Association of treatment groups with contrast nephropathy adjusted for multiple risk factors. *Adjusted for total volume of hydration, β-blocker, diuretic, nonsteroidal antiinflammatory drugs, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and aspirin therapies, age, gender, prior creatinine, contrast iodine load, prior exposure to contrast material, type of imaging study, heart failure, hypertension, renal failure, multiple myeloma, and diabetes mellitus.