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International Nifedipine GITS study: Intervention as a Goal in Hypertension Treatment - INSIGHT
Description:
The INSIGHT trial compared the effects of the calcium-channel blocker nifedipine once daily with the diuretic combination co-amilozide on cardiovascular mortality and morbidity in highrisk patients with hypertension.
Hypothesis:
The primary hypothesis was there would be a 25% relative difference in the primary outcome between nifedipine and co-amilozide. The secondary hypothesis was that there would be non-inferiority in the primary outcome between nifedipine and co-amilozide, defined as a non-significant absolute difference.
Study Design
Study Design:
Patients Enrolled: 6321
Mean Follow Up: 3 years
Mean Patient Age: 55-80 years
Female: 54
Patient Populations:
Systolic blood pressure >=150 mm Hg and diastolic blood pressure >=95 mm Hg, or systolic blood pressure >=160 mm Hg. One of the following cardiovascular risk factors: hypercholesterolemia; smoker; family history of myocardial infarction in parent or sibling before age 50 years; current left-ventricular hypertrophy, confirmed by echocardiography; coronary heart disease, defined as stable angina or symptomless coronary heart disease; left-ventricular strain; peripheral vascular disease, defined as intermittent claudication, resting pain, or gangrene; proteinuria. Age 55-80.
Exclusions:
Documented secondary or malignant hypertension. History of sub-arachnoid hemorrhage. PTCA or CABG in the 6 months prior to entering the study. Myocardial infarction or stroke in the 12 months prior to entering the study, or patients whose ejection fraction post-MI is <40%. Congestive heart failure with a known ejection fraction <40%. Known hypersensitivity to dihydropyridines.
Primary Endpoints:
Composite of death from any cardiovascular or cerebrovascular cause, non-fatal stroke, myocardial infarction, and heart failure
Secondary Endpoints:
Total mortality Death from a vascular cause Non-fatal vascular events including transient ischemic attacks, angina (new or worsening), and renal failure
Drug/Procedures Used:
Nifedipine, 30 mg daily; or co-amilozide (hydrochlorothiazide 25 mg, amiloride 2.5 mg daily). All patients received one active and one placebo tablet taken at the same time of day.
Principal Findings:
The primary outcome (Composite of death from any cardiovascular or cerebrovascular cause, non-fatal stroke, myocardial infarction, and heart failure) occurred in 6.3% of patients in the nifedipine group and in 5.8% in the co-amilozide group (RR 1.10, 95% CI 0.91-1.34, p=0.35). Mean blood pressure fell from 173/99 mm Hg to 138/82 mm Hg in both groups. There were fewer serious adverse events in the nifedipine group than in the co-amilozide group (25% vs 28%, p=0.02). Groups did not differ for all-cause mortality, non-fatal endpoints, or the combined secondary endpoints (p=NS for all).
Interpretation:
Nifedipine once daily and co-amilozide had a similar efficacy in high risk patients with hypertension, suggesting the choice of drug can be determined by tolerability and blood-pressure response rather than long-term safety or efficacy.
References:
Lancet 2000;356:366–372
Keywords: Intermittent Claudication, Myocardial Infarction, Stroke, Gangrene, Angina, Stable, Diuretics, Risk Factors, Proteinuria, Hypercholesterolemia, Nifedipine, Peripheral Vascular Diseases, Calcium Channel Blockers, Drug Combinations, Heart Failure, Hydrochlorothiazide, Hypertrophy, Hypertension, Echocardiography
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