Table 2. Correlation between estimated burden of disease and number of randomised controlled trials and enrolled subjects All major categories of disease Infectious disease category r* P value r* P value Burden of disease in 2000 and:   Total No of trials 0.53 0.024 0.85 <0.001   No of trials with n>100 0.64 0.004 0.79 0.001   No of trials with n>500 0.61 0.007 0.78 0.001   Total No of randomised subjects 0.68 0.002 0.25 0.39 Burden of disease in 1990 and:   No of trials before 1990 0.35 0.15 0.67 0.009   No of trials before 1990 with n>100 0.61 0.009 0.62 0.018 * Spearman's correlation coefficient.