Incidence, Recognition, and Follow-up of Laboratory Evidence of Acute Kidney Injury in Primary Care Practices: Analysis of 93,259 Creatinine Results

Background: Community-acquired acute kidney injury (CA-acute kidney injury) is under-recognized in the outpatient setting and is associated with adverse outcomes.

Methods: We analyzed the incidence of CA-acute kidney injury in an academic primary care practice and community health center and assessed recognition and follow-up as determined by repeat creatinine measurement (closed-loop). We reviewed 93,259 specimens for 36,593 unique patients from January 1, 2018, through December 31, 2021.

Results: There were 220 unique patients with CA-acute kidney injury, defined as a > 75% increase in creatinine from baseline (incidence: 150/100,000; 0.15% per year). One hundred thirty seven patients (62.3%) had repeat serum creatinine performed within 30 days. Chart reviews of the 83 (37.72%) patients with open loops found there was no follow-up creatinine ordered in 69/83 (83.1%) patients. Mean baseline creatinine was higher and estimated glomerular filtration rate (eGFR) was lower in the closed-loop group (0.92 ± 0.4 mg/dL; 84.45 ± 27.49 mL/min) vs the open-loop group (0.63 ± 0.34 mg/dL; 105.19 ± 26.67 mL/min) (P < .0001). Preexisting chronic kidney disease was more prevalent in closed-loop patients (35/137; 25.6%) compared with those with open loops (3/83; 3.6%). Patients with baseline chronic kidney disease were more likely to have closed loops. Progression to new chronic kidney disease was common among CA-acute kidney injury patients, occurring in 25% of open-loop and 24.1% of closed-loop patients. New baseline eGFR was lower in all groups.

Conclusions: Clinicians frequently overlooked a clinically significant change in eGFR, especially when the baseline creatinine and incident creatinine levels were in the "normal" range.