3.0 Results
The results of the search process are summarized in figure 1. Out of 84 papers selected, 44 duplicates were removed. 40 papers were screened and 25 remained in full text screening. Finally, 7 papers were included in the review. Three of the seven papers were from the south east8,12, 15 hospital based study8and community based studies12,15. Those who took part in the hospital study were male and female patients aged≥ 18 years with sample size 908 (593 males and 315 females). The total mean age was 42.55± 15.43 years. Male (43.66±15.38 years) and female (40.48±15.31 years) (P<0.001). 86.5% were less than 60 years of age (Table 3). The study recorded a prevalence of 12%. It was observed that the population based study were adults aged 25-64 years12, recorded overall age and sex prevalence of 11.4%. The sample size was 1941 respondents. The mean age of all respondents was 43.7±13.20 years. Male (44.1± 14.1 years) and female (43.4±12.6 years). Semi urban (41.9±12.8 years) and rural population (47.6±13.0 years). Another population based study15 recorded age and sex prevalence of 7.8%. The sample 328 respondents aged≥ 18 years. The total mean age of 54.8± 12.8 years in semi-urban. The two population studies12,15 used convenience sampling technique. Univariate binary logistic analyses were used in the studies to determine the relationship between CKD and various variables. This was followed by multiple logistic regressions using the variables from univariate binary logistic analysis that were significantly associated with CKD in order to determine the risk factors of CKD. The observed risk factors was old age 12,15obesity15, diabetes mellitus12, hypertension12,15 history of renal disease15, low income occupation12. Use of traditional medication12,15haemoglobin12, central obesity12,15, glomerularnephrities8, bleaching cream and soap containing mercury12.
4.0 Discussion
This review indicates that Southeast Nigeria bear substantial risk factors. Report identified age, hypertension, obesity, history of diabetes mellitus, use of herbal medicines and prolonged use of non-steroidal anti-inflammatory analgesics as risk factors for CKD in Nigeria10. There are other emerging risk factors such as use of bleaching cream and use of soaps containing mercury25 which were in significant proportions. This calls for a tailored programme to reduce the impact of these risk factors on patients’ quality of life. A report showed that risk factors interventions (blood pressure control, glycenic control, education) may lower the risk of developing CKD26. However, strategies to improve the prevention and early detection of chronic diseases like CKD in low and middle income countries like Nigeria are not only hampered by economic considerations, but also limited data emerging from these countries. These countries have experienced rapid deterioration of their chronic disease risk and mortality profiles27. Multivariate analysis revealed that CKD correlates with some risk factors such as hypertension, use of nephrotoxins, low level of education and low income occupation among others in these studied population. Age was significant in rural communities while DM, reduce activity and low hemoglobin were associated with CKD in semi-urban. The common risk factor (herbal remedies) is a common feature of most studies in Nigeria9,12,15. These could be explained by characteristics of Nigerian societies where herbal medications were embedded in their custom. This is important because, as most of these risk factors are modifiable, adequate blood pressure control and improved education of these populations will help reduce the prevalence of CKD.
Hypertension is the commonest cause of CKD especially in people of African descent28. Initially only malignant hypertension was identified as a significant cause of kidney damage, however, more recently poor managed long term benign essential hypertension has been established as a cause of CKD/ESRD29. Naieker30 documented the characteristics of African Patient with CKD and noted that CKD affect mainly young adult aged 20 to 50 years and such patient present late with hypertension. In Nigeria, hypertension ranges from 20 to over 40% depending on the population studied31. It was observed that in a market population and slum dwellers, the prevalence of hypertension were about 40%32 and 53%33 respectively. A study recorded an overall age and sex adjusted prevalence of 26.1%, (30.1% in semi urban and 18.9% in rural)12 and noted that 48% were aware of their disease and 89% of them were on treatment. The study documented that awareness in hypertensive respondents was higher in women (51%) than men (42%) and good control was achieved in only 36% of those on medication12. These figures are high underlying the risk of CKD if blood pressure is not controlled. A high prevalence of hypertension had been consistently reported in various populations in Nigeria34,35. Hypertension and cardiovascular diseases are currently noted to disproportionately affect people in low and middle income countries like Nigeria. About 17.5 million die each year from cardiovascular disease globally, 75% of the death occur in low and middle income countries like Nigeria36. The strong association between hypertension and CKD highlight the central role of endothelial dysfunction which is contributory to initiation and progression of cardiovascular disease. This gives an idea of significant risk to which many of our individual patients were subjected. Various studies have documented low awareness in southeast Nigeria33,35. It points to the important of early diagnosis, screening and intervention against CKD and its complication. However, this becomes alarming for settings were algorithms for early screening and detection of disease risk factor are under assessed. It is argued that the effect of blood pressure control can delay onset of complication of CKD but this can achieved in a society with effective health awareness and health seeking behaviour that may enhance the opportunity for early detection and intervention.
DM is now the commonest cause of ESRD20 in North America and Europe. It accounts for 54% of incident of cases as documented in the USA renal data system37. The two community studies documented that the age and sex adjusted prevalence of DM were 5.9%12 and 7.9%15 These references double that of 3.8% for Nigerian in the latest WHO prevalence for African Countries which studied population of similar age38. One of the studies reported that 75% were aware of their disease, while 88% of those aware were on treatment and 72% of those on treatment were controlled12. Although DM did not correlate with CKD in the latter studies, but this justifies the screening exercise as identification and proper management of the disease will assist in the reduction of the prevalence. This may be because the prevalence of this population is still quiet low, hence its impact on CKD as compared with hypertension is low.
The age and sex-adjusted prevalence of the metabolic syndrome in this paper was 10.5%12. although, this is much lower than in the developed world, where using the same National Cholesterol Education program’s Adult Treatment Panel III (NCEP/ATP III) criteria, the prevalence of metabolic syndrome in the United States was found to be 34%39. It is a finding in our population that needs further surveillance.
The prevalence of markers of CKD (proteinuria) in one community study was 16.2% with the majority of them showing trace while 3.7% has significant proteinuria. Prevalence of proteinuria (≥1+) increased from 3.3% in stage 1 to 100 percent in stage 5 CKD12. This pattern is expected as higher prevalence of proteinuria is noted in advanced CKD. The persistent significant proteinuria was 5.8%15 in another community study. It was observed that Okafor et al 40 highlighting the enormity of diabetic nephropathy in Enugu, documented that the prevalence of albuminuria was 61.2%. This is alarming compared to 30% in United Kingdom while Mexican American was 31%41. Moreover studies conducted in Asian countries reported variability in the prevalence of microalbuminuria ranging from 14.2% in Iran to 36.3% in India42. The prevalence of microalbuminuria in European countries was 26.9% in Hungary while microalbumuria was 16% in Italy as well as Sweden, 9% in Germany43. There is need for screening of microalbuminuria in diabetes. This may further prevent renal damage by correcting factors such as hyperglycemia, hyperlipidemia and hypertension.
The family history of kidney disease was reported as an independent risk factor of CKD15. Among those with positive family history of kidney disease, 38% were found to have CKD. This is higher than 14.6% reported from China44 and 9.5% in KEAPS study conducted in Yorkshine Northern England45. These suggest that genetic factor may be contributing significantly in the prevalence of CKD in the southeast. This is not surprising because Ulasi et al46 had earlier reported that APOLI Genetic risk variants are common in the Igbo population of south east Nigeria and also highly associated with non-diabetic CKD in the area. These APOLI risk variants have been shown to be strongly associated with increased risk for non diabetics kidney disease among African ancestry46
The toxicity of herbal medicine is related to the mixture of active components, their interaction with drugs, contaminations and adulterations. Some herbs that have aristolochic acid as a component have been associated with nephropathy in a Chinese herbal medicine47. In Nigeria, the use of nephrotoxins contributes to about 38% of acute kidney injury9. This is in agreement with the report documented in South African by Seedat et al48 identifying herbal remedies and infection as common medical cause of Acute Kidney Injury (AKI). AKI is now an established cause of CKD49. In a study carried out in Emene Southeast Nigeria, it was observed that 53.5% in rural population used native medications while 36.5% in Semi urban admitted to the use of such medications50. Because of the kidney’s anatomic features and physiological functions as the primary eliminator of exogenous drugs and toxins, the kidney is vulnerable to various forms of injury51. Regular use of nephrotoxic medication is an independent risk factor for CKD52. Traditional remedies in Africa rarely have been analyzed and the active nephrotoxic components have not been isolated nor characterized in most cases. Many of the herbs are believe to be harmless and are commonly use for self medication. Although regulation by The Food and Drug Administration is part of the solution, increasing public awareness and education are necessary to inform the public on the potential dangers of using adulterated medicinal herbs.
The use of soaps containing mercury and bleaching creams is an emerging risk factor which was considered to be rare among Nigerians but the reverse is the case in present time. These agents have been long established to be bad for the kidneys. Report documented that the use of bleaching creams and soaps containing mercury was responsible for about half of the cases of nephritic syndrome25. This fills an important gap in the risk assessment of CKD as scanty population level data exist, particularly among patients with co-morbidities identified as vulnerable to CKD related complications. Other important nephrotoxic agents rampant in our environment are petroleum and petroleum products which are made up of hydrocarbons. Alasia et al 53 showed in a study in Port Harcourt that non-petroleum workers have high levels of hydrocarbon in their blood. This is indeed alarming. The companies should clear the environment of toxicants to safeguard the lives of rural dwellers.
The social economic factor across the study population show that majority of people are more disadvantaged in terms of income earning. The greater percentage of people is living in poverty. which the WHO define in absolute term as low income <$2/day. The minimum wage in Nigeria is N18,000/month which is approximately $108/ month and categorized as low income54. This may be the reason why the study population rely on alternative treatment such as spiritual healing and traditional native healers which are affordable. The cost of management of CKD in Nigeria is equal to $500 which is above the minimum wage of a Nigerian worker. The study identifies disparity in the accessibility of CKD risk screening awareness. This highlight the consequences of health disparity where more affluent in society have better access to health care. We noted that the respondents cite various reasons for not seeking health check including cost which does affect people’s habit where they do not seek health check when they are apparently healthy therefore attitudinal changes which impact positively on health outcome remains one of the public health messages that cannot be avoided.