Rather than doing a new study, the researchers analyzed information from 11 randomized trials that had compared effects of antihypertensive regimens with or without ACE inhibitors. Patients in the trials had high blood pressure, decreased kidney function, or both. They were followed for at least 1 year to assess worsening kidney disease. During follow-up, blood pressure and urine protein levels were monitored regularly. Worsening kidney disease was defined as either kidney failure or a doubling of serum creatinine levels, which are measured by a blood test that shows kidney damage. The researchers combined the results from all of the trials to see which levels of blood pressure and protein in the urine during follow-up were associated with the least risk for worsening kidney disease.