Results
There was a very close consensus between the paired reviewer scores with identical RS occurring for six of the eight studies (kappa statistic: P=0.97). Only 3 items among a total of 40 differed. The average scores obtained for each of the five items of the RS, as well as the summary RS for the eight studies reviewed, are displayed in Table 2. The RS maximum possible total score was 14. The articles that showed a PB dose–volume relationship consistently scored much higher on average than the other four articles that did not find this relationship (Figure 1). These 'positive' articles were Fisch et al., Roach et al., Wernicke et al. and Mangar et al. They all scored very highly on the potency proportion before EBRT, dose ranges, threshold and PB definition items. On the other hand, the four 'negative' articles received higher potency evaluation scores reflecting the method for assessment.
(Enlarge Image)
Figure 1.
Average results of both reviewers, expressed in terms of the 'reliability score' (maximum possible score=14 points). (a) Average total results of each study. (b) Average total results grouped by 'positive' and 'negative' studies.
The Roach et al., Wernicke et al., Mangar et al. and van der Wielen et al. papers scored highest in the potency before EBRT category, with 100% of patients included demonstrating potency before treatment.
Brown et al. and Weigner and King used the most rigorous potency evaluation instruments, the IIEF and the EPIC.
Dose ranges to the PTV, with multiple observers, were consistently higher in the four articles that found a dose–volume relationship between ED and the PB dose. However, it was also higher in the van der Wielen et al. study.
A threshold dose to the PB was found to cause impotence in the four studies that conclude a dose–volume relationship.
As for the PB definition, Wernicke et al. and the Selek et al. studies defined how it was contoured, however, they did not specify how many researchers outlined it. The Brown et al. and Wiegner and King papers did not explain how the contouring had been done. Lastly, van der Wielen et al. only contoured the PB until both corpora cavernosa did not join together, which is inconsistent with the other studies.