MO449VALIDATION OF MAYO CLINIC CLASSIFICATION AS A PREDICTOR OF FUTURE RENAL FUNCTION IMPAIRMENT IN PATIENTS WITH AUTOSOMAL POLYCYSTIC KIDNEY DISEASE (ADPKD) IN A POPULATION IN THE SOUTH OF SPAIN
Authors: Borrego-Utiel Francisco-Jose , Esteban de la Rosa Rafael Jose , Merino Garcia Enoc , Polo Moyano Aurora , Moriana Dominguez Clara , Morales García Ana Isabel , Bravo Soto Juan Antonio 
Published: May 2021

Abstract

Background and Aims
The Mayo Clinic classification (MCC) is used in patients with ADPKD to identify those who may experience a more rapid deterioration of glomerular filtration rate (GFR). It has been developed in the American population but has not been validated in other populations. Our objective was to analyze whether the CCM predictive model is valid in an ADPKD population from southern Spain and whether it can identify populations with different renal survival.

Method
We selected patients with ADPKD with measurements of height-adjusted total renal volume (HtTKV) performed with CT or MR and with GFR CKD-EPI&gt; 15 mL / min / 1.73 m2. We estimated the GFR at the end of the follow-up using the Irazábal equation and the rate of GFR deterioration, bias and precision were calculated. We analyzed the predictive power of BC using survival analysis using the Kaplan-Meier technique and using Cox regression models.

Results
We included 128 patients, aged 44 ± 13 years and a follow-up time of 79 ± 45 months (median 88), at the end of which 22 (17.2%) patients had a GFR &lt;10 mL / min / 1.73 m2 or were included in renal replacement therapy. The distribution of patients according to the CM classification was: 1A 4.7%, 1B 28.1%, 1C 33.6%, 1D 22.7%, 1E 10.9%. Age decreased progressively: 1A 58 ± 11, 1B 48 ± 14, 1C 46 ± 13, 1D 40 ± 8, 1E 30 ± 7 (p &lt;0.001). In contrast, HtTKV increased significantly: 1A 275 ± 52, 1B 486 ± 191, 1C 887 ± 410, 1D 1222 ± 510, 1E 1324 ± 800 mL / m (p &lt;0.001). While the initial GFR was not different between classes, the GFR at the end of the follow-up decreased significantly: 1A 59 ± 36, 1B 63 ± 29, 1C54 ± 35, 1D 48 ± 26, 1E 44 ± 33 mL / min / 1.73 m2 (p &lt;0.001). The GFR variation rate was significantly different according to the MCC classes: 1A 1.31 ± 6.80, 1B -2.48 ± 3.12, 1C -4.13 ± 4.33, 1D -4.70 ± 2.66, 1E -6.18 ± 3.03 mL / min / 1.73 m2 / year (p = 0.008). The final GFR predicted with the Irazábal equation was not significantly different from the real one. The absolute bias of the final GFR estimated with the MC equation was 2.6 ± 16.0 mL / min / 1.73 m2 and the relative bias was 38.7 ± 110, and it was not significantly different in the MCC classes. The P10 precision was low, with values of 65.1%, 51.7% and 50% for classes 1C, 1C and 1E respectively. The rate of deterioration of the GFR was underestimated in classes 1C, 1D and 1E. In the renal survival analysis with the Cox regression analysis, we found that the MCC classification is a predictor of survival, with classes 1D and 1E having the worst prognosis.

Conclusion
The MCC classification is capable of identifying populations that will suffer a more rapid deterioration of the GFR and constitutes a marker of renal survival in a Spanish population of patients with ADPKD. The prediction of future GFR with the Irazábal equation is acceptable as a group, although it shows a loss of precision at the individual level, especially in patients with higher GFR at baseline.