|Year : 2020 | Volume
| Issue : 2 | Page : 103-106
The association between chronic kidney disease, waist circumference and body mass index: A case-control study from a tertiary hospital of West Bengal, India
Anirban Ghosh, Somak Kumar Das
Department of Medicine, College of Medicine and Jawaharlal Nehru Memorial Hospital, The West Bengal University of Health Sciences, Kalyani, West Bengal, India
|Date of Submission||01-Oct-2019|
|Date of Acceptance||04-Feb-2020|
|Date of Web Publication||15-Dec-2020|
Dr. Somak Kumar Das
23, Kalibari Lane, Millennium Apartment, Flat - A10, Jadavpur, Kolkata - 700 032, West Bengal
Source of Support: None, Conflict of Interest: None
Introduction: In this hospital-based study, we investigated the association between chronic kidney disease (CKD) and two globally accepted obesity parameters – waist circumference (WC) and body mass index (BMI). Aims: To investigate the association between CKD with BMI and WC. Materials and Methods: We included 416 consecutive CKD patients (age >20 years, calculated glomerular filtration rate <60 ml/min/1.73 m2) as the case group and 408 consecutive age- and sex-matched non-CKD patients as the control group for our study. after obtaining consent, all groups were tested for WC and BMI. Results: Of 416 cases, the prevalence of high WC according to the International Diabetes Federation (IDF) criteria was 37.5% and of obesity according to the Indian BMI scale was 38.46%. When compared with the control group, we found that WC (p < 0.0001, odds ratio [OR] 2.182, 95% confidence interval [CI] 1.099–1.852) and BMI (p = 0.006, OR 3.125, 95% CI 1.625–3.125) were significantly high in the CKD group. Conclusion: The parameters of obesity were found to be significantly associated with the non-edematous CKD group.
Keywords: Body mass index, chronic kidney disease, waist circumference
|How to cite this article:|
Ghosh A, Das SK. The association between chronic kidney disease, waist circumference and body mass index: A case-control study from a tertiary hospital of West Bengal, India. J Mahatma Gandhi Inst Med Sci 2020;25:103-6
|How to cite this URL:|
Ghosh A, Das SK. The association between chronic kidney disease, waist circumference and body mass index: A case-control study from a tertiary hospital of West Bengal, India. J Mahatma Gandhi Inst Med Sci [serial online] 2020 [cited 2021 Jan 27];25:103-6. Available from: https://www.jmgims.co.in/text.asp?2020/25/2/103/303425
| Introduction|| |
Chronic kidney disease (CKD) is one of the biggest public health problems globally. Patients with CKD are known to have poorer quality of daily life and decreased life-expectancy compared with individuals of the same age in the general population. CKD is defined as either structural and/or functional abnormality of the kidney or reduced glomerular filtration rate (GFR) to a level <60 ml/min/1.73 m2. The causes of CKD include the following: diabetic kidney disease, hypertension, vascular disease such as renal artery stenosis and anti-cytoplasmic antibody (ANCA)-related vasculitis, glomerular disease (primary or secondary), cystic kidney diseases, tubulointerstitial disease, urinary tract obstruction or dysfunction, recurrent kidney stone disease, congenital (birth) defects of the kidney or bladder, and unrecovered acute kidney injury.
Previous studies have shown an independent association between obesity and CKD. Recent epidemiological studies have shown that, compared to normal BMI, overweight and obese BMI categories are independently related to CKD.,
However, the role of obesity as a risk factor for myocardial infarction and mortality in patients with CKD is not well understood. Previous studies that have used body mass index (BMI) to evaluate obesity as a risk factor for adverse outcomes in CKD have shown conflicting results.,,
Since waist circumference (WC) is a more sensitive marker for central obesity and potentially less influenced by muscle mass, WC may be better indicate risk associated with obesity in a population with a high prevalence of muscle loss and malnutrition, such as individuals with CKD.
Although CKD and obesity are quite common in India, lack of detailed studies from India on their association prompted us to undertake this study. In this study, our purpose was to determine the association between BMI, WC, and CKD.
| Materials and Methods|| |
Study design and variables studied
We conducted a hospital-based case-control study at a rural tertiary hospital, College of Medicine and Jawaharlal Nehru Memorial Hospital, Kalyani, Nadia, West Bengal, from March 2018 to April 2019 after getting clearance from the institutional ethics committee. We included 500 consecutive cases of CKD with any etiology diagnosed currently or previously, by applying the modification of diet in renal disease (MDRD) equation, where the calculated glomerular filtration rate (eGFR) was <60 ml/min/1.73 m2. The case group was defined as patients of both sexes, age >20 years, and with an eGFR <60 ml/min/1.73 m2. CKD patients who were edematous were excluded from our study. After application of the exclusion criteria and excluding the patients who opted out of our study, 416 patients of non-edematous patients of CKD were included in the case group. We also included 408 consecutive age- and sex- matched non-CKD patients as controls group.
After obtaining consent, participants from both the groups were thoroughly explored through structured history-taking, general physical examination (including measurement of BMI and WC), hematological examination (including complete blood counts), lipid profile, random blood glucose, hemoglobin A1c, renal function test, and urinalysis at the time of first contact.
Measurement of WC was done using the smallest circumference between the lower ribs and iliac crests. We defined increased WC when it was >90 cm in male and >80 cm in female (according to the International Diabetes Federation [IDF] criteria for central adiposity in Indian population). BMI was calculated by dividing the weight (kg) by height2 (m2). Obesity was defined according to Indian standards, i.e., BMI >25 kg/m2.
After collecting all the data, statistical analysis was performed using SPSS (IBM, Chicago, IL, USA) software version 20 for analysis of data. Mean and standard deviation (SD) were calculated separately for each group. Unpaired (two-tailed) Student's t-test was applied to determine differences in means of various parameters between the two groups. Pearson's correlation coefficient was calculated between obesity parameters and eGFR.p < 0.05 was taken as statistically significant.
| Results|| |
In the present study, 416 cases and 408 control subjects participated. Among the cases, there were 256 males (61.53%) and 160 females 38.46%). The mean age was 53.27 years (SD: 14.36 years; range: 22–79 years). In the control arm, there were 232 men (56.86%) and 176 women (43.13%)). The mean age was 51.13 years (SD: 15.45 years, range: 21-77 years). There were no significant differences in the mean age and the distribution of age (p = 0.304). Majority of male cases were in the age group of 36–50 years, followed by those in the age group of >50 years. Most of the female cases belonged to the 51-65 years age group. In our study, we found that most of the cases were in CKD stage 4 (35.57%) followed by CKD stage 5 (32.69%). We found that hypertension and diabetes mellitus were present in 33.65% and 18.26% of the cases as compared to 20.58% and 7.84% of the controls, respectively. The other causes of CKD were lupus nephritis (2.65%), ANCA-associated vasculitis (1.44%), drug- and toxin-induced CKD (15.65%), primary glomerular disease (1.7%), cystic kidney diseases (0.98%), tubulointerstitial disease (5.79%), urinary tract obstruction or dysfunction (11.28%), recurrent kidney stone disease (6.98%), and unknown etiology (2.65%).
We analyzed obesity by measuring WC and BMI in the present study [Table 1 depicting independent sample t-test data of two groups]. Of 416 cases, the prevalence of high WC according to the IDF criteria was 37.5% and of obesity according to the Indian BMI scale was 38.46%.
|Table 1: Independent sample t-test data of chronic kidney disease and non-chronic kidney disease group|
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We found that the increased WC according to the IDF definition for Asian-Indians was strongly associated with CKD case group (p < 0.0001, odds ratio [OR] 2.182, 95% confidence interval [CI] 1.099–1.852). Females were more obese than males (19.23% vs. 18.26%) according to the WC definition. When compared to the control group, we found that BMI (P = 0.006, OR 3.125, 95% CI 1.625–3.125) was significantly high in the CKD group.
We also did Pearson's correlation study among obesity parameters and eGFR. We found that eGFR correlated significantly negatively with WC (r= −0.259,p< 0.001) and BMI (r= −0.201,p= 0.004). Age, height, weight, low-density lipoprotein (LDL), triglycerides (TG), fasting blood sugar, and postprandial sugar correlated strongly negatively, while high-density lipoprotein (HDL) correlated strongly positively [Table 2].
| Discussion|| |
Excessive abdominal fat (central obesity) has caused more health hazards than deposition of fat on the bottom and limbs. Now, it is generally accepted that the WC is the most simple and practical indicator to measure the abdominal fat. Several mechanisms exist to explain an observed association between BMI and CKD and between obesity and renal injury, including hemodynamic effects, inflammation, and renal lipotoxicity. Excess adipose tissue can lead to the activation of the sympathetic nervous system and renin angiotensin systems. Angiotensin II is elevated in the blood of obese individuals, leading to vasoconstriction of efferent arterioles. Thereby, plasma aldosterone is also slightly elevated in obese individuals, causing salt and water retention, and ultimately proteinuria., Obesity is also seen in the development focal segmental glomerulosclerosis and glomerulomegaly. Obesity is regarded as a chronic low-grade inflammation, and cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) play a major role in CKD development. IL-6 activates the adipose tissue and helps release transforming growth factor-beta 1 receptor trafficking, leading to renal fibrosis. TNF-α inhibits the activity of the nephron gene promoter in cultured podocytes, resulting in podocyte dysfunction in the obese population.,
2013, the Hallym Aging Study conducted by Oh et al on Korean population found an association between central obesity and renal function deterioration. However, Lu et al., in 2014 analyzed the data from a nationally representative cohort of 453,946 United States veterans with eGFR <60 ml/min per 1.73 m2 and found a very complex relationship between obesity and CKD. He et al. conducted a cross-sectional survey on 123,629 Chinese urban adults and found that the higher levels of BMI and WC were each positively associated with increased odds for CKD among men (OR 1.19 [95% CI 1.13–1.25] for BMI and OR 1.12 [95% CI 1.08–1.16] for WC).
However, in a systematic review and meta-analysis published by the United States-based researchers, Ahmadi et al. in 2016 observed differential association indicating obesity paradox in CKD patients. This is different from that of observed in southeastern countries. It may be due to different ethnicity.
Dong et al. observed that the adiposity parameters such as WC and BMI were significantly negatively correlated with eGFR (BMI in males r= −0.051 [<0.0001], BMI in females r= −0.014 [<0.0001] and WC in males r= −0.061 [<0.0001], WC in female r= −0.070 [<0.0001]). Another meta-analysis published in 2019 by Chang et al. noticed that the elevated BMI, WC, and waist-to-height ratio were the independent risk factors for GFR decline.
Our observations in the present study are similar to the data published from South Asian countries. We found a statistically significant association between CKD patients and obesity parameters such as BMI (p = 0.0006, OR 3.125, 95% CI 1.625–3.125) and WC (P = 0.0147, OR 2.182, 95% CI 1.099–1.852). Our data completely support the data published by Dong et al. We observed that WC, BMI, height, weight, TG, LDL, TC, and fasting blood sugar were strongly negatively correlated with eGFR decline, whereas HDL was not.
We extensively searched literature in PubMed for Indian data. However, we found only few studies done by Indian medical scientists. Of them, Singh et al., a US-based (Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA) researcher gathered Indian data from Western, Northern, and few South Indian medical institutions in 2005–2007. Another study by Trivedi et al. from Western India in 2016 showed similar association between obesity and CKD as we found in our study. However, there is a paucity of studies from Eastern India. Our study is probably the first of its kind which has gathered data from Eastern India. Although the sample size was not so large in this study, it showed similar relationship between CKD and obesity as found in previous studies from Northwest India and Southeast Asia. As our sample size was not very large, we could not make concrete comments on the relationship between obesity and CKD. Inclusion of different etiologies of CKD might have confounded our study finding. Larger studies are needed to draw better conclusions.
| Conclusion|| |
We found that the prevalence of high WC according to the IDF criteria was 37.5% and of obesity according to the Indian BMI scale was 38.46%. Non-edematous CKD showed a strong association with obesity parameters in our study. This corroborated with previous studies from western and northern parts of India and also with the data from South Asian countries. We hope that, in the future, more researchers will come forward to perform population-based study in the eastern part of the country so that we will be able to get a better picture of this association.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]