Strengths and weaknesses
The topic of pain control in gynaecological procedures is a difficult topic to study and a significant strength of this study lies in the parallel qualitative investigation of patient attitudes and experiences. The experimental arm of this study achieved a 100% follow-up rate from baseline and was strengthened through the use of standard methods of control, including randomisation, stratification and minimisation techniques ensured comparability at baseline and minimising selection bias. Numeric Rating Scale is known to be a validated measure of pain, is easy to use, has high compliance rates and detects meaningful changes in pain and anxiety25.
One limitation of the intervention was that the video was made from a standing rather than prone perspective; the field of vision during hysteroscopy was such that the entire content of the virtual environment could not be explored and this might be addressed by development in the VR technology. Restriction of movement of the patient whilst engaging with the video in light of the nature of the diagnostic procedure could also limit the degree of immersion. The duration of the video was shorter than the length of the procedure for two patients, requiring the video to be restarted. This disrupted the immersion experience and required the health care assistant to keep a watch on when the video finished. Despite these limitations, the intervention was found to be effective in analysis.
The intervention, due to its nature, could not be blinded from the participants, so demand characteristics related to self-reporting of outcome scores may have influenced the results. Non-blinding of the participants could have resulted in patients receiving the VR intervention underreporting the pain and anxiety scores and those patients not receiving the intervention to have over-reported the scores. Additionally, the pain and anxiety scores were measured within 10 minutes of the intervention and were therefore subject to a degree of recall bias. As prior estimates of standard deviation were not available, powering the study for any expected effect size was not possible. However, we detected a relatively large significant difference between groups and therefore avoided the risk of a type 2 error. Our findings will inform sample size calculations for a future full-scale trial.
To our knowledge, this is the first randomised evaluation of feasibility, effectiveness and acceptability of a virtual reality intervention in gynaecology. However, a trial protocol has been published for a randomised controlled trial for VR analgesia for women during hysterosalpingograms and results will be forthcoming.34