Making the case for standardized outcome measures in exercise and physical activity research in chronic kidney disease

Physical activity and exercise are core components of lifestyle modification strategies for the management of chronic kidney disease (CKD). Yet, physical activity levels have consistently remained poor across all stages of CKD. Exercise interventions, including aerobic and resistance training, and lifestyle interventions promoting physical activity, have been shown to improve a multitude of clinical endpoints and factors important to patients; however, despite the evidence, the provision of physical activity in clinical practice is still inadequate. The usefulness of any study hinges on the adequacy and clinical relevance of the outcomes and outcome measures used. Inconsistent reporting and wide disparities in outcome use across studies limit evidence synthesis to help guide clinical practice. The kidney exercise and physical activity field has been particularly prone to inconsistent outcome reporting. To ensure research is relevant and able to influence clinical practice and future research, we need to ensure the use (and reporting) of standardized, relevant outcome measures. Core outcome sets (COS) have been widely developed across many chronic conditions, yet these COS have not been tailored to physical activity and exercise in CKD. Outcomes in clinical research need to be relevant to the intervention being employed. From this perspective, we summarize the importance that standardizing outcomes and outcome measures may have in relation to physical activity and exercise interventions for people living with kidney disease.