Assessment of functional capacity in children with chronic kidney disease using various field tests

BACKGROUND: Children with chronic kidney disease (CKD) often have a reduced functional capacity. The study aimed to evaluate the functional capacity of children with CKD by using three field tests: 6 min walk (6MWT), 2 min walk (2MWT), and 3 min step test (3MST), and investigate relationships between these tests and to determine which tests patients prefer. METHODS: This study evaluated 51 children with CKD (19 female, 32 male). The 6MWT, 2MWT, and 3MST were used to measure functional capacity. After performing the tests, participants reported their preferred one. Quadriceps muscle strength (QMS) and hand grip strength (HGS) were assessed using dynamometers. RESULTS: The mean age of the patients was 13.7 ± 3.2 years. A total of 22 patients (43.1%) were in stage 2 CKD, 13 patients (25.5%) in stage 3, six patients (11.8%) in stage 4, two patients (3.9%) in stage 5 non-dialysis (3.9%) and eight patients (15.7%) in stage 5 on dialysis. No statistically significant differences were observed between the early and advanced CKD groups for any of the field tests (p > 0.05). However, the early CKD group had a significantly higher dominant QMS than the advanced CKD group (p = 0.023). Most children preferred walking tests (6MWT: 43.1%; 2MWT: 43.1%), while 13.8% preferred the 3MST. Moderate positive correlations were found between 6 and 2MWT (r = 0.669, p < 0.001) and between 6MWT and 3MST (r = 0.422, p = 0.002). CONCLUSIONS: Peripheral muscle strength was deteriorated in advanced CKD. The 2MWT is a practical and time-efficient alternative to the 6MWT. The 3MST remains a viable option when walking tests are not feasible. TRIAL REGISTRATION: NCT06683339.