The questions addressed by a review may be broad or narrow in scope, each review was assigned into one of the following two categories: 1) narrowly focused reviews, intervention in each review was single herb or herbal preparation, as an example of ''Chinese herbal medicine suxiao jiuxin wan for angina pectoris''; 2) broadly focused reviews, including reviews concerned multiple Chinese herbs or a family of herbal medicines sharing similar efficacy, such as ''Chinese herbal medicine for premenstrual syndrome'' and ''Chinese herbal medicine Huangqi type formulations for nephrotic syndrome''. For broadly focused reviews, we listed the number of herbs included and assessed whether the results of different herbal medicines were pooled.