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Table of Contents
Year : 2022  |  Volume : 16  |  Issue : 1  |  Page : 67-76

Determinants of physical performance in Indian kidney-transplant recipients: A prospective observational study

1 Department of Physiotherapy, Institute of Kidney Disease and Research Centre and Dr H. L. Trivedi Institute of Transplantation Sciences, Ahmedabad, Gujarat, India
2 Department of Physiotherapy, SBB College of Physiotherapy, V.S. Hospital Campus, Ahmedabad, Gujarat, India
3 Department of Nephrology, Institute of Kidney Disease and Research Centre and Dr H. L. Trivedi Institute of Transplantation Sciences, Ahmedabad, Gujarat, India

Date of Submission20-Sep-2020
Date of Acceptance08-Mar-2021
Date of Web Publication31-Mar-2022

Correspondence Address:
Dr. Harda H Shah
Senior Lecturer and PG Guide in Transplantation Rehabilitation, PhD Scholar Gujarat University, Department of physiotherapy, Institute of Kidney Disease and Research Centre and Dr H. L. Trivedi Institute of Transplantation Sciences, Gujarat University of Transplantation Sciences, Ahmedabad, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijot.ijot_117_20

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Background: Physical performance refers to the functional demonstration of task. Little is known about physical performance among Indian kidney-transplant recipients (KTRs). The objective of the present study was to evaluate the physical performance among Indian KTRs and to find its determinants from transplant, demographic, or behavior components. Methodology: In this single-center, prospective observational study, 149 KTRs with estimated glomerular filtration rate (eGFR) ≥45 ml/min/1.72 m2 and posttransplant duration (PTD) >6 months were enrolled. Physical performance was evaluated by 6 minute walk distance (6MWD), dominant hand grip strength (DHGS), numbers of 1 minute sit to stand (1MSTS), and time taken to perform 5 times sit to stand (5xSTS). Multivariate analysis was performed between transplant-related components (PTD, dialysis vintage, eGFR, and comorbidity); health behavioral components (total physical activity [TPA], sedentary time, fear of activity participation, body mass index, abdominal circumference); demographic components (age and gender); and each of the physical performance measures. Results: The average 6MWD was 392 ± 96.2 meters, the DHGS was 33.1 ± 6.8 kg, the number of 1MSTS repetitions was 24.0 ± 3.7/min, and the time taken to do 5xSTS was 10.6 ± 1.9 s among participants. When adjusted for cofounders with multivariable analyses, the health behavior of habitual physical activity was statistically significantly (P < 0.001) associated with all aspects of physical performance. Conclusion: Relatively low physical performance was seen among KTRs. Behavior of participation in physical activity contributed to the positive change in all aspects of physical performance against transplant and demographic variables, and it is the major determinant of physical performance.

Keywords: Hand grip strength, kidney transplantation, physical performance, sit-to-stand chair test, six-minute walk distance

How to cite this article:
Shah HH, Shah N, Kute V, Patel HV, Shah P. Determinants of physical performance in Indian kidney-transplant recipients: A prospective observational study. Indian J Transplant 2022;16:67-76

How to cite this URL:
Shah HH, Shah N, Kute V, Patel HV, Shah P. Determinants of physical performance in Indian kidney-transplant recipients: A prospective observational study. Indian J Transplant [serial online] 2022 [cited 2023 Feb 5];16:67-76. Available from: https://www.ijtonline.in/text.asp?2022/16/1/67/342425

  Introduction Top

Physical performance refers to the functional demonstration of task. To perform any task, integral effort of many physiological systems (neuromusculoskeletal and cardiopulmonary system) is required. Ability to do any task easily and optimally reflects the optimal health attainment. Correlates of physical performance are multifaceted and are not confined to physiological but personal/demographic, behavioral factors as well. Different demographical variables such as age, gender, race, socioeconomic condition, and education level as well as behavioral variables such as belief/attitude toward active life style, exercises, and diet have effect on physical performance. In context of kidney diseases, a successful kidney transplant decreases or reverses the deteriorated physical performance which is seen in chronic kidney disease (CKD) population.[1] Achieving optimal functionality is the upmost goal in almost all type of transplants. Receipt of a new kidney after transplant is accompanied with many new stressors and adaptive demands, such as fear of organ rejection and side effects of immunosuppressive medication.[2] Metabolic effects of transplantation medicines invite various comorbidities such as hypertension (HT), bone mineral disorders, new-onset diabetes after transplant, dyslipidemia, sarcopenia, and central obesity.[3] Type 2b fiber myopathies are seen in subjects with drug toxicity and classically presented as proximal muscle weakness. Cumulative effect may be seen in subjects with longer posttransplantation duration. Preexisting comorbidity and suboptimal graft function lead to reduced physical activity and sedentary behavior that further deteriorates the problems. Increased vulnerability to stressors results from a deregulation of multiple physiological systems, and this may directly affect the functionality of these individuals.[4] [Figure 1] represents the covariate framework for understanding different determinants of physical performance. There is scope for improvement in physical performance by modifying physiological and behavioral factors.
Figure 1: Possible determinants of physical performance after kidney transplantation

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The objective of the present study was to evaluate physical performance such as functional walking capacity and functional muscular strength–endurance and to find its strong determinants from transplant, demographic, or behavior components.

Setting and design

In this single-center, prospective observational study, kidney-transplant recipients (KTRs) from one of the tertiary transplant care centers of Western India were enrolled.

Study participants

All KTRs who came for follow-up in the nephrology outpatient department between 2018 and 2019 were invited to participate in the study. Inclusion criteria were aged between 18 and 60 years, estimated glomerular filtration rate (eGFR) ≥45 ml/min/1.72 m2, and more than 6 months of postransplant duration (PTD). Exclusion criteria were negative consent for participation, subjects with a history of hospital admission before 3 months on date of evaluation, retransplant, transplant other than kidney, surgical complication such as hernia, significant protein urea/oliguria, lymphocele, acute graft failure, active infection, and known contraindication for exercise testing.

  Methodology Top

Age, gender, and socioeconomic/education level were noted under subheading of demographic components. PTD, dialysis vintage (DV) before transplant, serum creatinine level, and presence of comorbidity (HT, diabetes mellitus [DM], cardiovascular disease, and obesity) were noted under the heading of kidney-transplant components. To evaluate health behavior component, physical activity level and sedentary time (ST) were noted using validated self-reported translated version of International Physical Activity Questionnaire (IPAQ-LF).[5] Detailed information within the domains of household-yard activities, occupational activity, self-powered transport, and leisure time physical activity was collected. Time spent in sitting was noted as ST. Energy expenditure of physical activity was expressed as metabolic equivalents of task-minutes/week (MET-min/week) by computing the intensity-specific subscores using specific guidelines provided by the IPAQ committee. For clarity of presentation, only the total physical activity (TPA) and ST are reported here. Body mass index (BMI) and abdominal circumference (AC) were measured to analyze the diet behavior indirectly. Fear and avoidance of the activity were evaluated with the use of Tampa scale of kinesiophobia (17)[6] and scored as fear of activity participation (FAP). It is a 17-item scale rated by 4-point Likert scale ranging from “strongly disagree” to “strongly agree” with scores ranging from minimum 17 to maximum 68.

Physical performance was evaluated using a series of objective measures on the same day. Six-minute walk test was carried out as per the ATS guideline.[7] Distance walked in 6 min was denoted as 6MWD. It evaluates the global and integrated response of all systems involved during exercise and reflects the functional aerobic capacity.

How fast and repeatedly one can raise from chair was evaluated using sit-to-stand test. The test was performed on a standard (46 cm) height chair without arm rest. Subjects were instructed to cross their arms on their chest and stand up, then sit again in a row as quickly as they could. The number of sit-to-stand in 1 min (1MSTS) was noted, and the time taken to complete the five sit to stand (5xSTS) was recorded in the same procedure. Both are the surrogate measures of lower limb functional endurance and strength.[8],[9]

Isometric grip strength in dominant hand without arteriovenous fistula was evaluated (dominant hand grip strength [DHGS]) using the Jamar handheld dynamometer.[10] The arm was positioned at the side of the body and the dynamometer held with elbow flexed to 90°. The participant was asked to squeeze the device as hard as possible for 3 s. Three trials were performed and the best measure recorded in kilograms. Minimum rest of 15 min was given in between all task.

Data analysis

Out of 171 screened, 149 KTRs were analyzed for the study as 6 refuse to participate, 4 were <18 years of age, 5 were meeting exclusion criteria, and 7 did not completed all assessment. Few numerical data were converted in categorical data. Socioeconomic categorization was done on basis of modified Kuppuswamy socioeconomic scale into low, upper low, lower middle, upper middle, and higher class.[11] eGFR was calculated as per the modification of diet in renal disease formula and categorized as Stage-1T (≥90), Stage-2T (60–90), and Stage-3T (≤59).[12] PTD was categorized as <1 year, 1–3 years, 3–6 years, and >6 years. DV was categorized as <12 months, between 12 and 24 months, and >24 months. Presence of comorbidity was categorized as absent (0), presence of one (1), and presence of two or more (2). The BMI was classified as underweight, normal, overweight (OW), or obese. AC was categorized as either normal or high as per normative standard for Indian population.[13] The total physical activity score was calculated in MET-min/week and categorized as low (<600 MET-min/week), moderate (>600 MET-min/week), or high (>3000 MET-min/week).

Statistical analysis

A linear regression analysis was carried out on Medistica., Pvalue.io, a Graphic User Interface to the R statistical analysis Soft ware.[14] Each of the outcome variables (6MWD, DHGS, 1MSTs, and 5xSTS) and the explanatory variables (demographic covariates, transplant-related covariates, and health behavior covariates) were tested with univariate analysis to allow statistical comparisons and finally a linear regression, multi-variate analysis was carried out. Confidence interval of 95% was kept with a P < 0.05 as a level of significance.

Patient consent

The written informed consent was taken for participation in the study and for publication of clinical details. Patients understood that all standard protocols would be followed to conceal their identity.

Ethics statement

This study was approved by the institutional ethical committee (IKDRC-ITS EC/App/28sep2018/08, CTRI trial registration number 027245, ECR/143/Inst/GJ/2013/RR-19). The whole study procedure was followed in accordance with the Declaration of Helsinki.

  Results Top

[Table 1] shows the characteristics of all study participants. Data are represented as mean ± standard deviation and median (interquartile range) or number (percentage) depending on the quantitative and qualitative nature. The average age of KTR was 39.9 ± 9.7 years. One hundred and eighteen (79%) were males. When compared with gender-matched normal reference value for BMI and AC for Indian population, 1 (0.7%) subject was underweight, 48 (32%) were OW, and 8 (6%) were obese. Ninety-eight (65%) had high AC. Sixty-one (41%) participants had no comorbidity, 72 (48%) had minimum one comorbidity, and 16 (11%) had minimum two comorbidity. Fifty-one (34%) were low physically active. The average 6MWD was 392 ± 96.2 m, DHGS was 33.1 ± 6.8 kg, the numbers of 1MSTS repetitions were 24.0 ± 3.7 per min, and the time taken to do 5xSTS was 10.6 ± 1.9 s among participants.
Table 1: Characteristic of all study participants (n=149)

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As shown in [Table 2]a, 6MWD was significantly different among the eGFR class (P = 0.04), number of comorbidities (P = 0.04), level of TPA (≤320 versus > 320 MET-min/week, P < 0.001), catagories of AC (normal and high AC, P < 0.001), catagories of BMI (normal, OW, and obese, P < 0.001) There was statistically significant negative correlation with ST (r = −0.27, P < 0.001). As shown in [Table 2]b, with a 5% risk, by adjusting for various co-variables; 6MWD of the group having TPA >320 was on average superior of 109 m to the group having TPA ≤320 (P < 0.001) [Figure 2]a. 6MWD of the group having high AC was on average inferior of 48.1 m to the group having normal AC (P < 0.001) [Figure 2]b.
Table 2: Univariate (a) and multivariate (b) regression analysis of 6.min walk distance with other variables

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Figure 2: (a) Box and whisker plot of distance walked in 6 min between category of total physical activity ≤320 metabolic equivalents of task-minutes/week and >320 metabolic equivalents of task-minutes/week (R2 = 109, P < 0.001). (b) Box and whisker plot of distance walked in 6 min between category of normal (1) and high (2) abdominal circumference (R-coefficient = −48.1, P < 0.001)

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As shown in [Table 3]a, DHGS was significantly different in each eGFR class (P = 0.025) and group of normal versus high AC (P = 0.012). There was statistical significant positive correlation with TPA (r = 0.51, P < 0.001) and negatively correlated with ST (r = −0.2, P = 0.013). By adjusting for all co-variables [Table 3]b, DHGS increased on average by 1.46 kg, when TPA increased by 100 MET-min/week (P < 0.001).
Table 3: Univariate (a) and multivariate (b) regression analysis of dominant hand grip strength with other variables

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As shown in [Table 4]a, there was statistical significantly positive linear correlation of 1MSTS with TPA (r = 0.47, P < 0.001). 1MSTS was significantly different in category of AC (normal and high AC, p = 0.019), among category of BMI (normal, OW, and obese, P < 0.01) and in category of age (>40 years, ≤40 years, P < 0.027). However; as shown in [Table 4]b, by adjusting for all co-variables, 1MSTS increased on average by 0.76 when TPA increased by 100 MET min/week (P < 0.001) 1MSTS of the OW was on an average inferior of −1.34 to the group of normal BMI (P = 0.025) [Figure 3].
Table 4: Univariate (a) and multivariate (b) regression analysis of 1 min sit to stand with other variables

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Figure 3: Box and whisker plot of sit-to-stand per minute between category of normal weight (1), over weight (2) and obese (3) (R-coefficient = −1.34, P = 0.026 for 2 vs. 1)

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[Table 5]a describes that 5xSTS was statistically different between category of high and normal AC (<0.001). There was significant positive correlation between 5xSTS and ST (r = 0.20, P = 0.001) whereas negative correlation between 5xSTS and TPA (r = −0.69, P < 0.01). By adjusting for various co-variables as shown in [Table 5]b, 5xSTS decreases on average by −0.53 s, when TPA increased by 100 MET-min/week (P < 0.001). This suggested that when physical activity increases, the time taken to do five times sit to stand decreased.
Table 5: Univariate (a) and multivariate (b) regression analysis of five times sit to stand with other variables

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In brief, the univariate analysis shown a statically significant relationship between kidney transplant-related factor (class of eGFR, number of comorbidity) behavioral factors (physical activity, diet behavior/BMI, and AC), and physical performance. PTD, DV, FAP, age, and gender were not correlated with performance. When adjusted for cofounders with multivariate analysis, only the physical activity was statistically significantly associated with all aspects of physical performance.

  Discussion Top

Evaluation of physical performance is a key element of physical fitness; its measurement is commonplace in both healthy and diseased populations. To the best of our knowledge, this is the first study describing various determinants of physical performance in Indian kidney transplant population. There are many factors that play a crucial role for being physically and functionally active. In the present study, the physical performance was evaluated among KTR.

6MWD is surrogate measure of cardiorespiratory endurance. The average 6MWD among the KTR was 392 ± 96.2 m which was low when compared with normal reference available for healthy Indian population.[15] A study done by Carvalho et al. among KTR reported an average distance of 559 ± 45 m.[16] As per the study done by Anwar et al., <304.8 m is a strong predictor of graft loss.[17] Subjects with high AC had lower 6MWD [normal AC vs. high AC; P < 0.01, [Figure 2]b. Weight gain and abdominal obesity are known complications of corticosteroid maintenance therapy. Physical inactivity, sedentary behavior, and unhealthy dietary habits further worsen complications. Majority of the participants had high AC. Central obesity increases the cardiometabolic risk, and it may have influence on aerobic capacity which may be associated with reduced endurance level among participants.[18]

Various researches have measured hand grip strength to evaluate functional upper limb strength and sarcopenia in KTRs. Normal reference in healthy Indians is available.[19] Upper limit of arm strength that reduced in 65% of the participants suggested reduced muscle mass and power. Carvalho et al. reported similar DHGS among KTRs in their study.[16]

Sit-to-stand chair tests correlate well with the isometric quadriceps' muscle endurance and power. The sit-to-stand repetitions/min reported in the literature ranged from 17.4 (CKD-5 on dialysis)[20] to 50.0 (young men).[8] OW KTRs shown lower 1MSTS test performance than normal weight individuals [OW vs. N; P = 0.026, [Figure 3]]. That difference was not observed in obese individual maybe because their number were less in sample [Table 1]. As per the study done by Strassmann et al., increased body weight has influence on sit-to-stand performance.[21] Group of subjects who were more active completed the 5xSTS in lesser time. Median of 10.9 s has been reported in other studies on adult KTR.[22]

Greenwood et al. (2012) observed that physical function reduced in subjects who were on long-term dialysis before transplant and who had longer PTD, whereas Esposito et al. had not found significant difference among different PTD (7–60 months vs. >60 months, P = 0.77).[20] In the present study, the difference in physical performance was expected among different PTD and DV, which did not visualize in the analysis maybe because of unequal frequency distribution.

Decline in physical performance is expected with aging. No statistical significant difference was seen in any performance measure with age and gender. Various barriers in activity participation and achieving optimal weight should be sought. Zelle et al. had described a negative correlation of FAP on habitual physical activity and functional capacity among KTRs.[2] In the present study, fear behavior was not statistically significant for any performance measure. Despite physicians' recommendations, most of KTRs were not physically active or participate in exercise; in the present data set, 34% were low physically active. Walking at a very slow pace was the only and main form of activity which was seen and many were sedentary. The CDC/ACSM[23] and KDOQI[12] guidelines for patients with kidney disease recommend for a total of ≥150 min/week of moderate intensity or ≥75 min/week of vigorous-intensity aerobic activity performed in sessions of at least 10-min duration (minimum range from 450 to 750 MET-min/week). Moderate exercises are the exercises in which one should feel light to somewhat hard exertion depending upon their subjective feeling. International guidelines are mostly derived from studies done on White Caucasians. Asian Indians are less physically active and are prone to obesity, type 2 diabetes mellitus and coronary heart disease. In one of the consensuses, physical activity guideline for Asian Indians suggested a total of 60 min of physical activity in which 30 min moderate-intensity aerobic activity, 15 min work-related activity, and 15 min of muscle strengthening exercises.[24] Although physical activity is considered as one of the major determinants of health, systematic data on physical activity and physical performance level in Indian renal-transplanted patients are scarce. The transplantation rehabilitation is relatively new in India. Encouragement, education, and implementation toward more active lifestyle should be addressed to change patterns of low physical activity.

Limitation of the study

Due to heterogeneity of data set and smaller sample size, the confidence interval was very wide. The results drawn from the data need to be replicated with larger sample size. Self-reported physical activity is subjected to recall bias and over-estimation. The other limitation was dietary behavior and the effect of cumulative doses of corticosteroids was not calculated directly.

  Conclusion Top

KTRs have relatively low physical performance. Behavior component, mainly participation in physical activity, contributed to the positive change in all aspects of physical performance against transplant-related and demographic variables, and it is the major determinant of physical performance.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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Bamgbola O. Metabolic consequences of modern immunosuppressive agents in solid organ transplantation. Ther Adv Endocrinol Metab 2016;7:110-27.  Back to cited text no. 3
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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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