Standardized Method to Measure Muscle Force at the Bedside in Hemodialysis Patients.

OBJECTIVES: In hemodialysis, diminution of muscle strength constitutes a major prognostic factor of mortality. Currently, measurement of quadriceps isometric maximal voluntary force (MVF) represents the reference method to investigate muscle strength. However, reduction of MVF is rarely detected in these patients due to the absence of portative bedside tools in clinical practice. The purposes of this study were therefore to assess the agreement of a belt-stabilized handheld dynamometer (HHD) with the dynamometer chair (reference method) and to determine intratester and intertester reliability of the quadriceps MVF measurements using belt-stabilized HHD in healthy subjects and in hemodialysis patients.

DESIGN: Repeated-measures cross-sectional study.

SETTING: Clinical and academic hospital.

PARTICIPANTS: Fifty-three healthy adult subjects (23 males, 36.5 + 12.5 y.o.) and 21 hemodialysis patients (14 males, 72.4 + 13.3 y.o., dialysis vintage 30 + 75.1 months).

INTERVENTION: Not applicable.

MAIN OUTCOME MEASURE: MVF measurements were assessed with belt-stabilized HHD and dynamometer chair, by two independent investigators. The agreement between the two devices would be quantified using the Bland-Altman 95% limits of agreement (LOA) method and the Spearman correlation.

RESULTS: For healthy subjects and hemodialysis patients, Spearman coefficients between belt-stabilized HHD and dynamometer chair were 0.63 and 0.75, respectively (P < .05). In hemodialysis group, reliability was excellent for both the intratester and intertester reliability R2  = 0.85 (P < .01) and R2  = 0.90 (P < .01), respectively. In all individuals, the mean difference between the dynamometer chair and the belt-stabilized HHD was -13.07 ± 21.77 N.m. (P < .001). The LOA for the upper and the lower was 29.59 and -55.73 N.m., respectively.

CONCLUSION: In healthy subjects and in hemodialysis patients, the belt-stabilized HHD dynamometer appears as a valid and reliable method to measure in clinical practice isometric MVF of quadriceps in hemodialysis patients. Therefore, the belt-stabilized HHD appears as a suitable and a relevant diagnostic tool for the identification of muscle dysfunction in hemodialysis patients.