Hypertensive nephrosclerosis: wider kidney biopsy indications may be needed to improve diagnostics.

BACKGROUND Hypertensive nephrosclerosis is the presumed underlying cause in many end stage kidney disease (ESKD) patients, but the diagnosis is disputed and based on clinical criteria with low diagnostic accuracy. OBJECTIVE To evaluate and improve the diagnostic process for nephrosclerosis patients. METHODS We included adults from the population-based HUNT study (n=50,552), Norwegian CKD patients referred for kidney biopsy 1988-2012 (n=7,261), and unselected nephrology clinic patients (n=193) used for matching. Decision tree analysis and ROC curve-based methods of optimal cut-offs were used to improve clinical nephrosclerosis criteria. RESULTS Nephrosclerosis prevalence was 2.7% in the general population, and eGFR decline and risk for kidney-related hospital admissions and ESKD were comparable to patients with diabetic kidney disease. In the biopsy cohort, current clinical criteria had very low sensitivity (0.13) but high specificity (0.94) for biopsy-verified arterionephrosclerosis. A new optimized diagnostic algorithm based on proteinuria ( 155mmHg), and age (>75years) only marginally improved diagnostic accuracy (sensitivity 0.19, specificity 0.96). Likewise, there was still false positive cases with treatable diagnoses like glomerulonephritis, interstitial nephritis, and others (40% of all test-positive). Decision curve analysis showed that the new criteria can lead to higher clinical utility, especially for patients considering the potential harms to be close to the potential benefits, while the more risk tolerant ones (harm:benefit ratio <1:4) should consider kidney biopsy. CONCLUSION Further improvements of the current clinical criteria seem difficult, so risks and benefits of kidney biopsy could be more actively discussed with selected patients to reduce misclassification and direct treatment.