CST3 and chronic obstructive pulmonary disease: For instance, one case-control study reported a significant CKD prevalence in COPD compared to non-COPD groups; (31% vs 8% p < 0.001) based on estimated glomerular filtration rate (eGFRCr), and (53% vs 15% p < 0.001) based on estimated cystatin C levels (eGFRCys).