Diamantidis CJ, et al. - In order to assess the extent of under-recognition of Chronic kidney disease (CKD) diagnosis among Medicare beneficiaries, researchers assessed claims-based diagnosis and lab data and examined patient factors associated with clinically recognized CKD. and investigated CKD stage concordance between claims- and lab-based sources in a cohort of Medicare beneficiaries. Lab-based CKD was recognized among 206,036 beneficiaries; of these, only 11.8% (n = 24,286) had clinically recognized CKD via diagnoses. Beneficiaries who had higher CKD stages, were non-elderly, were Hispanic or non-Hispanic Black, lived in core metropolitan areas, had multiple chronic conditions or outpatient visits in 2010, or saw a nephrologist, more frequently had clinical recognition. In the subset of 18,749 beneficiaries with CKD stage identified from both labs and diagnoses, concordant CKD stage was reported in 70.0%. This was more frequently observed among beneficiaries who were older adults, male, lived in micropolitan areas instead of non-core areas, or saw a nephrologist. These findings suggest that Medicare fee-for-service beneficiaries have a significant under-diagnosis of CKD, which can be addressed with the availability of lab results.