 0.8), (p=0.005). Regression analysis showed the risk of CKD was significantly associated with gender ((OR=10.3; 95% CI=7.1, 14.8), (p<0.0001), HTN ((OR=1.9; 95% CI=1.4, 2.6), (p<0.0001) and age ((OR=1.04; 95% CI=1.03, 1.05), (p<0.0001). CKD prevalence is consistently statistically significant with increasing age (p<0.0001), figure A with male predominant, figure B.

Figure A and B: Percent of chronic kidney disease among age groups and in correlation to gender.

Discussion:

In our study, the overall prevalence of CKD was 5.1%. CKD is emerging as an important problem worldwide. 22 Data available in Saudi Arabia on the exact incidence and prevalence of CKD is limited to patients with end-stage renal disease. CKD is considered to be a multi-factorial disease, with genetic and environmental factors contributing to its pathogenesis. 23 The factors associated with the presence of CKD in our group included older age, male gender, T2DM, HTN and patients with BMI ≥ 25 kg/m2. Up to 14% of adults in the United States aged > 18 years were found to have some degree of CKD in 2007–2010. 24 CKD was common present in approximately 1 in 7 persons aged ≥ 25 years in Australia. 25 In addition to being common in developed nations, CKD is also highly prevalent in developing countries. 26 A cross-sectional study indicated prevalence of CKD in China was 10.8% while prevalence of CKD in Saudi population is around 5.7% which in concordance with our report. 27-28

We found among the elderly population (≥ 60 years), 53.7% of the subjects had CKD. Moreover, we found that males in comparison with females are diagnosed with CKD across all age groups. Renal function decreases with age in both male and female with male. Thus, the elderly population is more prone to develop CKD after various renal insults. 29 In the Chronic REnal Disease in Turkey (CREDIT) study, the odds ratios of CKD ranged from 1.45 to 2.18 for every 10-year increase in age among subjects older than 30 years of age. 30 The risk of CKD increased in people older than 65 years. 31 The number of people with CKD in the older age group (50 and older) had been increasing dramatically in the last three decades. Although the older age group constituted only 3.2% of the adult populations in Saudi Arabia, 21% of the cases of CKD were reported in this group. The number of the older age group is expected to increase to 13% of the adult population in Saudi Arabia over the next two decades. Thus, significant increases in the prevalence of CKD in older people in the future can be predicted. This trend in prevalence of CKD among people over 65 is associated with more co-morbid diseases (e.g. cardiovascular disease, diabetes, hypertension, etc.), which increases the pressure on health care services, impacts on the quality of life of patients and their families and reduces life expectancies.

Saudi Arabia is ranked among the top 10 countries in the world for the prevalence of diabetes. 32 The prevalence of T2DM is high among Saudi population and is estimated to be 34.1% in males and 27.6% in females. 33 Diabetes mellitus is the leading cause of CKD in both developed and developing countries. 34 The results of our study showed that the prevalence of T2DM among patients with CKD was 58.4%, which support that diabetes is the most common cause of CKD which within what previously reported (33-69%). 35-36 The difference in the prevalence estimated from this hospital based study and the previous community based study might be attributed to underdiagnoses of CKD in patients with T2DM. The difference could also due to an increase in the prevalence of diabetes and CKD as a complication of diabetes. A similar increase in the prevalence of diabetic kidney disease has been reported in a study carried in Tabuk, Saudi Arabia in the period 2009 to 2012. 37 Mechanisms that lead to kidney disease in diabetes included hyperfiltration injury, advanced glycosylation end products and reactive oxygen species. At the molecular level, numerous cytokines, growth factors and hormones such as transforming growth factor-beta and angiotensin II cause pathologic changes associated with diabetic nephropathy. 38

HTN is well known to be a risk factor for CKD worldwide. 39 The results of our study showed that the prevalence of HTN among patients with CKD was 54.5%. Moreover, our study indicated that the second strongest risk factor for CKD was HTN (OR = 2.3), an indicator of HTN. A retrospective study of 540 Chinese patients with CKD found that 39.6% had HTN.40 In HTN, glomerular infiltration rate has been reported to decline faster compared to those without HTN. 41 Furthermore, some studies have found a close relation between the rate of decline of glomerular infiltration rate and the development of new onset CKD after a while in patients with HTN. 42

We found overweight and obesity represent 82.7% of those with CKD. Obesity is a known risk factor for CKD and its progression. Adipose tissue and have been able to produce hormone-like peptides named adipokines or adipocytokines. Among these adipocytokines, which represent a link between obesity, HTN, and chronic nephropathy, leptins and adiponectin appear to play an important role. Leptin not only is a prohypertension element through the activation sympathetic nervous, but also is able to induce prosclerotic effects directly on the kidney. 43

Inspite the association between cigarette smoking and CKD has been observed in several previous reports, our study showed smoking was significantly lower in the CKD patients compared non-CKD groups. 44-45 This is particularly noteworthy in the Saudi Arabian population since there is a higher prevalence of current cigarette smoking compared with previous studies among males in Saudi Arabia earlier (4.7%). 46-47 Smokers had a significantly higher creatinine clearance than nonsmokers, expressing the fact that smoking-induced hyperfiltration. 48

This study of identified multiple risk factors associated with CKD. These findings underline the importance of early detection and management of those exposed to these factors in an attempt to delay CKD progression. In this study we identified several clinical risk factors associated with renal progression in our study population, including age, male gender, HTN, T2DM, overweight and obesity and others, which require further assessment. These may represent potential targets for improved management of patients with CKD that have the effect to influence the rates of CKD development.

Strengths and limitations:

This study was a retrospective and not longitudinal, preventing determination of whether any risk factors were the cause or result of CKD. Finally, this study was based on a primary care population; thus, the correct sampling weights were not used for insufficient data, thus limiting the generalization of our results to the general population of Saudi Arabia.

Conclusion:

It can be concluded from this study that the prevalence of CKD among Saudis is relatively high.

Older age, male gender, HTN, T2DM, overweight and obesity can be regarded as related factors.

Acknowledgments:

We are grateful to the staffs from the Primary care department at King Fahad Armed Forces Hospital for their valuable contributions in data collection. The authors have no conflict of interest to disclose