A Reliability and Criterion-Related Validity Study of Bioelectric Impedance Analysis (BIA)
The problem. The purpose of this study was to determine the reliability and criterion-related validity of bioelectrical impedance analysis (BIA) as a method of monitoring fluid changes in congestive heart failure (CHF) patients undergoing diuresis. Procedure. Thirty hospitalized CHF patients undergoing diuresis were measured with BIA and weighed prior to the administration of a diuretic and 24 hours thereafter. An intake-output (I-0) record was obtained during this time period. Daily body weights (BWT) and I-0 records served as the criteria by which to compare the BIA measurements. A reliability coefficient on 10 normal age-matched subjects was obtained using a test-retest approach. Findings. Statistically significant relationships were found between BIA total body water (TBW) and BWT, r = .729 (p<.001) and BIA-TBW and I-0, r = .745 (p<.001) when the average of right and left TBWs was obtained. The BIA-TBW taken from the non-dominant side of the body also resulted in strong correlations with BWT and I-0, r = .648 (p<.001), r = .704 (p<.001) respectively. The BIA-TBW taken from the dominant side correlated well with BWT, r = .515 (p = .001), but did not correlate significantly with I-0, r = .451 (p = .024). A reliability coefficient of .9984 was obtained. Conclusions. The results of this study indicate that BIA is a reliable technique and comparable to the traditional methods of DBW and I-0 in fluid assessment of CHF patients undergoing diuresis. Recommendations. Repeating the study with the inclusion of reliability and validity determinations of the criteria standards will improve the integrity of the study. In addition, further refinement of BIA technology identifying hydration abnormalities and using the average of right and left BIA-TBWs will result in more accurate data in patient populations.
Impedance, Bioelectric--Validity, Impedance, Bioelectric--Reliability, Impedance, Bioelectric--Analysis
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