A mixed-methods pilot case-series approach was used. The quantitative a priori hypotheses tested were that for patients with established chronic pain treated at home: (1) exposure to VR for 30 min 3 times a week would decrease pain scores from their preexposure baseline, and (2) exposure to VR sessions 3 times a week would lead to decreased weekly pain scores over a month. The qualitative aspects of the study examined patient’s perceptions of their pain while using VR, if they observed any practical application of safety issues in using VR or experienced any adverse effects. Also, their VR experience preferences, and if they noted any functional or quality-of-life improvements during the study were examined.

Prior to recruitment, a review of the proposal was undertaken by the UBC Clinical Research Ethics Board and approval granted. A purposeful nonprobability convenience sample of 10 adult patients with a diagnosed chronic pain condition for at least six months were recruited by Web-based invitations from 2 sources; PainBC and the People in Pain Network. Both are charitable support organizations, based in British Columbia. Interested patients were sent further information and a telephone interview by a member of the research team was conducted to answer the patients’ questions and screen them against specific inclusion and exclusion criteria (see Textboxes 1 and 2). Suitable patients were then sent an informed consent form to be signed and returned on installation of the VR equipment (with a duplicate copy provided for them to retain).

A home-based VR intervention was selected for the study. First, for practicality, as many of these patients also had mobility concerns and it was not economical to offer transportation to a hospital or lab and back again several times a week. Second, commercial VR systems would need to be suitable and easy to use at home, if they proved efficacious in the treatment of chronic pain. The VR hardware used was identical for each patient, and consisted of a high-end personal computer running the VR applications with an Oculus Rift DK2 110⁰ field of view (FOV) stereoscopic head-mounted display (HMD) with a resolution of 960 × 1080 pixels per eye.

As there were no VR experiences validated in the context of chronic pain, one of the project’s aims was to explore whether patients expressed preferences for different VR environments. Four categories of VR experience were devised, and VR applications were purposefully selected and tested in advance for potential efficacy by the researchers for use in each of the 4 weeks of the study. In week 1, the participants undertook passive VR experiences where they simply travelled through a VR environment. These included a virtual Iceland, and a boat ride through an artistic experience (Senza Peso). In the second week, mindfulness and meditative introversion focused VR applications were used, as these have been associated with pain control in other studies [29,30]. These experiences involved flying through 3D mandalas, or experiences that altered the user’s environment depending where they looked (Sightline). In the third week, active exploratory VR environments were used, where the participant could explore a new environment at will (an underwater environment, the solar system, and a natural environment). In the final week, active problem-solving experiences were used (eg, game type environments requiring participants to solve 3D puzzles). These different applications allowed for comparison of the VR environments in terms of any reported specific effects on patient’s pain experiences and side effects, and also prevented boredom with the VR experiences available at the time. An identical protocol of specific VR experiences to be used for 30 min on every other day of the study was given to each patient (see Figure 1). A simple computer menu system was devised so that patients could easily start each VR application on the appropriate day in sequence (as per protocol). Daily VR activity was logged, with arrest from VR at weekends.

Three sets of equipment were used concurrently with different patients, and then moved on to the next patients who had volunteered on a previously arranged schedule. The equipment was installed in the patients’ home with a 90-min training session on how to use the VR and perform data collection procedures. Patients were also assessed as being able to navigate the VR experiences and use the equipment comfortably at the end of this. During the study time patients also had access to a member of the research team by telephone and email for trouble shooting and to discuss any issues associated with the study.

Given an absence of prior work with VR and chronic pain, an initial exposure to 12 therapeutic sessions of 30 min was identified as reasonable to explore the clinical effects of VR initially. VR research in acute pain settings was usually of 15-30 min duration [2] and in associated pain hypnotherapy studies that used 4-6 sessions had less success whereas studies that had offered 8-12 sessions with lengths of treatment exposure between 30 and 40 min established positive results [31,32].

To ensure the multidimensional aspects of chronic pain experienced by individuals were adequately measured, various tools were selected that addressed different aspects of chronic pain. These were self-recorded by patients in a supplied binder.

Quantitative data were explored for any differences in the average pain scores for the VR intervention at each time point to analyze for any indications of changes in pain immediately following the VR experience, and at 6 and 24 h after exposure, and for cybersickness. Descriptive univariate statistics were analyzed to support a preliminary understanding of the impact of VR on an individual’s pain experience and nature of the data obtained. A simple initial pre-post exposure NRS analysis was then undertaken using a Wilcoxon matched pairs test. For the BPI and S-LANSS scores, a Freidman test (the nonparametric alternative to the one-way repeated measure ANOVA) was undertaken to explore for any trends evident over the whole month using SPSS 23 statistical software (IBM).

Qualitative data were transcribed from the original sources into Nvivo 7.0 qualitative analysis software. It was analyzed using an interpretive-description (ID) approach for an open exploration of participant’s experiences to further understand the perceptions associated with the use of VR and any impact on their chronic pain. ID assumes preexisting theoretical knowledge, and that clinical patterns exist, and rather than trying to avoid preconceptions in the analysis, coding proceeds on the basis that no matter how participatory and collaborative the analytical method is, it will finally be the researcher who determines what data are significant [42,43]. An ID approach allowed for an inductive descriptive analysis of the phenomena, using iterative readings of the combined qualitative data and coding by 2 independent members of the research team. Analyses were then merged to establish key thematic elements, patterns, and theory associated with the patient’s experiences [42].

As is common with chronic pain studies, the study encountered attrition and 8 patients (n=8, 33% attrition) completed the full study protocol, and only 6 of these consented to post experience interviews [44,45]. Reasons for discontinuation were not required, although one indicated it was due to cybersickness. The patients’ pain conditions and histories are summarized in Table 1.

A descriptive statistical exploration of the various pain scores confirmed the data were not normally distributed. Univariate comparison of the mean NRS pre-post test scores demonstrated a slight decrease in pain for most interventions (see Figure 2), although for one intervention (#10) a slight increase in pain was also observed. This likely reflected user frustration with the Subnautica prerelease app, which had not yet implemented game-controller functionality, so participants had to move around using keyboard controls, which was difficult with an HMD on. No reduction in NRS scores 6 and 24 h later was evident. Furthermore, a Wilcoxon Matched Pairs Signed Ranks test for means for each VR intervention demonstrated no significant effect between pre- and postexposure for NRS scores (see Table 2). Given the lack of any significant pre-post exposure effects, no further exploration of NRS scores was performed. The Friedman test run on the BPI and SLANNS scores as repeated measures for each participant at the end of each week also indicated no statistically significant difference in the pain reported over the 4 weeks. BPI Worst Pain: x²=1.6, P=.82 BPI Average Pain: x²=5.2, P=.27; BPI Least Pain: x²=4.6, P=.20. BPI Pain Now: x²=2.9, P=.57. S-LANSS x²= 1.0, P=.91. As no significant findings were obtained, no further post hoc analysis was performed.

Four major thematic areas emerged from the interview analysis: design of the VR experiences, efficacy of VR for chronic pain, limits of the VR technology, and practicality of use as an adjunctive therapy (see Table 3). The subthemes evident in these are described below together with participant quotes.

There was a distinct difference in participants’ perceptions of the value of VR environments designed to be interactive versus those designed to promote relaxation. Half of the interviewees believed that the interactive experiences were more beneficial. For example:

Two participants reported they actively disliked the relaxation-based VR experiences:

However, 3 participants favored the relaxing experiences as in:

There appeared no relationship between the type of VR experience people preferred and types of pain they experienced.

The second theme related to the efficacy of the VR experiences in helping reduce pain. Four of those interviewed identified positive benefits during the VR experience:

Participants who experienced positive effects, distraction was frequently highlighted as the rationale:

All the participants who found benefits, all reported the experience was transient and did not persist long after the VR experience:

Two participants reported the VR experiences were not effective for helping reduce their pain:

One participant (#10) who had reported positive effects with some of the VR experiences noted one actually caused her stress, increasing her pain:

Although conversely, another acknowledged:

The technological functionality (and limits) of the available VR experiences also emerged as noteworthy. Four participants identified that they became quite frustrated with the VR systems in use, because of complex or cumbersome control systems:

The comfort of the HMD drew both positive and negative comments. One user believed that the HMD was “…nice and comfortable it was relatively small.” (Participant #1), whereas 2 others complained about issues trying to use the HMD with eyeglasses:

Similarly, another theme on the practicality of using VR was evident. The side effect of cybersickness was significant and reported by 5 of the 8 participants (60%) for a least one VR experience in the self-reporting forms, and it also arose as a topic of interest in the interviews:

Most of the responses noted mild nausea being induced when experiences involved rapid speed or motion, or moving in 3 dimensions (such as in the spacecraft simulator), which was resolved when they slowed the experience down or had a break. However, 1 participant noted the symptoms persisted for some time after the VR experience:

Two participants also noted minor claustrophobia as a side effect:

The issue of being able to engage with a VR experience when the participant was experiencing severe pain also arose as a practical limitation. In 2 cases, they reported they were in too much pain to use the VR equipment.

Although there were no significant pre-post exposure changes in the reported pain scores, more than half (5 of 8) of the participants did report positive benefits on their perceived pain from the use of VR. However, 3 of the participants interviewed reported none. The effects of VR on chronic pain would appear to be very individualized. No evidence that any benefits of using the VR on the participant’s pain persisted postexposure was found. For participants who identified positive results, distraction was described as the mode of action by them. This is consistent with other researchers who suggest the deeper form of distraction produced with VR experiences is the main mechanism by which pain is attenuated [19,20,22,31,46].

Chronic pain patients respond in very individualistic ways to VR as indicated by the varying preferences for interactive versus relaxing forms of VR reported. Some had very negative reactions to the relaxation introversion-focused experiences, whereas others enjoyed them. This finding is consistent with work that reports some individuals are actually relaxation-sensitive and paradoxically find relaxing experiences increase their stress levels [47,48]. Although no significant improvement in BPI and functionality was evident over time, one of the participants did report improved mobility following the VR experiences. Functional improvement has also been reported in other VR studies [49-51].

It was evident that VR technology remains immature in the technology life cycle, the progression from research and development, commercial production, to succession by superior technologies [52,53]. Most participants reported some technical issues with either the hardware or software during the experience. However, the possibility of achieving nonpharmacological pain relief may encourage more chronic pain suffering to experiment with VR, as they are more likely to experiment when pharmacological and other medical therapies fail [54,55].

The most significant adverse reaction to VR was cybersickness, as 60% of the participants experienced this at some time during the study. This side effect of VR is well documented, but should not be underestimated as a factor that may influence uptake [28,39-41,56-59]. Other than cybersickness, no significant adverse effects were noted.

As an initial exploratory study, this work has limitations. Case series are vulnerable to selection bias and may not represent the wider population, and with small-scale studies such as this, the effects seen may be due to intervening effects such as the placebo, Hawthorne, or Rosenthal effect. Therefore, internal validity and reliability may be limited. Technological immaturity of the experimental setting is also a limitation. Strengths of the study include the inductive ID approach, which is more responsive to clinical experience-based questions here. Furthermore, an exploratory pilot study provides an appropriate approach at this fundamental stage of clinical research to inform future work.

Work in this area is in its infancy and clinical studies limited. The complexities of chronic pain make finding pain-management solutions challenging, and the results reflect those complexities. The following conclusions were drawn from the results:

Exposure to VR for 30 min a day every other day for chronic pain patients in self-administered therapy sessions resulted in:

The majority of this study participants reported a reduction in pain while they were using the VR, but with highly individualized responses. Findings, as with other recent work suggests that VR maybe a useful short-term adjunct for the management of chronic pain, but individual choice in the form of VR experience may be as significant as the VR medium itself [60]. Although statistically significant reductions in pain scores postexposure were not demonstrated, in the qualitative analysis, participants reported mostly positive impacts on their pain experience, and one reported that the VR experience did appear to improve their mobility. Whereas longer-term benefits of VR therapy as an adjunctive for chronic pain were not demonstrated, the immediate relief experienced by patients here during VR would indicate the therapy has potential for a means of providing respite from the constant pain they experience.

Attention to practical implementation is important, particularly having good orientation practices and technical support available to patients at home. Robust controlled trials with larger samples, comparing VR with other forms of multimedia and neurological studies are now required to establish efficacy. Practical methods to research VR interventions should include both active and passive interventions, and larger cohort studies including assessment of cybersickness (and factors that ameliorate its effects) as the most significant adverse effect.

In conclusion, home-based VR therapy is a feasible option for chronic pain sufferers. There remains a pressing need for non-opioid alternatives in the treatment of chronic pain, and in light of the patient’s experiences documented here, individual tailored VR solutions would appear more likely to be successful compared with a unidimensional off-the-shelf VR experience.