The Ratio Serum Creatinine/Serum Cystatin C (a Surrogate Marker of Muscle Mass) as a Predictor of Hospitalization in Chronic Obstructive Pulmonary Disease Outpatients

Abstract

Background: In chronic obstructive pulmonary disease (COPD), low muscle mass has been associated with several clinical outcomes such as low exercise capacity, hospital admission, and mortality. The Sarcopenia Index (SI) is a novel way to estimate muscle mass based on the ratio of serum creatinine (produced exclusively by muscle)/cystatin C (produced by all nucleated body cells). Objectives: This study aims to assess the SI in stable COPD outpatients, as compared with a healthy control group, to quantify its relationship with several important clinical features in COPD, and to study its potential usefulness to predict COPD exacerbations and hospital admissions. Methods: The SI was calculated in 18 healthy control subjects and 65 stable COPD outpatients were included in the study. Patients were prospectively followed for 1 year after being enrolled in the study. Results: COPD patients had a lower SI than controls, that is lower muscle mass. Furthermore, patients with a modified Medical Research Council dyspnea score ≥2, patients with a COPD Assessment Test score ≥10, and patients with a high risk of exacerbation had lower levels of SI compared with patients without these characteristics. SI correlated with FEV1 (r = 0.491, p < 0.001), the 6-min walking test (r = 0.560, p = 0.001), and the Fat-Free Mass Index (r = 0.431, p = 0.017). Univariate and multivariate Cox proportional risk analysis showed that a low SI is an independent predictor of hospital admission in COPD outpatients followed for 1 year (HR 5.16, p = 0.025). Conclusions: The ratio serum creatinine/serum cystatin C correlates with several COPD characteristics, and it can be used to predict COPD hospitalization.

Towards Personalized Management of Sarcopenia in COPD

“…69 Since Cr reflects muscle mass and CysC does not, the Cr/CysC ratio has been proposed as a surrogate marker for sarcopenia. A correlation between Cr/CysC ratio with muscle mass 69 and adverse COPD-related outcomes 70 has been demonstrated. Moreover, Hirai et al 71 demonstrated that the Cr/CysC may serve as a surrogate marker for sarcopenia in COPD, with a cut-off of 0.71 in male patients.…”

The association between cystatin C and COPD: a meta-analysis and systematic review

“…Abbreviations: CI, confidence interval; FEV1%pre, forced expiratory volume in 1 second as percentage of predicted volume; FEV1/FVC, forced expiratory volume in 1 s/forced vital capacity studies might be impacted by confounding factors, which might have an impact on our results. Fifth, the probability of death due to COPD is much higher in Asian, particularly China, than western countries [55,56], and Caucasians with COPD have lower serum Cys C level compared with Asians COPD patients [28,30,38,42]. Although we had done a review of the available published studies, most studies included were from Asia, therefore the promotion of conclusions had some limitations.…”

“…Recent studies indicate a possible link between Cys C and COPD [24][25][26][27][28]; however, the conclusion is not clear. Most studies have shown that serum Cys C levels are higher in the exacerbation group than stable COPD or healthy control [29,30], but Selder et al [31] find that serum Cys C levels are lower in exacerbation group than stable COPD.…”

Creatinine-to-cystatin C ratio as a marker of skeletal muscle mass for predicting postoperative complications in patients undergoing gastric cancer surgery

“…Some studies have supported that the Scr/CysC ratio (CCR) may serve as a biomarker of skeletal muscle mass. These results indicate that the CCR is a simple and inexpensive measure that can be used to evaluate the skeletal muscle mass of patients with malignancies, such as gastric cancer (12)(13)(14)(15)(16). However, whether this ratio can be regarded as a predictive marker of postoperative complications in gastric cancer patients has not been reported.…”