Are mid-dialysis handgrip strength measurements reliable and reproducible? A comparison to pre-dialysis handgrip strength measurements.

Objective: Handgrip strength (HGS) is an important predictor of nutritional status. Current guidelines recommend measurement of HGS pre-dialysis; however, this may be impractical and measurement often occurs during haemodialysis (HD). This study aims to determine the reliability, reproducibility and agreement of HGS values pre- and mid-dialysis.

Design: Participants were recruited from four Australian HD units (n=48). Eligible participants were stable on HD for at least 3 months and not acutely unwell. HGS was measured in triplicate on the non-fistula arm before dialysis and two hours into dialysis for three consecutive weeks. Nutritional status and frailty were assessed via subjective global assessment and the FRAIL Questionnaire, respectively. Bland Altman plots were used to determine agreement between pre- and mid-dialysis measures. Linear mixed models were used to determine differences between pre- and mid-dialysis values controlling for confounders.

Results: HGS measures were statistically but not clinically greater pre-dialysis compared to mid-dialysis (19.7±12.9 vs 18.8±13.6 kg, p=0.0433, mean difference 0.5kg). Bland Altman plots demonstrated an acceptable level of agreement between pre- and mid-dialysis HGS measures, suggesting no systematic bias in HGS. The influence of confounders (gender, age, dialysis vintage, frailty status, nutritional status, UF rate, degree of fluid overload, diabetes, PVD and weight) on the differences between pre- and mid-dialysis measures were not statistically significant.

Conclusion: This study found HGS taken either pre- or mid-dialysis were reliable and reproducible. Given the agreement between pre- and mid-dialysis HGS measures, HGS measured mid-dialysis may be used for nutritional assessment of HD patients.