Fig 4. Use of different staging systems.

A comparison is shown between the use of the five named staging systems and unnamed or unclear staging systems, between (a) study year, and (b) S. mansoni and S. japonicum. Only studies that stated study year or concerned the relevant species were included in (a) and (b) respectively. The numbers shown above each bar are the numbers of studies that used each protocol. In (a), there is a study that reported a study year before 2000, and also cited the China CDC guidance which was released after 2000. This study is a cross-sectional study design with multiple time-points, and the study year recorded is the year of the first time-point. The China CDC guidance is cited since it is used at a later time-point, after the release of the guideline.