Most common predisposing factor for chronic pyelonephritis is:
Diabetes mellitus
Renal stone
Posterior urethral valve
Vesicoureteric reflux
Chronic pyelonephritis is so often associated with vesicoureteric reflux that some feel that it is better named "Reflux nephropathy". It is impoant cause of renal damage and death from end - stage renal failure.
Kidney and ureter