#1244 Rates of eGFR and UACR testing in patients with chronic kidney disease in England: Clinical Practice Research Datalink 2010-2019
Authors: Cockwell Paul , Du Chengan , Farmer Ruth , Popoola Remi , Muttram Louise , Zhang Ling , Shay Christina 
Published: May 2024

Abstract

Background and Aims
The NICE chronic kidney disease (CKD) treatment guidelines recommend regular laboratory measurements of both kidney function (eGFR) and damage (proteinuria) to appropriately inform efforts to prevent and treat progression of CKD. Recommendations also indicate frequency of such testing should increase with CKD progression. There are few data on rates of testing in patients with confirmed CKD with particularly paucity in patients with various stages of CKD.

Method
This non-interventional, observational study utilised data from primary care electronic health records from Clinical Practice Research Datalink (CPRD) AURUM. Patients aged ≥18 years with CKD registered in CPRD with at least one year of follow-up (FU) between January 1, 2010 and December 31, 2019 were identified. CKD was defined by an eGFR &lt;60 ml/min/1.73 m2 and/or presence of a uACR measurement ≥3 mg/mmol, both confirmed by a second measurement 90-365 days later (index). Patients with eGFR &lt;9 ml/min/1.73 m2 at index were excluded. Frequency of renal testing (eGFR and UACR) for each complete year of FU was quantified starting the day after index and patients were censored the last day of the final complete calendar year of FU after index. Frequency of renal testing per FU year was calculated overall and by CKD stage and level of albuminuria at index.

Results
In the 650 565 patients with CKD identified, mean age (SD) was 76.1 (11.3) years, 55.4% were female, and 88.5% White. Most (62.0%) patients had stage 3a CKD (eGFR 45-&lt;59 ml/min/1.73 m2) at index. Among patients with UACR measurements within 1 year prior to index (54.1%), 49.3% were A1 (&lt;3 mg/mmol), 43.4% A2 (3-30 mg/mmol) and 7.3% A3 (&gt;30 mg/mmol) at index. During the first year of FU, 81.45% of patients had 1+ eGFR test whereas 39.2% had 1+ UACR test. Patients more frequently received 1+ eGFR per year over subsequent years of FU but the low proportion with 1+ UACR test per year remained stable for UACR. The mean (SD) number of eGFR and UACR tests performed per patient in the first year of FU was 2.09 (2.39) and 0.49 (0.70), respectively. More frequent eGFR testing was observed with lower eGFR at index and across subsequent years of FU. Frequency of UACR testing was lower at more advanced stages of CKD at index in all FU years, however, no trends in UACR testing frequency were observed by level of albuminuria at index.

Conclusion
This evidence from a population-based sample of patients with confirmed CKD in England, indicates that eGFR is being monitored in the majority of patients, yet UACR testing is suboptimal according to NICE guidelines regardless of level of kidney function or level of albuminuria. Although eGFR testing is more frequent at more advanced stages of CKD, UACR testing seems to become less frequent with more advanced stages of CKD. With emergence of new therapies to prevent progression of CKD, efforts to increase frequency of UACR testing are needed (particularly in earlier CKD stages) to ensure that patients who are at risk of worsening CKD and albuminuria receive appropriate management.