Objectives To externally validate the 4-variable Kidney Failure Risk Equation (KFRE) in the Peruvian population for predicting kidney failure at 2 and 5 years.

Design A retrospective cohort study.

Setting 17 primary care centers from the Health’s Social Security of Peru.

Participants Patients older than 18 years, diagnosed with chronic kidney disease (CKD) stage 3a-3b-4 and 3b-4, between January 2013 and December 2017. Patients were followed until they developed kidney failure, died, were lost, or ended the study (December 31, 2019), whichever came first.

Primary and Secondary Outcome Measures Performance of the KFRE model was assessed based on discrimination and calibration measures considering the competing risk of death.

Results We included 7519 patients in stages 3a-4 and 2,798 patients in stages 3b-4. The estimated cumulative incidence of kidney failure, accounting for competing event of death, at two years and five years was 1.52% and 3.37% in stages 3a-4 and 3.15% and 6.86% in stages 3b-4. KFRE discrimination at 2 and 5 years was high, with Time-Dependent Area Under the Curve (AUC-td) and C-index > 0.8 for all populations. Regarding calibration in-the-large, the Observed-to-Expected (O/E) ratio and the calibration intercept indicated that KFRE underestimates the overall risk at two years and overestimates it at 5-years in all populations.

Conclusions The 4-variable KFRE models have good discrimination but poor calibration in the Peruvian population. The model underestimates the risk of kidney failure in the short term and overestimates it in the long term. Further research should focus on updating or recalibrating the KFRE model to better predict kidney failure in the Peruvian context before recommending its use in clinical practice.

What is already known on this topic

The Kidney Failure Risk Equation (KFRE) has been externally validated in several independent studies worldwide.

Most of these validations have been conducted in North American, European, and Asian countries.

There is a notable gap in the literature regarding KFRE validation studies in Latin America, particularly at the primary care level.

What this study adds

This study validates the 4-variable KFRE in Peruvian CKD patients, demonstrating good discrimination whilst emphasising the need for recalibration to prevent detrimental patient outcomes.

Future research should ensure model recalibration, evaluate KFRE’s clinical utility, and investigate broader external validation in diverse populations prior to its implementation in clinical practice.

JBZ and RCG are full-time employees of EsSalud, and PSB has received consultancy fees from EsSalud. However, the authors affirm that their respective affiliations with EsSalud have not influenced any aspect of the study, including study design, data collection, analysis, interpretation, or manuscript preparation. The authors declare that there are no other competing interests or potential conflicts of interest related to the content of this manuscript.

This study was entirely self-funded by the authors and did not receive any external financial support.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Research Ethics Committee of the Edgardo Rebagliati National Hospital approved this study (575-GRPR-ESSALUD-2021). Because all the data from clinical registries were anonymized before being processed for the research, the ethics committee accepted the waiver of informed consent from the patients.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

The analysis code essential for the replication of study findings can be accessed at this link: https://github.com/psotob91/kfre-ckd-reba-peru. As per the privacy policies of EsSalud, the minimal data set is not open to public access. However, we are amenable to providing the anonymised data upon receipt of a reasonable request directed to the corresponding author (percys1991gmail.com).