To investigate the outcomes of comparative studies on photoselective vaporization of the prostate (PVP) as a function of risk of bias (RoB), conflicts of interest (COI), and industrial sponsorship (IS).
We performed a systematic literature search for comparative studies on PVP [randomized controlled trials (RCTs) and non-randomized comparative studies (NRCSs)]. Study selection as well as comprehensive assessment of RoB, COIs, and IS were performed in duplicate. The identified studies were further rated by two independent board-certified urologists as either PVP-favourable or PVP-unfavourable. Descriptive statistics were performed among all identified studies and among the subgroups of studies rated as favourable and unfavourable, respectively.
Sixty-five studies qualified for inclusion (25 RTCs and 40 NRCSs) of which 56 (86%) were rated favourable and 9 (14%) unfavourable. A majority of all studies mentioned the absence/presence of potential COIs (78%). In contrast, a sponsorship statement was only found in 29% of the investigations. Studies rated favourable demonstrated a higher percentage of COIs (39% versus 22%). IS was exclusively found among favourable studies. Furthermore, a serious or critical RoB was more often found in favourably rated NRCSs.
COIs and IS seem to be associated with favourable study outcomes in comparative studies on PVP. The transparency of the whole research process from study conception to the dissemination of the results has to be further improved to prevent a harmful effect of COIs and IS on the internal validity of studies.