Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients
Background: Online dialysis clearance monitors typically provide an accurate value for Kt. A value for V (total body water [TBW]) is required to calculate Kt/V, the measure of the adequacy of the delivered dialysis in hemodialysis (HD) patients. Using bioimpedance spectroscopy (BIS), we previously d...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SAGE Publishing
2022-11-01
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| Series: | Canadian Journal of Kidney Health and Disease |
| Online Access: | https://doi.org/10.1177/20543581221137180 |
| _version_ | 1811189085456302080 |
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| author | Nazanin Noori Arti Sharma Parpia Ron Wald Marc B. Goldstein |
| author_facet | Nazanin Noori Arti Sharma Parpia Ron Wald Marc B. Goldstein |
| author_sort | Nazanin Noori |
| collection | DOAJ |
| description | Background: Online dialysis clearance monitors typically provide an accurate value for Kt. A value for V (total body water [TBW]) is required to calculate Kt/V, the measure of the adequacy of the delivered dialysis in hemodialysis (HD) patients. Using bioimpedance spectroscopy (BIS), we previously developed 2 sex-specific equations for the estimation of the TBW, which we have chosen to name the St Michael’s Hospital (SMH) equations. Objective: The objective of this study was to validate the SMH equations in a second distinct population of patients. Design: Cross-sectional study. Setting: Single center hemodialysis unit at St Michael’s Hospital, a tertiary care teaching hospital, in Toronto, Canada. Patients: Eighty-one adult HD patients who had been receiving conventional maintenance HD for at least 3 months. Measurements: Anthropometric measurements including weight, height, and waist circumference were collected. TBW was measured by BIS using the Body Composition Monitor (Fresenius Medical Care, Bad Homburg, Germany). Methods: The Bland-Altman method to calculate the bias and limits of agreement and the difference plot analysis were used to evaluate the difference between the BIS-TBW and the TBW derived from our equations (SMH equation) in this validation cohort. Results: The TBW values based on our equations had a high correlation with BIS-TBW (correlation coefficients = 0.93, P values < .01, bias = 1.8 [95% CI: 1-2.6] liter). Application of SMH equations closely predicted Kt/V, based on BIS value, in all categories of waist circumference. Limitations: Small sample size, single-center, not including peritoneal dialysis patients. A larger and more heterogeneous sample with more patients at the extremes of body mass index would allow for more detailed sub-group analyses in different races and different anthropometric categories to better understand the performance of these equations in discrete sub-groups of patients. Conclusions: In maintenance HD patients, our previously derived equations to estimate the TBW using weight and waist circumference appear to be valid in a distinct patient population. Given the centrality of TBW to the calculation of small molecule clearance, the SMH equations may enhance the measurement of dialysis adequacy and inform practice. |
| first_indexed | 2024-04-11T14:29:59Z |
| format | Article |
| id | doaj.art-7dd46797f7e444718c599a6a92ef8b08 |
| institution | Directory Open Access Journal |
| issn | 2054-3581 |
| language | English |
| last_indexed | 2024-04-11T14:29:59Z |
| publishDate | 2022-11-01 |
| publisher | SAGE Publishing |
| record_format | Article |
| series | Canadian Journal of Kidney Health and Disease |
| spelling | doaj.art-7dd46797f7e444718c599a6a92ef8b082022-12-22T04:18:40ZengSAGE PublishingCanadian Journal of Kidney Health and Disease2054-35812022-11-01910.1177/20543581221137180Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis PatientsNazanin Noori0Arti Sharma Parpia1Ron Wald2Marc B. Goldstein3Department of Medicine, McGill University, Montreal, Quebec, CanadaDivision of Nephrology, St. Michael’s Hospital, Toronto, Ontario, CanadaLi Ka Shing Knowledge Institute of St. Michael’s Hospital, Toronto, Ontario, CanadaDivision of Nephrology, St. Michael’s Hospital, Toronto, Ontario, CanadaBackground: Online dialysis clearance monitors typically provide an accurate value for Kt. A value for V (total body water [TBW]) is required to calculate Kt/V, the measure of the adequacy of the delivered dialysis in hemodialysis (HD) patients. Using bioimpedance spectroscopy (BIS), we previously developed 2 sex-specific equations for the estimation of the TBW, which we have chosen to name the St Michael’s Hospital (SMH) equations. Objective: The objective of this study was to validate the SMH equations in a second distinct population of patients. Design: Cross-sectional study. Setting: Single center hemodialysis unit at St Michael’s Hospital, a tertiary care teaching hospital, in Toronto, Canada. Patients: Eighty-one adult HD patients who had been receiving conventional maintenance HD for at least 3 months. Measurements: Anthropometric measurements including weight, height, and waist circumference were collected. TBW was measured by BIS using the Body Composition Monitor (Fresenius Medical Care, Bad Homburg, Germany). Methods: The Bland-Altman method to calculate the bias and limits of agreement and the difference plot analysis were used to evaluate the difference between the BIS-TBW and the TBW derived from our equations (SMH equation) in this validation cohort. Results: The TBW values based on our equations had a high correlation with BIS-TBW (correlation coefficients = 0.93, P values < .01, bias = 1.8 [95% CI: 1-2.6] liter). Application of SMH equations closely predicted Kt/V, based on BIS value, in all categories of waist circumference. Limitations: Small sample size, single-center, not including peritoneal dialysis patients. A larger and more heterogeneous sample with more patients at the extremes of body mass index would allow for more detailed sub-group analyses in different races and different anthropometric categories to better understand the performance of these equations in discrete sub-groups of patients. Conclusions: In maintenance HD patients, our previously derived equations to estimate the TBW using weight and waist circumference appear to be valid in a distinct patient population. Given the centrality of TBW to the calculation of small molecule clearance, the SMH equations may enhance the measurement of dialysis adequacy and inform practice.https://doi.org/10.1177/20543581221137180 |
| spellingShingle | Nazanin Noori Arti Sharma Parpia Ron Wald Marc B. Goldstein Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients Canadian Journal of Kidney Health and Disease |
| title | Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients |
| title_full | Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients |
| title_fullStr | Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients |
| title_full_unstemmed | Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients |
| title_short | Validation of the SMH Equations for the Estimation of the Total Body Water Volume in Hemodialysis Patients |
| title_sort | validation of the smh equations for the estimation of the total body water volume in hemodialysis patients |
| url | https://doi.org/10.1177/20543581221137180 |
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