The association of physical function and physical activity with all-cause mortality and adverse clinical outcomes in nondialysis chronic kidney disease: a systematic review.

Objective: People with nondialysis-dependent chronic kidney disease (CKD) and renal transplant recipients (RTRs) have compromised physical function and reduced physical activity (PA) levels. Whilst established in healthy older adults and other chronic diseases, this association remains underexplored in CKD. We aimed to review the existing research investigating poor physical function and PA with clinical outcome in nondialysis CKD.

Data sources: Electronic databases (PubMed, MEDLINE, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials) were searched until December 2017 for cohort studies reporting objective or subjective measures of PA and physical function and the associations with adverse clinical outcomes and all-cause mortality in patients with nondialysis CKD stages 1-5 and RTRs. The protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42016039060).

Review methods: Study quality was assessed using the Newcastle-Ottawa Scale and the Agency for Healthcare and Research Quality (AHRQ) standards.

Results: A total of 29 studies were included; 12 reporting on physical function and 17 on PA. Only eight studies were conducted with RTRs. The majority were classified as 'good' according to the AHRQ standards. Although not appropriate for meta-analysis due to variance in the outcome measures reported, a coherent pattern was seen with higher mortality rates or prevalence of adverse clinical events associated with lower PA and physical function levels, irrespective of the measurement tool used. Sources of bias included incomplete description of participant flow through the study and over reliance on self-report measures.

Conclusions: In nondialysis CKD, survival rates correlate with greater PA and physical function levels. Further trials are required to investigate causality and the effectiveness of physical function and PA interventions in improving outcomes. Future work should identify standard assessment protocols for PA and physical function.