Test–retest reliability, validation, and “minimal detectable change” scores for frequently reported tests of objective physical function in patients with non-dialysis chronic kidney disease

Abstract

Physical function is an important outcome in chronic kidney disease (CKD). We aimed to establish the reliability, validity, and the "minimal detectable change" (MDC) of several common tests used in renal rehabilitation and research. In a repeated measures design, 41 patients with CKD not requiring dialysis (stage 3b to 5) were assessed at an interval of 6 weeks. The tests were the incremental shuttle walk test (ISWT), "sit-to-stand" (STS) test, estimated 1 repetition maximum for quadriceps strength (e1RM), and VO by cardiopulmonary exercise testing (CPET). Reliability was assessed using intraclass correlation coefficient and Bland-Altman analysis, and absolute reliability by standard error of measurement and MDC. The ISWT, STS-60, e1RM, and CPET had "good" to "excellent" reliability (0.973, 0.927, 0.927, and 0.866), respectively. STS-5 reliability was poor (0.676). The MDC is ISWT, 20 m; STS-5, 7.5 s; STS-60, 4 reps; e1RM, 6.4 kg; VO, 2.8 ml/kg/min. There was strong correlation between the ISWT and VO (r = 0.73 and 0.74). While there was poor correlation between the STS-5 and e1RM (r = 0.14 and 0.47), better correlation was seen between STS-5 and ISWT (r = 0.55 and 0.74). In conclusion, the ISWT, STS-60, e1RM, and CPET are reliable tests of function in CKD. The ISWT is a valid means of exercise capacity. The MDC can help researchers and rehabilitation professionals interpret changes following an intervention.

Feasibility and effectiveness of pre‐emptive rehabilitation in persons approaching dialysis (PREHAB)

“…The 10-week combined cardiovascular and resistance exercise intervention appears to have led to improved exercise capacity and physical functioning, which is consistent with previous findings, where exercise intervention had a positive impact upon physical function and exercise capacity (Greenwood et al 2012;da Silva et al 2013;Watson et al 2015). Wilkinson et al (2018) reported the minimal detectable change (MDC) for the ISWT to be 20 m, and in our study we observed an increase of 55 m, indicating a 'true' increase in ISWT. This was not observed for quadriceps SRM or STS 60 however, with observed increases below the MDC of 6.4 kg for quadriceps SRM and four repetitions for STS 60.…”

“…Wilkinson et al . () reported the minimal detectable change (MDC) for the ISWT to be 20 m, and in our study we observed an increase of 55 m, indicating a ‘true’ increase in ISWT. This was not observed for quadriceps SRM or STS 60 however, with observed increases below the MDC of 6.4 kg for quadriceps SRM and four repetitions for STS 60.…”

Diagnostic Accuracy of Frailty Screening Methods in Advanced Chronic Kidney Disease

“…Finally, the frailty screening methods used in our study were only performed at 1 time point and therefore we cannot report their reliability. Other studies have reported the reliability of physical assessment measures, though the reliability of the Clinical Frailty Scale and PRISMA-7 have not been assessed in an advanced CKD cohort to our knowledge [58][59][60].…”

Test–Retest Reliability for Physical Function Measures in Patients with Chronic Kidney Disease

“…They also reported a lower MDC of 20 m in the ISWT compared to the current study that found 74.81 m of MDC 90 in the pre‐dialysis group (Wilkinson et al . ). The dialysis group of the current study revealed an even higher variability with MDC 90 of 110.27 m and an ICC value of 0.80.…”