Muscle weakness, pain, and fatigue impair daily function in chronic kidney disease: a cross-sectional analysis from the I-RACE study

Muscle dysfunction symptoms such as weakness and cramps are common in people with chronic kidney disease (CKD), but their impact on activities of daily living (ADLs) is not well understood. This study explored the association between muscle symptoms and patient-reported ADL impact in individuals with and without CKD. This cross-sectional secondary analysis of the I-RACE study (ISRCTN11596292) included adults (≥18 years) across the CKD spectrum and adults without CKD. Participants completed a bespoke Muscle Symptoms Scale assessing muscle-related symptoms and their impact on ADLs (daily activities, socializing, working, exercising). Group differences were tested using univariate general linear models; associations were examined via linear regression. Among 1048 participants (304 non-CKD, 345 non-dialysis CKD, 281 dialysis, 118 transplant), mean age was 57 ± 17 years and 51% were female. Muscle symptoms (weakness, tiredness, aches/pains, cramps/tightness, reduced muscle size, restless legs) were significantly worse in CKD groups (all p < 0.05). Dialysis and transplant recipients reported more severe symptoms than non-dialysis CKD, with dialysis patients reporting the worst weakness and muscle size reduction. ADL impact followed a similar pattern, with dialysis patients most affected. All muscle symptoms were significantly associated with ADL impact in CKD, particularly weakness and reduced muscle size (all p < 0.05). Muscle dysfunction symptoms are more severe in CKD, especially in kidney failure. These symptoms are strongly associated with impaired ADLs, highlighting muscle size and strength as potential targets for intervention through exercise.