Middle-aged and older adults with high serum creatinine to cystatin C ratio are more likely to have a slow annual decline in PEF and PEF% pred, according to a study published in the May 2023 issue of the journal Respiratory Medicine.

For this study, the researchers utilised data from the China Health and Retirement Longitudinal Study (CHARLS) for which the baseline data of Chinese residents aged ≥45 years was collected in 2011 with follow-up every two years. Data for the present study was obtained from the 2011 baseline survey and follow-up in 2015. Serum creatinine and cystatin C levels were measured at baseline, while assessment of the pulmonary function with peak expiratory flow (PEF) was done in 2011 and 2015. Their aim was to analyse the cross-sectional association between serum creatinine to cystatin C ratio (CCR) and PEF and the longitudinal association between CCR and annual decline in PEF. CCR is a surrogate marker for muscle wasting.

A total of 5812 individuals were recruited in 2011 for cross-sectional analysis with women comprising half of the study group and 4164 were followed up in 2015. Analysis revealed a positive association between serum CCR and PEF and PEF% pred. Every one standard deviation increase in CCR was associated with increases in PEF of 41.55 L/min and increase in PEF% pred of 10.77%. On longitudinal analysis, higher CCR level at baseline was linked to gradual decrease in PEF and PEF% pred annually. This association was found to be significant only in women and those who were never smokers.

This study has shown that older adults, especially never smokers and women, with high serum creatinine to cystatin C ratio are at a lower risk of airflow limitation. These findings suggest CCR as a potential marker to watch and predict reduction in lung function in middle-aged and older adults.

Reference

1. Wang K, et al. The creatinine-to-cystatin C ratio (a surrogate marker of muscle mass) as a predictor of lung function decline in older adults: A nationwide longitudinal study in China. Respir Med. 2023 May;211:107197. doi: 10.1016/j.rmed.2023.107197.