G-006 CARDIOVASCULAR OUTCOMES IN HYPERTENSIVES TREATED EXCLUSIVELY WITH NIFEDIPINE GITS OR CO-AMILOZIDE

Abstract

Background The International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment (INSIGHT) study was designed to investigate whether prevention in hypertensives at high cardiovascular risk cardiovascular disease was similar or different by treatments based on the long-acting calcium-channel blocker nifedipine GITS) or on the fixed dose combination of the diuretics hydrochlorthiazide and amiloride (co-amilozide). As INSIGHT included a relatively large number of patients whose blood pressure (BP) was controlled without the need for further add-on therapy, there was an opportunity to compare cardiovascular (CV) outcomes in this sub-group of patients who remained on “mono-therapy” throughout the trial. Methods Treatment groups were compared by the log-rank test without adjustment for covariates. Relative risk (RR) with 95% CI's were obtained using Cox proportional hazards models with treatment allocation as the only covariate. The significance of the association between the two treatment groups was evaluated using Fisher's Exact test. Results Throughout the trial.3726 of the 6321 (59%) randomised patients remained on their initially prescribed therapy without the requirement for additional antihypertensive therapy. At baseline the two treatment groups were well balanced with respect to demography and additional risk factors. After 3 years of follow-up the achieved BP was comparable in both groups (nifedipine GITS 136.7/80.4 mmHg; co-amilozide 135.9/81.0 mmHg). For the primary composite endpoint there were 111 (5.8%) events in the nifedipine group and 90 (5.0%) in the co-amilozide group with a relative risk of 1.17 (95% CI 0.88, 1.56: p = 0.277). For the secondary composite endpoint there were 218 (11.4%) events in the nifedipine group and 198 (10.9%) in the co-amilozide group - relative risk of 1.04 (95% CI 0.85, 1.28: p = 0.716). None of the individual components of the primary and secondary endpoints showed statistical significant differences between the treatment groups although there was a trend for angina (worsening or new) to be reduced by nifedipine GITS – (RR = 0.60: CI 0.36, 0.99): p = 0.058). Conclusions Whilst retrospective analyses cannot be considered to be definitive, theses results indicate that the CV outcomes in high risk hypertensives are comparable in patients who were exclusively treated with nifedipine GITS or co-amilozide. Given the central role of diuretics in hypertension treatment guidelines, these findings indicate that antihypertensive therapy with nifedipine GITS is equivalent to a regimen based upon a fixed combination of diuretics.