Prognosis

The risk of worsening renal function is increased with ^a

• a resistance index of 80 or more ( = [1 - (end-diastolic velocity/maximal systolic velocity)] x 100)
• creatinine clearance < 40 ml/min

and reduced with smoking.

Why?

A high resistance index makes worsening renal function much more likely

Patient	Prognostic Factor	Outcome	CER	OR (95% CI)	NNF+ (95% CI)
renal artery stenosis a	resistance index 80 or more independent	worsening renal function at 32 months	3.1%	1390 (50 to 38400)	1 (1 to 2)
	creatinine clearance < 40 ml/min independent	worsening renal function at 32 months	24%	12.7 (1.7 to 95)	2 (1 to 9)
	smoking independent	worsening renal function at 32 months	24%	0.04 (0.0 to 0.5)	-4 (-10 to -4)