be interpreted together with fig1 as efficacy of the treatments fig1 additionally reveals distinct advantages of the combination product compared with the individual products table 4 shows estimates of the median down time the time at which the survival rate in the population of experimental animals just reaches 50 according to this the proportion of surviving animals in the placebo group has fallen to 50 after only 1 5 months whereas this is not to be expected until after 8 months with a combination treatment the individual products achieve a median survival time of 4 months which is less than half that of the combination product the statistical analysis was carried out essentially using the sas stat procedure lifetest sas institute inc 1989 sas stat user 39 s guide version 6 4th edition volume 2 cary n c sas institute inc the log rank tests were carried out pairwise on the experimental groups and adjusted to obtain a multiple significance level of 5 according to holm s holm 1979 a simple sequentally rejective multiple test procedure scand j statist 6 pp 65 70 the individual products ramipril and cariporide lead to a statistically significant improvement in the survival rate compared with the placebo treatment no significant differences in the survival rates between cariporide and ramipril were detectable at the chosen significance level the combination treatment is significantly superior to the two individual products chronic hypertension leads in the old spontaneously hypertensive animals to transformation processes in myocardial tissue which essentially correspond to those taking place in humans in an early phase months 10 15 of life compensated heart failure with hypertrophy nyha stage i ii and in the later phase months.