Critical Appraisal and Systematic Review of Studies on the Detection of Chronic Kidney Disease in Communities


 


Introduction


            The human body has many organs with a variety of functions, and is oftentimes compared to a machine, which deteriorates with age and is damaged when inflicted with diseases. One of the essential organs in the human body is the kidney, which is responsible for the excretion of wastes and other harmful substances being absorbed and taken in by the body. Being able to filter the necessary and unnecessary chemicals inside the body, the kidney is usually one of the organs in the human body, which becomes damaged and worn during the long course of its use. Along with the other organs, the kidney is now considered one of the most susceptible organs to different diseases, such as chronic kidney disease or CKD.


Many studies have been conducted in different parts of the world to detect the occurrence, incidence and the prevalence of CKD, which is dependent on diseases, such as diabetes, hypertension, and other kidney related diseases. With the increasing problems of many patients and citizens regarding CKD, several studies have been conducted around the world for its detection, prevention and cure. This paper discusses the review of these studies in different communities and countries around the world, to validate its effectiveness and accuracy. This review can also serve as a guide if the tests will be repeated and for other future studies of other countries not mentioned in this paper.


 


Body of the Paper


            The NHANES study was effective in determining the prevalence of CKD in the US population, basing it from the calibrated serum creatinine and spot urine albumin levels. The population of the study is 15,625 non-institutionalized adults, including their race, age and gender as the basis for their results and examination. The sample population was too small for the whole population of the United States, and it would be unbelievable for the researchers to arrive at the conclusion the 11% of the whole population has CKD. I believe that the results were too conclusive, and that the study should have covered a greater number of populations. Although this study is only an estimate, it serves also as basis for other studies in CKD prevalence in other countries, so the researchers should have been more careful. The participants were randomly selected from the general population, but the ratio of men and women participants was not specified in the study.


            The NHANES study is a population-based screening program and suggests that aside from hypertension and diabetes, age is a key predictor of CKD (2005). With the tests done by the researchers in this study, it can be deduced that the tests are reliable, being able to estimate the GFR of the sample population. The results were further evaluated using statistical methods, such as the MDRD equation and the Cockcroft-Gault formula for creatinine clearance. This is somehow reliable for it was able to estimate the exact number of citizens inflicted by the disease. The study concluded that CKD is common in the population and warrants improved detection and classification using standardized criteria to improve outcomes ( 2005). Although the study is reliable, the study did not conduct further tests on the patients, such as blood pressure and blood glucose tests. The study should have checked also the existing diseases of the patients like diabetes and hypertension to ensure the validity of their results.


The KEEP study was also effective in determining the prevalence of CKD in the US population by examining the blood pressure, blood glucose, serum creatinine and hemoglobin levels of the participants. The study also based their results using the estimated GFR of the participants, and considered their existing diseases such as diabetes and hypertension. The population of the study is 6,071 adult participants of the general population, including their race and existing diseases. The sample was even smaller than the NHANES study, but is just as reliable by using additional tests, such as measuring different clinical and laboratory parameters. The ratio of men and women participants was not specified, but instead the percentages of the different participants belonging to different races. The KEEP study is a targeted cohort-screening program assessing kidney risk factors by evaluating laboratory and clinical parameters. The population was divided to further evaluate the diabetics from the non-diabetics, for diabetes is one of the diseases causing CKD. The tests are reliable, for it also based the results using the levels of eGFR, however, not validating it by using any statistical methods. The study concludes that targeted screening is effective in identifying persons with previously unidentified or poorly controlled kidney disease. This study is effective in the determination of CKD prevalence in the US population, but did not include any prevention or cure for the participants suffering from the disease. The study also suggests that close monitoring of the blood pressure, blood glucose levels and other laboratory parameters will be helpful for the early prevention and detection of the disease.


The PREVEND study is the study done in Mainland Europe conducting valid screening on spot morning urine samples to detect subjects with microalbuminuria. Microalbuminuria is the condition wherein excess protein in the body leaks into the urine (2005). The population of the study is 2,527 adults from the general population. This number is too small to predict the prevalence of CKD, although sufficient if the study aims cost-effectiveness and accuracy. The participants were also randomly selected based on gender, age, weight and race, and their conditions were examined using spot morning urine sample. The ratio of men to women participants was also not specified, although results report their significant differences in urinary creatinine excretion. The PREVEND study was able to reduce their costs by not collecting 24-hour samples from the participants, which is a tedious task both for the participants and the hospital staffs as well. It is a reliable cohort-screening program used to detect kidney problems based from the urinary albumin concentration and albumin-creatinine ratio present in the urine of the participants, and the results were evaluated using the urinary albumin excretion. This study includes also some countries outside Netherlands, but the results should not be conclusive of the prevalence of CKD, due to the small number of population and limited tests done. Although the urine samples of the participants are good basis and source of data, the study should have focused also on conducting other laboratory tests and the existing diseases of the patients. The limitations of the study include its budget cost, that was why only the spot morning urine sample was analyzed, and lacks further tests on other laboratory parameters, such as BP, and blood glucose levels.


Another study done in Europe is the Iceland study, which is a population-based screening program aiming to estimate the prevalence of CKD in the general population. The number of the sample population is 19,256, having 9229 males and 10027 females. The ratio of female participants is higher than in the males, thus affecting the results of the data based on the gender, age, and lifestyle, renal and cardiovascular risk factors of the participants. The increase in the number of women participants increases the incidence of CKD, for women are more susceptible to this disease than men are. The study used three equations for its comparison, one is based on 1/SCr, the other is based on Cockcroft-Gault equation, and the final was the MDRD equation ( 2005). The use of the three equations is beneficial for the study for the proper validation and accuracy of the data. Aside from the three equations, the study also used the levels of eGFR to evaluate the presence of absence of any kidney-related disease. With this, the study concludes that GFR estimates and the prevalence of CKD are dependent on the equation used to calculate eGFR, and a low proportion of the Icelandic population had normal kidney function according to the eGFR regardless of the equation used (2005).


The results indicate that the prevalence of renal and cardiovascular risk factors including proteinuria, hypertension, lipid abnormalities and markers of inflammation was higher among those with low eGFR than age-matched controls ( 2005). It can be deduced also that with the increase in age leads to the decrease in the estimated glomerular filtration rate, which increases the risk of CKD. Although the use of the three equations is sufficient to give accurate results, it also becomes the study’s limitation, including also the study’s limited reference to only a number of socio-demographic factors. The Iceland study is already sufficient with its number of population and the tests used, but it will also be helpful if other tests will be done, such as measuring other laboratory and clinical parameters to completely examine the participants’ conditions.


The SHARE study in Hong Kong is a population-based screening program aiming to identify the prevalence of unrecognized renal disease in asymptomatic individuals to allow further evaluation and disease-modifying interventions ( 2005). It covers 1,181 adults in the general population belonging to several large residential communities. The ratio of the men and women participants was not specified in the study. The participants were examined by measuring their blood pressure and by conducting urine dipstick for protein, blood and glucose, to determine the existence of diabetes mellitus, hypertension and other CKD-related diseases. Although the results were accurate and valid due to urinalysis, the study still lacks further validation from using statistical methods. The results show that having a family history of diabetes or hypertension increases the risk of having urine abnormalities ( 2005). With these findings, caution must be practiced in terms of lifestyle to prevent acquisition of the disease.


From the data gathered, the study concluded that sub clinical abnormalities in urinalysis or blood pressure readings are prevalent in all age groups in the adult population, so effective screening program must be warranted for further evaluation ( 2005). In addition, the public of Hong Kong must be educated toward the significance of the findings and regular health check for asymptomatic renal disease ( 2005). Despite the accuracy and validity, the SHARE study does not include the discussion referring to the participants without the family history of diabetes and hypertension. The study should have discussed this matter for evaluation that is much more effective and preventive.


The study done in Australia is the AusDiab study, which is a population-based screening program that is aimed to early stage detection and halt progression to ESRD or end-stage kidney damage (2003). The sample population of this study is 11,247 of non-institutionalized adults in the population, and the ratio of women to men participants was not specified. The population of the study was just enough to estimate the prevalence of the disease, due to the average number of Australia’s total population. Again, the participants were randomly selected, and the data collected will be used to further understand the evolution of renal disease. The results of the study were based on age, gender, race, existing diseases, and spot morning urine samples taken from the participants. These data were further evaluated by using the modified Jaffe equation, urine testing, urine microscopy, Cockcroft-Gault equation and measurement of plasma glucose and blood pressure levels. The use of the statistical methods and the tests in this study is sufficient to produce accurate and valid results. Compared to other studies, this study has evaluated its data by using a series of examinations. Urine and blood were examined and evaluated using different techniques and methods, which make the study “complete”.


Based on the data gathered, the results suggest that 16% of the Australian adult population has either proteinuria, hematuria, and/or reduced GFR, indicating the presence of kidney damage (2003). The study has documented a high prevalence of kidney damage in the general Australia population, which most likely exists in other developed countries (2003), so identification and targeting this population can provide cure or prevention not only to CKD, but also to other major disease related to CKD. Despite the accuracy and the validity of this study, it still lacks the discussion why spot midday and evening urine samples are not included.


The study made in Singapore is a population-based and high-risk screening program, which is aimed for early detection, awareness and education of the public to lessen the cases of ESRD in the future. The total population of this study is 621,183 belonging to four discrete populations having different age groups, namely, the working population, the general adult population, the pediatric population, and the specific occupational group ( 2005). The sample population of the Singapore study is by far the largest among all the populations in the study. Although the study is effective, due to the large number of its population, the study becomes expensive and time-consuming. This study did not specify the ratio of men to women participants. This study included the age, race, occupation, habits (smoking) and existing diseases of the participants, and evaluated their relation of the disease by height and weight measurements, urine, blood, cholesterol, blood sugar and standard dipstick testing. The samples were examined using estimated glomerular filtration rate, and no statistical method or tool.


The study reports that the high incidence of CKD in Singapore is attributed to diabetes and hypertension, so the study will serve as an effective intervention through disease management programs for patients with diabetes and hypertension ( 2005). The study concludes that it gave a distinct logistical advantage to the Singaporean population to determine race-specific modifiable risk factors for CKD, giving the medical community for additional information and education regarding the disease, and provide future direction for optimization of disease prevention paradigms ( 2005). However, despite its effectiveness, the study still lacks discussion regarding the relation of smoking habits to the development of CKD. This should have been elaborated to become an added prevention to the disease.


The  study is a population-based screening program, which aims to define the frequency of asymptomatic renal disease by screening a large population of patients at a relatively low cost (2005). The sample population of this study is 14,082 healthy individuals with 6759 men and 7323 women. The number of the population is just average and sufficient to produce an accurate and valid result. The participants were chosen randomly, including their age, gender and residence or location. Again, the number of women participants is larger than the number of male participants, which affected the results of the data. This is significant for women are more susceptible to CKD due to lifestyle. The data was examined using urinalysis, reagent strips, dipstick tests, blood pressure levels and urinary protein excretion rate. The tests were sufficient for they were cost-effective and were able to diagnose the presence of UTI, isolated hematuria, chronic renal failure, renal tuberculosis, kidney stones, diabetic neuropathy, and polycystic kidney diseases (2005). The only thing is the study did not use statistical tools to evaluate the results of the data. Statistical tools are useful to assess the data and make estimates on the prevalence of the disease.


The results suggest that acclimatization in Bolivia is associated with persistent proteinuria and with the increased risk of cardiovascular complications, for people in high altitudes have above normal hemoglobin levels to maintain oxygen delivery to tissues and thus raises production of erythropoietin (2005). In essence, the increase in the production of erythropoietin decreases oxygen delivery to the kidney (2005). As a solution to this, the provided treatment is the inhibition of the rennin-angiotensin system by ACE inhibitors (2005). As a conclusion, the decline of both packed cell volume and proteinuria has an additive effect in decreasing renal and cardiovascular complications of altitude polycythemia and reduce morbidity and mortality (2005). This study is effective in the detection of kidney-related problems, but lacks discussion regarding the relation of diabetes and hypertension to CKD. Another thing is that Bolivia must focus on implementing educational campaigns and prevention programs, and comprehensive training program for physicians and nurses (2005).


The Chinese study is a cross-sectional survey conducted nationally in urban and rural areas, aimed to detect and estimate the prevalence and absolute burden of CKD (2005). The sample population of this study is 15,838 with 7684 of the participants being men and 8154 of the population being women, belonging to the general adult population. The participants were chosen randomly from the urban and rural areas, and results were based their age, gender, education, occupation, and household income. The number of the population was just enough to produce accurate and valid results, but with the greater number of women participants than men participants, the results can also be altered. The samples taken from the participants include blood samples for serum creatinine tests, lipids and glucose, blood pressure levels, body weight and height, which were evaluated by serum creatinine assay, modified Jaffe reaction, and MDRD. In addition, this study produced the most accurate data, being able to be examined by several laboratories around the world. The results suggest that prevalence of CKD is relatively low compared to United States, and is similar in rural and urban areas, but higher in South than in North China ( 2005). Although the prevalence of CKD is low in China, it must not be neglected to prevent the increase in its prevalence. This data was also useful to warrant a national program aimed at detection, prevention and treatment ( 2005). But despite its effectiveness, its limitation include GFR was not directly measured in the study population, the urinary protein was not measured and persons with albuminuria or microalbuminuria were not included in the estimated prevalence of CKD, and the use of only serum creatinine level and sex to estimate kidney function ( 2005). These limitations are good sources of error in the study and must therefore be eliminated in the next studies to be conducted.


The Okinawa study is a community-based screening program aimed for CKD screening and early detection for prevention of ESRD, cardiovascular disease and premature death (2005). The sample population of the study is 154,019 of the adult population, not specifying the ratio between the men and women participants. The number of the sample population is just enough to produce valid and accurate results. The study includes the age, occupation, lifestyle and residence of the participants, and detection of hypertension, diabetes, proteinuria and cardiovascular diseases. The data gathered from the participants, such as blood pressure, serum cholesterol, triglycerides, fasting plasma glucose, and weight were examined by urinalysis and Ames dipstick measurement of serum creatinine enzyme assay, and evaluated by using the MDRD equation and the Jaffe reaction. These processes are very useful in determining the levels of creatinine or wastes in the urine of the participants and other substances present. The results suggest that lifestyle-related factors, such as over-nutrition and low levels of exercise contribute to the prevalence of CKD (2005). This means that the Japanese population must observe healthy lifestyle habits to decrease acquisition of CKD. In addition, more public information about CKD is needed to ensure compliance of individuals with screening programs and intervention strategies (2005), to help with the decrease of CKD prevalence in Japan.


The study conducted in Chennai, India is a population-based screening program, which aims to prevent and treat CKD with the use of the cheapest available drugs for the country cannot afford RRT for ESRD (2005). The sample population of the study is 21,496, not specifying the number or ratio of men to women participants. The participants were randomly chosen from the community, with inclusion parameters of age, gender, lifestyle, economic status, and education of the participants. Clinical parameters such as diabetic nephropathy, hypertensive nephropathy, diabetes, hypertension and CKD were evaluated using cheap screening programs, urinalysis, glucose and blood pressure levels, and creatinine and albumin levels, with the treatment of low-cost medicines. This study examined the presence of protein in the urine of the participants by sulphosalicylic acid and glucose by Benedict’s reagent, which are simple and cost-effective. However, due to the aim of the study to detect the prevalence of CKD and ESRD in the entire population, the use of these simple and cost-effective processes might be the cause of error and inaccuracy of the study. Despite this, the study used the MDRD equation to validate their results. The results suggest that 60% of the subjects have disease based on the questionnaire, blood pressure and the presence of albumin and glucose in the urine ( 2005). From this, it can be deduced that the Chennai study provides an effective method for prevention of chronic renal failure at the community level ( 2005), but must continue to do surveys, detect all diseases, and allocate treatment and cheap medicines to the entire population to prevent CKD. Due to this problem, the government of India can also seek help from different world organizations to fund them in the prevention of CKD and other diseases.


The last study regarding the prevalence of CKD is the study done in Mexico, which aims to offer a unique opportunity to advance our understanding of the risk factors for the susceptibility and/or progression of renal disease (2003). The sample population is 10,228 adults from the general population, not specifying the ratio of men to women participants. The number of the population is too big for just one tribe only, but if these data were sufficient to produce most accurate and valid data, then it would be enough. Inclusion parameters include the age, gender, etiology of renal disease, tribe, education, and the prevalence of the co-existing conditions of the participants. Diabetes, hypertension, and CKD were evaluated using urine and blood tests, chemistry profile, serum creatinine, complete blood cell count, HbA1c, urine albumin and urine creatinine measurements (2003). These tests are sufficient for examination, because all aspects affecting the disease were evaluated, but only lack the use of statistical tools to completely evaluate the study. The results suggest that patients with diabetes are more susceptible to CKD, which leads to facilitating the development and implementation of primary and secondary prevention strategies (2003). The study concludes that case-control study such as this one, will allow the identification of vocational and environmental risk factors, suggesting the implementation of changes in the work place and home environments to reduce the risk of kidney disease (2003). This study was able to properly assess the prevalence of CKD in one tribe of Mexico, but must still conduct further studies regarding other tribes for a more effective prevention and treatment of the disease.


 


Conclusion


            All the twelve studies were able to address the issue and the problem regarding the prevalence of CKD. Based on the results of the studies, factors such as age, gender, and the existence of diabetes and hypertension were the leading causes of CKD. From the findings of the studies, the detection of the prevalence of CKD and other kidney-related diseases in the communities will be easier, to administer the best prevention and cure. All the studies were effective in estimating the occurrence and prevalence of kidney-related diseases in different communities, whether low-income or developing countries and all studies have concrete plans on how to solve this problem. These studies were able to give awareness to the citizens all over the world to improve their lifestyle, especially in relation to their age and existing diseases.


            In my opinion, the most reliable study is the Bolivian study. This study was able to administer the detection of proteinuria and other kidney-related diseases by using cost-effective processes. This study will be very useful to other low-income countries as well, so that prevention will be properly implemented and decrease CKD incidence. In addition, this study produced reliable data, in relation to its population.


The least reliable study is the Chennai study. Although the processes used were simple and cost-effective, they could be good sources of error and confusion of data, most especially in dealing with large numbers of participants. With the lack of manpower and resources, it would be hard for the researchers to examine the entire population. The reliability and effectiveness of a community study do not only depend on the sophisticated processes used, but on the sample size of the population and their participation as well.


 



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