Low creatinine-cystatin C ratio a red flag for muscle volume, gait speed

Among middle-aged women, low creatinine-cystatin C ratio is predictive of reduced fat-free muscle volumes and poorer gait speeds after more than 6 years, as shown in a study.

The study included 891 participants (mean age at baseline 56.2 years) from the Integrated Women's Health Programme (IWHP) cohort who underwent objective muscle strength and physical performance assessments and MRI during the baseline and follow-up visits.

Creatinine to cystatin C ratio was calculated, and a ratio of less than 8.16 was used to define a low creatinine to cystatin C ratio. Multivariable regression analyses were used to estimate the associations between baseline creatinine to cystatin C ratio with muscle volumes and function 6.6 years later.

A low creatinine to cystatin C ratio at baseline correlated with lower MRI-measured muscle volumes and poorer physical function 6.6 years later. Fat-free thigh muscle volume was lower by a mean of 0.350 L (95 percent confidence interval [CI], 0.183–0.518) in participants with low vs high creatinine to cystatin C ratio.

In terms of gait, usual gait speed was slower by a mean of 0.029 m/s (95 percent CI, 0.006–0.053) and narrow gait speed was slower by a mean of 0.049 m/s (95 percent CI, 0.020–0.078) in participants with low vs high creatinine to cystatin C ratio.

No association was observed for handgrip strength and repeated chair stands and one-leg stand tests.

The findings warrant additional research to establish the utility of creatinine to cystatin C ratio as a predictive biomarker for adverse events related to sarcopenia in midlife women.