The association of muscle size, strength and exercise capacity with all-cause mortality in non-dialysis-dependent CKD patients.

Abstract

Patients with chronic kidney disease (CKD) are commonly reported to exhibit skeletal muscle wasting, reduced strength and exercise capacity. Evidence from patients with end-stage renal disease (ESRD) demonstrates these factors are associated with mortality, but it is unclear whether this relationship exists earlier in the illness. Our objective was to determine whether muscle size, strength or exercise capacity was associated with all-cause mortality, unscheduled hospital admissions or time to ESRD in patients not requiring dialysis. This is a prospective cohort study of 89 patients with CKD stages 3b-5 not requiring renal replacement therapy with a mean follow-up period of 3.3years in which the contribution of predictors of rectus femoris muscle size, muscle strength, exercise capacity to all-cause mortality rates, progression to ESRD and time to first hospitalization were investigated. Unadjusted analysis suggested each 1cm2 increase in quadriceps muscle size (measured by ultrasonography cross-sectional area) was associated with a 38% reduced risk for death (p=.006), and a 10m improvement on the incremental shuttle walk test was associated with a 3% reduced risk for death (p=.04). However, this relationship was not present in analysis adjusted for age, gender and eGFR. No association was seen between any factor for the development of ESRD or time to first hospitalization. These results suggest that in this small cohort, muscle size and exercise capacity are associated with mortality when considered alone, but this relationship was not present in adjusted analyses. Further investigation in a larger patient group is warranted.