Danforth KN, et al. - Researchers performed this mixed-methods study investigating the risk factors, facilitators, and barriers to timely follow-up of an abnormal estimated glomerular filtration rate (eGFR) for the diagnosis of chronic kidney disease. At a large integrated health care delivery system, 244,540 patients (21 years or older) with incident abnormal eGFRs underwent quantitative analyses ordered by 7,164 providers. Fifteen physician interviews comprised qualitative analyses. They defined timely follow-up of incident abnormal eGFRs as repeat eGFR obtained within 60 to 150 days, follow-up testing before 60 days that indicated normal kidney function, or diagnosis before 60 days of chronic kidney disease or kidney cancer. Timely follow-up of the incident abnormal eGFRs was lacking (ie, a care gap) in 58% of patients. Findings suggest that in an electronic health record (EHR)-based integrated health care delivery system, timely follow-up of abnormal results remains challenging. Test follow-up could be improved via approaches improving provider EHR message box management and leveraging health information technology (eg, flagging abnormal eGFR results), making organizational/staffing changes (eg, increasing the role of nurses in managing laboratory results), and boosting patient engagement through better patient portals.