Blood Pressure and Urine Protein Levels with the Least Risk for Worsening Kidney Disease. Ann Intern Med. 2003;139:I-36. doi: 10.7326/0003-4819-139-4-200308190-00002
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Published: Ann Intern Med. 2003;139(4):I-36.
Chronic kidney disease can cause a gradual and progressive loss of function in both kidneys. Most patients with chronic kidney disease have high blood pressure (hypertension) and high levels of protein in their urine (proteinuria). Doctors use drugs called antihypertensive agents to reduce both blood pressure and protein in urine. Some of these drugs, such as angiotensin-converting enzyme (ACE) inhibitors, clearly prevent worsening kidney function.
Guidelines recommend that doctors reduce blood pressure to less than 130/80 mm Hg in patients with kidney disease. Some recommend reducing blood pressure to even lower levels (<125/75 mm Hg) in patients who lose more than 1 gram of protein in their urine per day. A few studies, however, suggest that reducing blood pressure too much may be harmful and increase the risk for heart attacks. Whether very low blood pressure could worsen kidney function is also questioned.
To determine the levels of blood pressure and protein in urine that are associated with the lowest risk for worsening kidney disease.
1860 patients with high blood pressure or decreased kidney function. None had diabetes.
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.
Higher systolic (the top number), but not diastolic (the bottom number), blood pressure was strongly related to risk for worsening kidney function. Risks for higher systolic pressure were marked in patients with urine protein levels greater than 1.0 gram daily and were not apparent in patients with urine protein levels less than 1.0 gram daily. Patients with systolic pressures of 110 to 129 mm Hg and urine protein levels of less than 1.0 gram daily had the lowest risk for worsening kidney disease. Very low systolic pressure (<110 mm Hg) was associated with increased risk for worsening kidney disease.
Because few patients had heart problems, the researchers couldn't assess blood pressure levels associated with the lowest risk for heart disease. The study examined associations observed in trials that were designed to compare effects of different antihypertensive regimens. Randomized trials that are actually designed to compare different blood pressure and urine protein targets are needed to confirm the findings.
Systolic blood pressure of 110 to 129 mm Hg is associated with the least risk for progression of kidney disease in patients with urine protein levels greater than 1.0 gram daily.
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