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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2016  |  Volume : 27  |  Issue : 4  |  Page : 781-786
Screening for kidney disease in an oil producing community in Nigeria: A pilot study

1 Department of Medicine, Renal Unit, Enugu State University Teaching Hospital, Parklane, Enugu, Nigeria
2 Department of Medicine, Renal Unit, University of Benin Teaching Hospital, Benin City, Nigeria
3 Department of Chemical Pathology, University of Benin Teaching Hospital, Benin City, Nigeria

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Date of Web Publication5-Jul-2016


Petroleum products have been associated with acute and chronic kidney disease. Nigeria is a major oil producing and exporting country. The aim of this study was to screen for kidney disease in an oil producing community in Nigeria. This was a cross-sectional study carried out in Ido, Asari-Toru Local Government Area of Rivers State. All subjects were resident in the town and those aged 18 years and above were eligible. Spot urine samples were collected for dipstick urinalysis, and venous blood was collected for estimation of serum electrolyte, urea, creatinine, and lipid profile. The estimated glomerular filtration rate (eGFR) was calculated using the Cockcroft and Gault formula. A total of 99 participants were screened: 75% were females, over 50% aged above 50 years, and the majority had low socioeconomic status. The mean eGFR of the participants was 80.2 ± 33.3 mL/min/1.73 m 2 , 32.6% of the participants had eGFR <60 mL/min, and 2% had eGFR <30 mL/min. Furthermore, 36.5% of the participants had proteinuria and 29.8% had 1 + proteinuria. There was a significant negative correlation of eGFR with a family history of diabetes mellitus (−0.35, P = 0.016), elevated systolic hypertension (−0.29, P = 0.035), and elevated total cholesterol (−0.23, P = 0.045), but there was a positive correlation with body mass index (0.24, P = 0.018). We conclude that the prevalence of kidney disease was high in the screened population in a Nigerian oil producing community.

How to cite this article:
Okafor UH, Ahmed S, Arigbodi O, Idogun S, Unuigbe E I. Screening for kidney disease in an oil producing community in Nigeria: A pilot study. Saudi J Kidney Dis Transpl 2016;27:781-6

How to cite this URL:
Okafor UH, Ahmed S, Arigbodi O, Idogun S, Unuigbe E I. Screening for kidney disease in an oil producing community in Nigeria: A pilot study. Saudi J Kidney Dis Transpl [serial online] 2016 [cited 2022 Aug 7];27:781-6. Available from: https://www.sjkdt.org/text.asp?2016/27/4/781/185257

   Introduction Top

Environmental chemicals and their products target the kidneys and initiate inhibition of renal function through a variety of mechanism. For example, heavy metals such as mercury and cadmium target the kidney after glutathione/cysteine conjugation. However, trichloroethylene and bromobenzene uptake and toxicity to the kidneys occur after their metabolism and conjugation to glutathione in the liver. [1]

Crude oil and other petroleum products contain substances such as hydrocarbon, heavy metals, and lead, which are toxic to the kidneys. Kidney injury has been reported in workers in the oil and gas sectors (both the up-stream and downstream sectors). [2] Renal cell carcinoma, glomerulonephritis, and tubulointerstitial disease presenting as acute kidney injury or chronic kidney disease (CKD) have been associated with exposure to crude oil and refined petroleum products. [3],[4],[5] Exposure to crude oil and other petroleum products can occur through skin contact, inhalation of contaminated air or soil, and ingestion of contaminated water or food. Exposure may result in localized toxicity (e.g., irritation of the skin following contact), but many health effects are caused by the systemic distribution of chemicals from crude oil. [1] Exposure varies based on the duration and concentrations of the chemicals in the contaminated material (air, water, soil, fish, etc.). Differences in exposure also occur based on location, work and personal activities, age, diet, and use of protective equipment among others. [1],[3]

Oil exploration started in Nigeria in 1951 at Iho in Imo State; however, the first success was recorded in 1956 at Oloibiri in Bayelsa State [6] and following this oil exploration has been recorded in most communities in Niger Delta States of Nigeria. There are various reports of marked environmental degradation/ pollution of this oil bearing communities; however, the assessment of impact on health of oil exploration in this oil producing communities is lacking. To date, there is no reported study relating to kidney function in any oil producing community in Nigeria.

The aim of our study was to determine the prevalence of CKD in an oil producing community in South-South Region of Nigeria.

   Subjects and Methods Top

The study was carried out in Ido, a village in Asari-Toru Local Government Area of Rivers State, Southern Region of Nigeria. Ido is an agrarian community with a population of about 2000. It is about 1 km North of Buguma City, the ancient headquarter of the Kalabari kingdom, 10 km to Port Harcourt, the Capital City of Rivers State and Commercial Center of the Niger Delta Region. The inhabitants are mainly indigenes of Kalabari extraction and the languages for communication are Kalabari and Pidgin English language. The head of the community is the paramount ruler, Amadabo of Ido, while the chairman of the Community Development Committee is the head of the community developmental programs.

This is a cross-sectional study. The study location is an oil bearing community with the evidence of past and present oil exploratory activities. The study population was to include all consenting adults aged 18 years and above. Subjects with fever, urinary tract infection, menstruation, and pregnancy were excluded from the screening. A preliminary survey of the community was made by the research group a month prior to the study. Approval for the study was obtained from the Council of Chiefs headed by the paramount ruler of the community. Ethical clearance was obtained from the Ethical Committee of the University of Benin Teaching Hospital, Benin City, Nigeria.

Information about the study was disseminated in the community through the church and the town crier. The venue of the screening was the community town hall. The details of the study were explained and an informed consent was obtained from each subject. A health talk on CKD was given prior to screening.

The biodata and medical details of each participant were documented. Weight in kilograms was recorded using a Hanson bathroom weighing scale, height in meters were taken using a stadiometer and with participants in light clothing and barefooted. Blood pressure measurements were taken in the right arm using the Accoson's mercury sphygmomanometer with participant seated. Venous blood was collected for the estimation of serum electrolytes, urea, creatinine, and lipid profile. All samples were transported in ice packs to the Chemical Pathology Laboratory of the University of Benin Hospital for analysis, and all analyses were done within 24 h. We used flame photometry method for the measurement of electrolytes, diacetyl monoxime method for urea, alkaline picrate method for creatinine, and enzymatic (Randox) method for lipid profile. The random blood sugar was assessed using Accucheck glucometer. Spot urine sample was collected from participants for analysis using urine dipstick (Combi 10).

The body mass index (BMI) was calculated using weight (kg)/height (m) [2] . Subjects with BMI ≥30 kg/m 2 were regarded as having obesity. [7]

The estimated glomerular filtration rate (eGFR) was calculated using Cockcroft and Gault formula. Subjects with eGFR <60 mL/min/1.73 m 2 were regarded as having reduced eGFR.

Proteinuria of ≥ 1+ on urinalysis was regarded as significant.

Systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg was considered as elevated blood pressure. [8]

Random blood glucose ≥200 mg/dL was elevated blood glucose. [9]

Kidney disease was defined as proteinuria ≥1+ and/or eGFR <60 mL/min/1.73 m 2 .

Mild kidney disease was defined as eGFR >60 mL/min/1.73 m 2 and/or proteinuria ≥1+, moderate and severe kidney disease were defined as eGFR 30-59 mL/min/1.73 m 2 and/or proteinuria and eGFR <30 mL/min/1.73 m 2 and/or proteinuria, respectively.

   Statistical Analysis Top

The data obtained were entered in a spreadsheet and analyzed using the Statistical Package for the Social Sciences version (SPSS) software version 17 (IBM Corporation, NY, USA). Data are presented as frequencies and mean ± standard deviation. The correlation was assessed using Pearson's correlation coefficient. P <0.05 was considered significant.

   Results Top

A total of 104 subjects gave a consent and participated in the screening, but 99 (95.2%) of them had the complete data. The age range of the participants was 18-86 years, the median age was 52 years, and the mean age was 50.7 ± 18.6 years. There were 73 (73.7%) females and 26 (26.3%) males, with a male: female ratio of 1:2.8.

Thirty-two (32.3%) and 37 (37.4%) of the study subjects had none and primary education, respectively, while 25 (25.25%) had secondary, and five (5.05%) had tertiary education. Furthermore, 38 (38.4%) of participants were traders, 15 (15.1%) were retirees (mainly junior cadre), 13 (13.1%) were civil servants, six (6.1%) were fishermen, and seven (7.1%) were students, while 20 (20.2%) were either job seekers, students, or subsistence farmers. [Table 1] showed the characteristics of the screened population.
Table 1: Characteristics of the screened population.

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The family history of hypertension and diabetes mellitus was reported in 25 (25.3%) and 13 (13.1%) participants, respectively; none had a known family history of kidney disease. Seventeen (17.2%) and six (6.1%) had a history of hypertension and diabetes mellitus, respectively.

The mean systolic blood pressure of screened population was 135 ± 32.6 mm Hg, the mean diastolic blood pressure was 79.4 ± 17.6 mm Hg; 45 (45.5%) participants had hypertension. The mean random blood glucose was 120 ± 45.9 mg/dL; eight (8.1%) of the participants had random blood glucose ≥200 mg/dL. The mean BMI of the participants was 26.3 ± 6.46 kg/m 2 ; 27 (27.3%) participants were obese.

The mean serum creatinine was 0.99 ± 0.26 mg/dL, urea was 24.9 ± 8.2 mg/dL, total cholesterol was 177.91 ± 65.87 mg/dL, low density lipoprotein was 114.64 ± 65.11 mg/dL, and high density lipoprotein was 29.20 ± 7.83 mg/dL.

The mean eGFR was 80.2 ± 33.3 mL/min/1.73 m2. Twenty-eight (28.3%) and two (2%) participants had eGFR 30-59 mL/min/1.73 m2 and <30 mL/min/1.73 m 2 , respectively. four (13.3%), nine (30.0%), 12 (40.0%), five (16.7%) of the participants aged <30, 30-50, 50-70, and above 70 years, respectively, had eGFR <60 mL/min/1.73 m 2 .

Thirty-seven (37.4%) participants had proteinuria; 31 (31.3%), six (6.1%), and one (1.0%) had 1+, 2+, and 3+ proteinuria, respectively. Three (3.0%) participant had hematuria and all were non-menstruating females.

Fifty-two (52.8%) of the studied population had kidney disease; however, only 2.0% had severe kidney disease. The details of the distribution according to age and severity are as documented in [Table 2] and [Table 3], respectively. The prevalence of kidney disease in the population was found to be high even when the participants with hypertension and diabetes mellitus were excluded.
Table 2: Distribution of kidney disease according to age group.

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Table 3: Distribution of severity of kidney disease.

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The eGFR had a negative correlation with a family history of diabetes mellitus (−0.35, P = 0.016), systolic blood pressure (−0.29, P = 0.035), and total cholesterol (−0.23, P = 0.043), but a positive correlation with BMI (0.24, P = 0.018). Only systolic blood pressure had a significant correlation on multiple regression analysis.

   Discussion Top

The study population had a mean age 50.7 ± 18.6 years with over 51.5% of them aged 50 years and above; majority (73.7%) were females. Thus, the community is an aging population with female preponderance. This could be ascribed to urban drift of the young males in search of greener pasture. Awobusuyi et al [10] have also reported a similar trend in a rural community in the Western Nigeria although the National Bureau of Statistics reported a male preponderance in the rural communities in the 2003 population census in Nigeria. [11] The majority of the subjects were of low socioeconomic status with over 69.1% of them with minimal or no education at all and none of them had lucrative job. This is a common finding in other studies in rural settings in Nigeria and other economically disadvantaged nations. [10],[11],[12],[13]

The finding of 30.3% of the studied population having eGFR <60 mL/min/1.73 m 2 is high when compared with many other community-based screening of kidney disease in some parts of Nigeria that are nonoil producing but having a similar demographic pattern. Such screening reported the prevalence rates of 8-18% of CKD. [10],[14],[15],[16] while CKD prevalence reports outside Nigeria range between 10.6% and 21%. [13],[17],[18],[19],[20] However, similar high prevalence of kidney disease has been reported in some at risk targeted screening within and outside Nigeria. [21],[22],[23],[24] About 60% of participants with kidney disease were older than 50-year-old, which could be attributed to long exposure to environment polluted by crude oil and its product. Studies in nonoil producing populations in Nigeria had reported that kidney disease is more in the 4 th and 5 th decade. [13],[17],[18],[19],[20]

The prevalence of proteinuria in our study was 37.4%. The finding is noteworthy and markedly higher when compared to other studies in nonoil producing communities in Nigeria. [8],[12],[14],[23] Thus, the population studied could actually be at greater risk of developing kidney diseases compared to similar but nonoil producing communities in Nigeria.

The majority of participants in our study with the evidence of kidney disease had either mild or moderate kidney disease as shown by the distribution of the eGFR and proteinuria. This finding is in agreement with the findings of the National Health and Nutritional Education Survey [24] that reported that severe/symptomatic CKD (Stages 4 and 5) was the tip of iceberg in the distribution of CKD in the American population.

In our study, all the participants were of the black race, 25% were male, more than half were aged above 50 years, and none had a family history of kidney disease; there was no significant correlation between these factors and kidney disease. These findings are in agreement with reports of other screening/ surveys in Nigeria by Ulasi et al, [14] Egbi et al, [15] Awobusuyi et al [10] and Afolabi et al. [25] The small sample size and the skewed nature of the age and sex distribution probably also may have contributed to these findings in this study.

As with earlier reports, [10],[26] the family history of diabetes mellitus, systolic hypertension, and total cholesterol correlated negatively with eGFR in our study.

We acknowledge some limitations in this study including the small sample size, one point screening; and no follow-up tests to confirm persistency of the abnormal parameters and identify participants with CKD. However, this does not invalidate the study as it depicts a community at high risk of kidney disease and need for large-scale study in oil producing community.

Our study showed that about 52.8% of the participants in an oil bearing community had the evidence of kidney disease detected by reduced eGFR and/or proteinuria. We suggest that the oil producing community should be studied extensively as a population at high risk for developing CKD.

This study was presented at WCN Vancouver Canada 2011.

Conflict of interest: None declared.

   References Top

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Correspondence Address:
Umezurike H Okafor
Department of Medicine, Renal Unit, Enugu State University Teaching Hospital, Parklane, Enugu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1319-2442.185257

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