| Abstract|| |
The prevalence of chronic kidney disease (CKD) is increasing the world over, and it is now regarded as a public health problem. The prevalence of CKD in Nigeria remained largely unknown with hospital-based data of 2-8%. However, emerging community studies show a prevalence of 10-26.8%. This study was conducted during the 2013 world kidney day activities in Uyo, Akwa Ibom, State of Nigeria, with an estimated population of 554,906 people. Sensitizations of members of the public were ensured through the media. Trained nurses of the dialysis unit were recruited for the exercise. A well-structured questionnaire was used to collect demographic data and medical history. Subjects also had measurements of their blood pressure, random blood sugar, urinalysis, serum creatinine, and anthropometric data. Five hundred and two adults (70.6% females and 29.4% males) aged 18-78 years participated in the study. A family history of CKD was found in 4.3% of the study participants. The risk factors for CKD investigated in this population included hypertension, diabetes mellitus, obesity, proteinuria, and hematuria. The prevalence of hypertension in this sample was 30.16% [95% confidence interval (CI) 26.14-34.18%]. Only 12.58% (95% CI 9.54-15.61%) were aware of their hypertension status. There was an increasing trend in the proportion of individuals with hypertension in each higher 10 years age group (P = 0.03). The independent predictors of hypertension in this cohort were age and body mass index. The proportion of those with diabetes mellitus in the study population was 5.8% (95% CI 3.7-7.8%). Obesity was found in 31.8% individuals' proteinuria in 23.5% and hematuria in 3.0%. There is a high prevalence of risk factors for CKD in our population. Therefore, screening for early detection should be encouraged.
|How to cite this article:|
Akpan EE, Ekrikpo UE, Udo AI. Risk factors for chronic kidney disease in Urban Uyo, South-South, Nigeria. Saudi J Kidney Dis Transpl 2016;27:1011-7
|How to cite this URL:|
Akpan EE, Ekrikpo UE, Udo AI. Risk factors for chronic kidney disease in Urban Uyo, South-South, Nigeria. Saudi J Kidney Dis Transpl [serial online] 2016 [cited 2019 Nov 20];27:1011-7. Available from: http://www.sjkdt.org/text.asp?2016/27/5/1011/190878
| Introduction|| |
The prevalence of chronic kidney disease (CKD) is increasing the world over, and it is now regarded as a public health problem. , In the UK, the annual incidence of the end-stage renal disease is increasing with an estimated 100 new patients per million UK population. This prevalence is expected to rise at an annual rate of 5-8%. , In the USA, data from the third National Health and Nutrition Examination Survey showed that up to 11% of the general adult population has some degree of CKD, including more than 8 million individuals with glomerular filtration rates (GFRs) of <60 mL/min.  The number of people at increased risk of developing or having undiagnosed CKD, especially those with diabetes or hypertension, has risen over the years, and this trend is expected to continue. To date, prevention programs have been nonexistent in Nigeria, and the prevalence of CKD remains largely unknown. Hospital-based data on the prevalence of kidney disease in Nigeria show a prevalence of 2-8%. , However, emerging community studies show a prevalence of 10- 26.8%. ,,
CKD is a progressive disease. However, early screening, detection with good management [mainly focusing on blood pressure (BP), lipid and glycemic control, together with smoking cessation, and avoiding nephrotoxic drugs] can delay or even retard progression. In resource-poor countries like ours, where the cost of renal replacement therapies is beyond the reach of most citizens, this remains the most viable option of management of CKD.
| Subjects and Methods|| |
The study was conducted during the 2013 world kidney day activities in Uyo Urban, Akwa Ibom State located in South-South part of Nigeria. It comprises Uyo, part of Itu and Uruan Local Government Areas with an estimated population of 554,906 people according to 2006 Nigerian Census.  The people of Uyo are basically civil servant with few engaging in subsistence farming. Adequate sensitization to world kidney day activities of members of the public was ensured through radio announcement and live television programs before the day of screening. Trained nurses of the dialysis unit were recruited for the exercise.
A well-structured questionnaire was used to collect demographic data such as age, sex, and past and present medical history. Subjects had their BP, blood sugar, urinalysis, and serum creatinine measured. Weight, height, and body mass index (BMI) were also checked.
The BP of the respondents was measured using Accoson's Aneroid Sphygmomanometer made in England with an appropriate cuff size in the right arm in the sitting position after 5 minutes rest. The mean of two readings was considered as the subject's BP. Random blood sugar test was done using Accu-Chek Active glucometer manufactured by Roche India Pvt. Ltd., and urinalysis was done with Combi9 urine dipstick. Subjects had their serum creatinine assayed using Roche's Reflotron Plus Clinical chemistry analyzer machine. Weight and height were measured using Seca stadiometer. Obesity was defined using the WHO criteria,  while hypertension was diagnosed based on the Joint National Committee (JNC) VII criteria.  Subjects were considered hypertensive if the BP was ≥140/90 mm Hg or on current use of antihypertensive medications. Diabetes mellitus was diagnosed based on the WHO criteria of fasting plasma glucose of 7 mmol/L and above or random plasma glucose of 11.1 mmol/L and above  or subjects on treatment for diabetes. Dipstick proteinuria was graded as 1+ (30 mg/dL), 2+ (100 mg/ dL), and 3+ (500 mg/dL) or negative. Subjects with abnormal serum creatinine, overt proteinuria, hypertension, and diabetes mellitus were referred to their appropriate specialist at the University of Uyo Teaching Hospital. Ethical clearance was obtained from the University of Uyo Teaching Hospital Ethical Review Committee. The risk factors for CKD investigated in this population included hypertension, diabetes mellitus, obesity (and overweight), proteinuria, and hematuria. GFR was estimated using the four-variable of modification of diet in renal disease (MDRD) formula.  Chronic kidney disease was defined, in this study, as the presence of estimate GFR (eGFR) <60 mL/min/1.73 m 2 and/or the presence of dipstick proteinuria.
Data analysis was performed using STATA 10, StataCorp, College Station, Texas, USA. Prevalence was reported as percentages with their 95% confidence intervals. Continuous data were reported as mean with their respective standard deviation and comparison of mean undertaken using the Student's t-test. A P <0.05 was deemed statistically significant. A multivariate logistic regression model was used to identify independent predictors of hypertension in the study population.
| Results|| |
Five hundred and two adults (70.6% females and 29.4% males) aged 18-78 years and living in urban areas participated in the study. A family history of CKD was found in 4.3% of the study participants. [Table 1] summarizes the characteristics of the participants.
The risk factors for CKD investigated in this population included hypertension, diabetes mellitus, obesity (and over-weight), proteinuria, and hematuria.
The prevalence of hypertension in this population was 30.2% (95% CI 26.1-34.2%). Only 12.6% (95% CI 9.54-15.61%) were aware of their positive hypertension status. The female population had a hypertension prevalence of 28.5% (95% CI 23.7-33.2%) and the male population of 33.8% (95% CI 26.1-41.5%), P = 0.23.
There was an increasing trend in the proportion of individuals who were hypertensive in each age group (P = 0.03) with 9.1% of individuals <20 years having hypertension, while 63.6% of those in the 61-70 years age group were hypertensive [Figure 1]. In the 41-50 years age group, about 40% had hypertension. A family history of hypertension was positive in 27.8%.
The independent predictors of hypertension in this cohort were age and BMI [Table 2]. There was a 7.7% (95% CI 4.6-11%) increased likelihood of being hypertensive for every one year increase in age after adjusting for gender, BMI, waist circumference, and the presence of hematuria or proteinuria.
About 4.3% and 12.5% of the study participants had a personal or family history of diabetes mellitus, respectively. The proportion of those with diabetes mellitus in the study population was 5.8% (95% CI 3.7-7.8%). There was no significant difference between the proportion of males with diabetes compared to that of females (4.7% vs. 6.2%, P = 0.52).
There were 31.8% (95% CI 27.7-36.0%) obese individuals (16.8% among males vs. 38.1% among females, P <0.001). Obesity or overweight was observed in 69.4% of cases (95% CI 65.3-73.5%). Males with high waist circumference were significantly fewer than their female counterpart (50% vs. 72.7%, P <0.001).
Proteinuria was found in 23.5% (95% CI 19.8-27.2%) with no significant difference between both genders (23.1% for males vs. 23.7% for females, P = 0.90). Hematuria, on the other hand, was present in only 3.0% (95% CI 1.5-4.5%).
The prevalence of CKD was 24.2% (95% CI 20.5-27.9%). Of these, 1.8% had an eGFR <60 mL/min/1.73 m 2 . Only three (1.4%) of the participants were aware that they had CKD before the screening program.
| Discussion|| |
We report the prevalence of risk factors for CKD in Uyo urban which comprises Uyo Capital City, part of Itu and Uruan Local Government areas of Akwa Ibom, State of Nigeria. The focus was on hypertension, diabetes, obesity, proteinuria, and hematuria. A number of factors have been shown to be associated with CKD, these include, aging, hypertension, diabetes mellitus, dyslipidemia, obesity, and smoking. An interventional approach that would prevent the development and progression of CKD at a community level would thus involve the need to control all these factors.
Hypertension was significantly higher among the subjects accounting for about a third of the study population. This is slightly higher than the report among civil servants in Kano  and Nsukka.  This was however lower than that reported in a survey done in Port Harcourt, South-South Nigeria.  However, a study by Amira et al  showed the prevalence as high as 33.3% in Lagos, while a study in Ile-Ife revealed that 37.7% of market respondents had hypertension.  These values were higher than what we found in this study. This study revealed that quite a large number respondent was not aware of their hypertensive status. Only 12.6% of the 30.2% of hypertensives were aware of their status. This was comparable to findings in Port Harcourt.  There was a consistent increase in BP with age. This has been noted in several other studies. , It has been found that hypertension increases with increasing age to a point that half of the people aged 60-69 and three-quarter of those who are 70 years and above have a systolic hypertension.  Hypertension was more prevalent among males compared with females. Similar findings were noted in earlier studies. , Independent predictors of hypertension were increase in age and obesity; this was consistent with a similar study in Kogi state, Nigeria.  Age remained an independent risk factor for hypertension even after adjustment for BMI, proteinuria, and hematuria.
The world over, diabetes remains the leading cause of CKD,  and in Nigeria, there has been an increasing trend in number of patients with CKD secondary to DM.  Diabetes mellitus was found in 5.8% of subjects in our study with no statistical difference between males and females. This was higher than Kano report and that of non-communicable disease survey , although lower than 7% in Kinshasa. 
It is widely known that obesity increases the risk for hypertension and diabetes mellitus, the two most common etiologies for end-stage kidney disease. However, obesity itself likely has an independent effect on renal hemodynamics. Multiple mechanisms have been postulated whereby obesity directly affects the kidney function including hyperfiltration, increased glomerular capillary wall tension, and podocyte stress.
We found that 31.8% of our subjects were obese while 69.4% were either obese or overweight. Females were more likely to be obese than males. Our findings were similar to that of Konawa, Japan,  but higher than earlier studies done in most Nigeria survey which showed a range of 10-22.6%. , This may be attributed to the fact that most of our subjects were a civil servant and consequently lead sedentary lifestyles. This underscores the need for the urgent enlightenment of the populace on the need for exercise and change in attitude toward Westernized diet.
Proteinuria is an early marker of kidney dysfunction and also a strong contributor to rapid progression and deterioration in renal function. The prevalence of proteinuria was 23.5% among our screened subjects; there was no statistically significant difference between males and females. This value was higher than 19.6% in Kano,  19.9% in Lagos,  and 4.3% reported in Enugu.  It was however lower than 29.7% reported in Ile-Ife and from Rivers state. , This high prevalence of proteinuria among our population underscores the need for routine screening of patients by the general practitioners for its early detection and management.
The prevalence of hematuria was 3% of the screened population. Hematuria, especially when persistent, has been known not only as a marker of kidney dysfunction but may also contribute to progressive kidney dysfunction.  It may be a marker of glomerular disease or of some hereditary kidney disease such Alport syndrome or IgA nephropathy. It may also be a marker of infection with schistosomiasis hematobium, especially in a susceptible population like ours.
| Limitations|| |
There is a significant risk of overestimating the prevalence of CKD in this study because dipstick proteinuria was performed only once. It would have been ideal to determine the persistence of proteinuria three months after the initial dipstick test, but this was not done because of financial constraints. Patients found to have proteinuria, however, were referred to the appropriate clinic for further evaluation.
| Conclusion|| |
Risk factors for CKD are increasing; therefore, there is a need for routine screening to prevent the dire consequences of progression.
Conflict of interest: None declared.
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Effiong Ekong Akpan
Department of Internal Medicine, University of Uyo Teaching Hospital, Uyo
[Table 1], [Table 2]