The "Relative risk" of 0.25 indicates-
Defined as the ratio between the incidence among exposed persons and incidence among non exposed. A typical case-control study does not provide incidence rates from which relative risks can be calculated directly because there is no appropriate denominator or population at risk to calculate these risks Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 86
75% reduction of the incidence rate in the exposed individuals compared with the unexposed
25% increase in the incidence rate in the exposed individuals compared with the unexposed
2.5 % times higher risk in the exposed individuals compared with the unexposed
75% risk increase in the exposed individuals compared with the unexposed
Epidemiology