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

Low Skeletal Muscle Mass and Clinical Outcomes in Chronic Obstructive Pulmonary Disease

BACKGROUND

In patients with chronic obstructive pulmonary disease (COPD), decreased muscle mass is a frequently encountered comorbidity in clinical practice. However, the evaluation of muscle mass in patients with COPD in real-world practice is rare.

METHODS

We retrospectively reviewed the electronic medical records of all patients with COPD who underwent bioelectrical impedance analysis at least once between January 2011 and December 2021 in three hospitals. Then, we analyzed the performance rate of muscle mass measurement in the patients and the correlation between muscle mass, clinical parameters, and COPD prognosis.

RESULTS

Among the 24,502 patients with COPD, only 270 (1.1%) underwent muscle mass measurements. The total skeletal muscle mass index was significantly correlated with albumin, alanine transaminase, and creatinine to cystatin C ratio in patients with COPD (r=0.1614, p=0.011; r=0.2112, p=0.001; and r=0.3671, p=0.001, respectively). Acute exacerbation of COPD (AE COPD) was significantly correlated with muscle mass, especially the truncal skeletal muscle mass index (TSMI) in males (r=-0.196, p=0.007). In the multivariate analysis, TSMI and cystatin C were significant risk factors for AE COPD (hazard ratio, 0.200 [95% confidence interval, CI, 0.048 to 0.838] and 4.990 [95% CI, 1.070 to 23.278], respectively).

CONCLUSION

Low muscle mass negatively affects the clinical outcomes in patients with COPD. Despite its clinical significance, muscle mass measurement is performed in a small proportion of patients with COPD. Therefore, protocols and guidelines for the screening of sarcopenia in patients with COPD should be established.

Correlation of TNF-α, Cys C, and NLRP3 inflammasomes with venous ulcers in patients with lower extremity varicose veins

OBJECTIVE

To explore the correlation of tumor necrosis factor α (TNF-α), cystatin C (Cys C), and NLR family pyrin domain containing 3 (NLRP3) inflammasomes with venous ulcers from lower extremity varicose veins.

METHODS

In this retrospective analysis, 135 patients with primary varicose veins of lower extremities were selected and divided into a varicose ulcer group (n=32) and a non-varicose ulcer group (n=103) according to clinical ulcer presence. Healthy adults with similar general information during the same period were included as a healthy controls (n=30). The levels of TNF-α, interleukin-1β (IL-1β), Cys C, and NLRP3 inflammasomes were statistically analyzed among the three groups. Logistic regression was used for analyzing the risk factors for venous ulcers in patients with varicose veins of the lower extremities. Spearman correlation was applied for correlation analysis. The area under the receiver operating characteristic (ROC) curve (AUC) was found to disclose the predictive value of TNF-α, Cys C, and NLRP3 inflammasomes for venous ulcers.

RESULTS

(1) Logistic regression analysis showed that TNF-α, IL-1β, and NLRP3 inflammasomes were risk factors for venous ulcers in patients with varicose veins of the lower extremity, and Cys C in ulcer wound tissue was a protective factor. (2) TNF-α was significantly correlated with IL-1β and Cys C in ulcer wound tissue, and NLRP3 in plasma (r=0.256, -0.290, 0.305; P=0.003, 0.001, <0.001). IL-1β was significantly correlated with CysC in ulcer wound tissue and plasma (r=-0.251, -0.193; P=0.003, 0.025). (3) The AUC, sensitivity, and specificity of TNF-α and NLRP3 inflammasomes for predicting varicose veins were high, with AUC of 0.881 and 0.712, sensitivity of 0.875% and 0.875%, and specificity of 0.893% and 0.738%, respectively.

CONCLUSION

TNF-α in plasma, Cys C in ulcer wound tissue and plasma, and NLRP3 inflammasomes in plasma were closely related to the occurrence of venous ulcers in patients with varicose veins of the lower and may serve as new targets for treatment.

Association Between Serum Cystatin C and Thyroid Diseases: A Systematic Review and Meta-Analysis

Background

Cystatin C (CysC) is often used to diagnose and monitor renal diseases. Although some studies have investigated the association between serum CysC levels and thyroid diseases, their reported results were inconsistent. Therefore, the relationship between CysC levels and thyroid diseases remains controversial.

Aim

This meta-analysis aimed to statistically evaluate serum CysC levels in patients with thyroid diseases.

Methods

A literature search was conducted using the PubMed, Web of Science, Embase, EBSCO, and Wiley Online Library databases. The following search terms were used for the title or abstract: "Cystatin C" or "CysC" in combination with the terms "thyroid disease", "thyroid function", "hypothyroidism", or "hyperthyroidism". The results of the systematic analysis were presented as standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs).

Results

Eleven articles (1,265 cases and 894 controls) were included in the meta-analysis. The results of the meta-analysis showed that the serum CysC levels of patients with hyperthyroidism were significantly higher than those of the controls (SMD: 1.79, 95% CI [1.34, 2.25]), and the serum CysC levels of patients with hypothyroidism were significantly lower than those of the controls (SMD -0.59, 95% CI [-0.82, -0.36]). Moreover, the treatment of thyroid diseases significantly affected serum CysC levels.

Conclusions

To the best of our knowledge, this meta-analysis is the first to evaluate serum CysC levels in patients with thyroid diseases. Our findings suggest that thyroid function affects serum CysC levels and that serum CysC may be an effective marker for monitoring thyroid diseases.

Systematic Review Registration

PROSPERO [https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=258022], identifier CRD42021258022].

Performance and Determinants of Serum Creatinine and Cystatin C-Based GFR Estimating Equations in South Asians

INTRODUCTION

The creatinine-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (eGFR) equation was calibrated for the general Pakistan population (eGFRcr-PK) to eliminate bias and improve accuracy. Cystatin C-based CKD-EPI equations (eGFRcys and eGFRcr-cys) have not been assessed in this population, and non-GFR determinants of cystatin C are unknown.

METHODS

We assessed eGFRcys, eGFRcr-cys, and non-GFR determinants of cystatin C in a cross-sectional study of 557 participants (≥40 years of age) from Pakistan. We compared bias (median difference in measured GFR [mGFR] and eGFR), precision (interquartile range [IQR] of differences), accuracy (percentage of eGFR within 30% of mGFR), root mean square error (RMSE), and classification of mGFR <60 ml/min/1.73 m2 (area under the receiver operating characteristic curve [AUC] and net reclassification index [NRI]) among eGFR equations.

RESULTS

We found that eGFRcys underestimated mGFR (bias, 12.7 ml/min/1.73 m2 [95% confidence interval {CI} 10.7-15.2]). eGFRcr-cys did not improve performance over eGFRcr-PK in precision (P = 0.52), accuracy (P = 0.58), or RMSE (P = 0.49). Results were consistent among subgroups by age, sex, smoking, body mass index (BMI), and eGFR. NRI was 7.31% (95% CI 1.52%-13.1%; P < 0.001) for eGFRcr-cys versus eGFRcr-PK, but AUC was not improved (0.92 [95% CI 0.87-0.96] vs. 0.90 [95% CI 0.86-0.95]; P = 0.056). Non-GFR determinants of higher cystatin C included male sex, smoking, higher BMI and total body fat, and lower lean body mass.

CONCLUSION

eGFRcys underestimated mGFR in South Asians and eGFRcr-cys did not offer substantial advantage compared with eGFRcr-PK. Future studies are warranted to better understand the large bias in eGFRcys and non-GFR determinants of cystatin C in South Asians.