Modelos de predição em anomalias congênitas dos rins e do trato urinário: necessidade de cirurgia e progressão para doença renal crônica

Abstract

INTRODUTION: Congenital anomalies of the kidneys and the urinary tract (CAKUT) comprise a heterogeneous group of diseases that vary between changes in the kidneys, ureters, urethra and / or bladder. Early diagnosis is important because of its progressive nature and its potential for irreversibility. OBJECTIVES: The objectives of this thesis consist of a analysis of the surgical approach of patients with CAKUT (study 1) and a more specific one that consists of evaluating the evolution of moderate or severe chronic renal disease (CKD) in patients with posterior urethral valve (VUP) (study 2). In the first study, a prediction model was developed for the need for surgery in patients with CAKUT and, in the second study, a prediction model for evolution to moderate CKD in patients with VUP. STUDY1 - PATIENTS AND METHODS: This is a cohort study of 694 children with CAKUT admitted at the pediatric nephrology unit of our institution. Children were included between 1987 and 2013. The median age at admission was 2 months and 65% were male. Considered patient characteristics at baseline were: gender, age, serum creatinine, estimated glomerular filtration rate (eGFR), oligohydramnios, presence of other urinary tract anomalies associated with renal pelvic dilatation (RPD) (megaureter, megacystis), anteroposterior renal pelvic dilatation (APRPD) laterality (unilateral vs bilateral), presence of renal lesions (RL) on Tc99m DMSA scan, APRPD magnitude and period of admission (before vs after 2000). A prognostic model was developed using Cox proportional hazard regression analysis and backward selection. Internal validity was studied in 100 bootstrap samples. RESULTS: A total of 164 (23%) patients were submitted to surgery at a median age of 7.8 months. The predictors included in the model were eGFR, presence of other urinary tract anomalies associated with RPD, presence of RL on Tc-99m DMSA scan, APRPD magnitude and period of admission. The optimism corrected c statistic was 0.84. CONCLUSIONS: Our prognostic model for the need of surgery may contribute to identify CAKUT patients at high risk for surgical intervention. Further studies are necessary to validate the model in independent samples of CAKUT patients. STUDY 2 - PATIENTS AND METHODS: In this retrospective cohort study, 173 patients with PUV were systematically followed up at a tertiary Pediatric Nephrology Unit. The primary end-points of the study were CKD stage 3 or higher and ESRD. Survival analyses were performed respectively by Cox regression proportional hazard model with time-dependent covariables. RESULTS: After a mean time of 83 months, 65 children (37.6%) developed CKD stage 3 and 39 (22.5%) reached CKD stage 5. Fourteen (8.1%) died during follow-up. Thirty-six patients (20.8%) presented hypertension and 78 (45%) exhibited proteinuria during follow-up. After adjustment by the time-dependent Cox model, baseline creatinine, nadir creatinine, hypertension, and proteinuria remained as independent predictors of CKD stage 3 and ESRD. CONCLUSION: Our findings suggest that an earlier identification of risk factors amenable to clinical intervention might contribute to slow the progression of renal impairment.