Annals of African Medicine

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 20  |  Issue : 2  |  Page : 92--97

Screening for chronic kidney disease in an urban population in Nigeria


Umezurike Hughes Okafor, Obianuju Ogbobe, Nkem Ugwu, Chidinma Nebo, Promise Asogwa 
 Renal Unit, Department of Medicine, ESUT Teaching Hospital, Parklane Enugu, Nigeria

Correspondence Address:
Dr. Umezurike Hughes Okafor
Department of Medicine, Renal Unit, ESUT Teaching Hospital Parklane, Enugu
Nigeria

Abstract

Background: Chronic kidney disease has been reported to be on the increase globally and worse in the developing countries. Early detection has been associated with a better outcome. The objective of the study is to screen for kidney disease and its risk factors in the urban population in Nigeria. Materials and Methods: This is a cross-sectional nonrandomized study of residents of Enugu metropolis of Nigeria. Ethical approval was obtained from the ethical committee of the hospital. The study population was consecutive subjects aged 18 years and above who gave consent to the study. The details of the study were explained to the participants and informed consent obtained. The biodata, relevant clinical parameters, and blood and urine samples were obtained from each participant. The serum creatinine and urine protein of each participant were assessed. The estimated glomerular filtration rate (eGFR) was calculated using the modification of diet in renal disease epidemiology formula. Kidney disease is defined as eGFR <60 ml/min/1.73 m2 and/or proteinuria. The data obtained were analyzed using SPSS software version 20. The results were presented in tables and charts as frequencies, mean and standard deviation. P < 0.05 was considered statistically significant. Results: Four hundred and sixty-six participants participated in the study, 77.3% were females with a male: female ratio of 1:3.4. The age range was 18–90 years with a mean of 35.7 ± 12.7 years; 11.8%, 1.3%, and 0.6% had hypertension, diabetes mellitus, and kidney disease, respectively. Systolic blood pressures (BPs) of 140 mmHg and above and diastolic BP of 90 mmHg and above were found in 20% and 18.5% of the participants, respectively. Furthermore, 16.9% of the participants had a random blood glucose >11 mmol/l. The range of serum creatinine was 27.3–1029.1 μmol/l with a median of 69.1umol/l. eGFR <60 ml/min/1.73 m2 was found in 6.6% and proteinuria in 18.2%; however, 23.1% of the participants had kidney disease detected by eGFR <60 ml/min/1.73 m2 and/or proteinuria. Age, male sex, BP, and body mass index were found to have a statistically significant inverse relationship with kidney function. Conclusion: Prevalence of kidney disease in an urban population in Nigeria is high. The risk factors were hypertension, increasing age, male sex, and obesity.



How to cite this article:
Okafor UH, Ogbobe O, Ugwu N, Nebo C, Asogwa P. Screening for chronic kidney disease in an urban population in Nigeria.Ann Afr Med 2021;20:92-97


How to cite this URL:
Okafor UH, Ogbobe O, Ugwu N, Nebo C, Asogwa P. Screening for chronic kidney disease in an urban population in Nigeria. Ann Afr Med [serial online] 2021 [cited 2022 May 19 ];20:92-97
Available from: https://www.annalsafrmed.org/text.asp?2021/20/2/92/320036


Full Text



 Introduction



The kidneys play a key role in maintaining the functional well-being of an individual. It has various functions which in addition to the removal of waste products of metabolism also includes homeostasis of blood pressure (BP), hemoglobin, calcium, phosphate, water, and chemical content of the body.[1] It also plays a role in gluconeogenesis, insulin metabolism, and nutrition.[1] These functions are determined by its capacity to filter, absorb, or remove water and substances; activate Vitamin D; and produce erythropoietin, renin, and glucose.[1],[2] Thus, impairment in kidney function is associated with myriads of clinical manifestations and functional impairment.

Impairment in kidney functions results from various acute or chronic conditions causing acute or chronic kidney disease (CKD). This results in the accumulation of waste and other chemicals hitherto excreted by the kidney; these chemicals are thus used as surrogate markers of kidney functions. However, because of multiple interference in the concentration of these chemicals in the body, only a few of them that have the least interference are used as markers of kidney functions. Creatinine and urea are the most preferred endogenous substances, although the clearance of creatinine correlates better with kidney function than serum concentration.[3] Other endogenous substances such as cystatin C and uric acid have been used as surrogate markers of kidney function.[4]

In Nigeria, kidney disease with an associated functional impairment has been widely reported, but the prevalence varies depending on the population studied and type of kidney disease. Chukwuonye et al.[5] in a meta-analysis and systematic review of population-based studies on the prevalence of CKD in Nigeria reported a prevalence of 2.5%–26% depending on the population studied. Various communicable and noncommunicable diseases including hypertension, diabetes mellitus (DM), glomerulonephritis, infections, obesity, obstructive urinary diseases, and cystic kidney diseases have been reported as causes of kidney diseases and associated impairment in kidney functions in Nigeria.[6] Family history of kidney disease, socioeconomic status, cigarette smoking, and analgesic abuse had also been associated with the development of kidney disease.[7]

Early detection of kidney disease has been associated with improvement in clinical outcome. However, the majority of patients with kidney diseases present late in Nigeria.[8],[9] Thus, targeted screening of kidney disease will lead to early diagnosis, while population-based screening as in this study determine the prevalence and risk factors of kidney disease in the population.

The aim of this study is to screen for kidney disease in an urban population in Enugu State, Nigeria.

 Materials and Methods



This is a population-based cross-sectional study, and the study location is Enugu metropolis in Enugu State, Nigeria. This was a part of the event of world kidney day celebration of the world kidney day team ESUT Teaching Hospital Parklane Enugu, Enugu State, Nigeria. Enugu metropolis is one of the oldest urban cities in Nigeria. It was the headquarters of the then Eastern Nigeria, East Central State, Anambra State, and presently Enugu state. The populace are mainly civil servants; however, the city is the attraction and hub of the Easterners in Nigeria, especially the Igbos. The World Kidney Day was publicized using the print and electronic media. Health talk was given by a member of the team, and all attendees had clinical and laboratory assessment.

Study population

The study population was adult participants who gave consent for the study after the details of the study were explained to them. However, participants with features suggestive of urinary tract infection and febrile illness, pregnant, and menstruating women or those that did not give consent were excluded from the study. However, those that were excluded were also screened as part of the world kidney day celebration.

Study protocol

All the participants were evaluated clinically using an interviewer-administered questionnaire and the parameters collected include age, sex, past history of hypertension, DM, and kidney disease. The weight and height were measured using the standard weighing scale in kilograms and stadiometer in centimeters with the participant standing erect, barefooted, and without heavy clothing. The BP was measured using Acusson's sphygmomanometer with the patient seated in a back chair with the arm resting on a table. The auscultatory method was used; systolic and diastolic BP were measured at the 1st and 5th phase of Korotkoff sound, respectively. The BP was measured twice and the average of the 2 was used for the study. Spot urine was collected and urinalysis done using Combi 2 Uristix. Random blood glucose was assessed using Accu-Check glucometer. Three milliliters of blood was collected from each participant, and serum creatinine was estimated using Cobas E 411 autoanalyzer.

The body mass index (BMI) of each participant was calculated using body weight in kilogram divided by the square of height in meters. The glomerular filtration rate of each participant was estimated using the modification of diet in renal disease epidemiology formula.

Definitions

Hypertension – Systolic BP >140 mmHg and/or diastolic BP >90 mmHg[10]Impaired glucose/DM – random blood glucose >200 mg[11]Obesity –BMI >30[12]Known hypertensive – previously diagnosed of hypertensionKnown diabetic – previously diagnosed of DMFamily history of DM – history of DM in a relativeFamily history of hypertension – history of hypertension in a relativeFamily history of kidney disease – history of kidney disease in a relativePrevalence of hypertension – history of hypertension + new hypertensionPrevalence of DM – history of DM + new DMProteinuria – protein detected in urine using Uristix.[13]Kidney disease – estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 ± proteinuria.[14]

Data analysis

The data obtained were sorted, entered into a spread sheet, and analyzed using SPSS version 20 (IBM NYC USA, 2011). The numerical variables were expressed as mean ± standard deviation or median depending on the distribution. The nonnumerical variables were expressed as frequencies. Pearson's correlation was used to assess the various correlations. P < 0.05 was considered statistically significant.

 Results



Biodata

Four hundred and sixty-six participants participated in the study, 360 (77.3%) were females with a male-to-female ratio of 1:3.4. The age range was 16–90 years, with a mean of 35.7 ± 12.7 years. The details of age distribution are documented in [Table 1].{Table 1}

Clinical characteristics

Clinical characteristics showed that 25.3% were hypertensive, 3.1% were diabetic, and 17.3% were obese. The details of the clinical characteristics are as shown in [Table 1].

Kidney function

The serum creatinine ranged from 27.3 to 1029.1umol/l, with a median of 69.1umol/l. Thirty participants (6.4%) had eGFR <60 ml/min/1.73 m2. The details of the distribution of the eGFR are as documented in [Figure 1].{Figure 1}

Kidney disease

Proteinuria was recorded in 18.2% of the participants, and 23.1% had kidney disease. The distribution of the severity of kidney disease is shown in [Figure 2].{Figure 2}

Correlations

BP, BMI, age, and male sex had a significant negative relationship with eGFR. The details are shown in [Table 2].{Table 2}

 Discussion



This population-based screening was to detect preclinical kidney disease, highlight the enormity of the disease, and probably aid in increasing awareness and educating the populace. The demographic parameters are consistent with most other population-based screening of kidney disease, especially in urban and semi-urban populations that usually have females and the young age group in the majority.[15],[16],[17] This is usually attributed to men and older age group not been willing to participate in community-based screening as the majority of them are working class.

Kidney disease is defined as loss of kidney function as depicted by eGFR <60 ml/min or evidence of kidney injury depicted by proteinuria/hematuria on urinalysis or structural defect in imaging.[14] In this study, using eGFR and proteinuria, 23.1% had kidney disease, with 6.6% and 18.2% having eGFR <60 ml/min and proteinuria, respectively. Ulasi et al.[18] in a study of the semi-urban and rural population of Southeastern Nigeria reported a similar prevalence of proteinuria of 16.2%; however, they had a lower prevalence of kidney disease of 11.7%, Abioye-Kuteyi et al.[19] reported the prevalence of CKD of 19.9% in Southwestern Nigeria, and Nalado et al.[20] in northwestern Nigeria reported a prevalence of 26% and 23.6% for kidney disease and proteinuria, respectively, which also consistent with our study. The prevalence of kidney disease in North Central and South-South Nigeria was 2.5% and 24.5%, respectively.[16],[21] These disparities in the prevalence of CKD in various parts of Nigeria could be attributed to various sociocultural disparities of the studied population and also disparity in the study procedure including estimation of glomerular filtration rate and assessing proteinuria. This has also been observed globally; however, Hill et al.[22] in systemic review and meta-analysis of about 6000 articles reported a mean global prevalence of CKD of 13.4%.

The prevalence and incidence of CKD have been increasing with a major impact in the developing/resource-poor countries. This has been attributed to the increasing burden of risk factors of CKD. These risk factors are enormous and include the traditional or nontraditional risk factors.[23] However, hypertension, obesity, male sex, and advancing age were found to be significant predictors of kidney disease in this study.

One hundred and eighteen (25.3%) participants were hypertensive and 11.8% had a family history of hypertension in this study. This is consistent with other population-based studies in Nigeria.[15],[18],[20] Globally, hypertension is the second most common cause of CKD, and it contributes about 30% of causes of CKD in Nigeria. Thus, screening of the at-risk population for hypertension leads to early diagnosis and intervention, which has been reported to reduce the incidence and progression of CKD.[24]

CKD has been associated with advancing age, and kidney function falls by 1% yearly as from 40 years of age.[25] This has been attributed in addition to the aging of the kidneys to a higher prevalence of some other clinical states that cause CKD such as DM, hypertension, and other cardiovascular diseases. The mean age of the participants in this study was <40 years, and this could explain the low prevalence of impaired kidney function.

Estrogen and other sex hormones have been noted to have a positive impact on the incidence and progression of CKD.[26] This explains the higher incidence and worse outcome of CKD in males. Furthermore, obesity, especially truncal obesity increases the risk and progression of CKD. The mean BMI of the studied population was more than 25, with about 17% being obese. This is similar to studies in other parts of Nigeria and Africa.[20],[27] Obesity causes kidney diseases indirectly through hypertension, DM, and cardiovascular disease and directly by production of oxidative radicals, deposition of lipids in the kidneys, activation of renin–angiotensin–aldosterone system with associated glomerular hypertension, glomerular hyperfiltration, and glomerular sclerosis.

The prevalence of DM of 3.1% is lower than reported in other studies in a similar population.[15],[17],[18] However, it is higher than the earlier reported prevalence in Nigeria national survey.[28] This reflects the increasing incidence of DM in our population. Although DM is not a significant predictor of CKD in this study, its important role in the cause and progression of kidney disease cannot be ignored. It is the most common cause of CKD globally, especially in the Western population.[11]

It has been variously reported that more than 90% of patients with CKD are unaware including those with clinical markers.[29] The screening of those at risk will aid in early diagnosis and encourage early intervention which has been associated with better outcome.[12]

Majority of the participants detected with kidney disease had mild kidney disease (71.3%), and only 1.9% had severe kidney disease with eGFR <30 ml/min/1.73 m2. This is consistent with other studies which have shown that patients with clinical manifestation of CKD are the tip of the iceberg.[5],[18],[22],[30] This depicts the need for screening of patients for CKD, especially those at risk to ensure early diagnosis and prompt intervention.

This study had some limitations, which include the cross-sectional and nonrandomized nature leading to selection bias. Men also did not turn out in large numbers. Most of them are traders, and it is difficult for them to leave their place of business for long periods. Although the renal parameters were not repeated after the 3 months, the results depict the burden of kidney disease and the risk factors of CKD in this population.

 Conclusion



The prevalence of CKD and associated risk factors in the studied population is high; the majority of them had mild kidney disease, which is usually asymptomatic. Thus, there is a need for screening of at risk patients including the aged, hypertensive, diabetic, and the obese to encourage early diagnosis and intervention.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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