Table 1

Distinguishing competing evidence equipoise from insufficient evidence equipoise

 Clinical evidence base carries sufficient probative force to reasonably conclude that antibiotic prophylaxis is NOT effective in reducing IE Clinical evidence base carries insufficient probative force to reasonably conclude that antibiotic prophylaxis is NOT effective in reducing IE Clinical evidence base carries sufficient probative force to reasonably conclude that antibiotic prophylaxis is effective in reducing IE Competing evidence equipoise Conclude antibiotic prophylaxis is effective in reducing IE Clinical evidence base carries insufficient probative force to reasonably conclude that antibiotic prophylaxis is effective in reducing IE Conclude antibiotic prophylaxis is NOT effective in reducing IE Insufficient evidence equipoise
• Here sufficient evidence of efficacy can be regarded to be at the level generally accepted in clinical medicine, ie, where there is sufficient evidence to be able to conclude that the null hypothesis can only be true with a low (essentially arbitrary but generally accepted) probability of less than 1 in 20 (ie, p<0·05) thereby permitting rejection of the null hypothesis.22

• IE, infective endocarditis.