Progress report on the Nordic diltiazem study (NORDIL): an outcome study in hypertensive patients

NORDIL--the Nordic Diltiazem Study (NORDIL)--is a prospective, randomized, open blinded-endpoint (PROBE), multicenter, parallel-group morbidity/mortality outcome study in hypertensive patients designed to compare an intervention strategy based on the calcium antagonist diltiazem with a strategy based on conventional antihypertensive drug treatment (diuretics or beta-adrenergic blockers). Patient recruitment was started in Norway and Sweden in September 1992, and ended on December 15, 1996, when 10.896 male and female patients, aged 50-74 years, with essential hypertension had been randomized. In this paper we describe the baseline data of the patient cohort and blood pressures achieved in the two treatment groups during the early part of the study. The patient cohort consists of 5294 males and 5602 females with a mean age of 59.6 and 60.3 years, respectively. Concomitant disorders and risk factors in the cohort are: smoking 22%, ischemic heart disease 3.0%, previous myocardial infarction (MI) 2.0%, previous stroke 1.5%, diabetes mellitus 7.0%, and renal impairment 0.3%. There were no differences between the treatment groups in these respects. The blood pressure treatment goal is a target diastolic blood pressure of < or =90 mmHg or a 10% diastolic blood pressure reduction from the inclusion pressure. In the treatment group randomized to a diltiazem-based treatment strategy, blood pressure was 174/106 mmHg at baseline and 156/90 mmHg after 12 months of follow-up on active treatment. In the group randomized to a conventional treatment strategy, baseline blood pressure at randomization was 173/106 mmHg and 153/90 mmHg after 12 months on active therapy. The NORDIL study will terminate on October 31, 1999 and the final results should be available by mid-2000.