In the following, the results for the identified dimensions from the summarizing content analysis of the interviews with the CBP patients and the focus groups with the physiotherapists and psychotherapists will be presented. The dimensions consist of semantic levels, which resulted from the clustering of the content analysis and represent the code groups that emerged. Each level consists of the requirements that were gathered from interviews with all stakeholders. After decoding of the requirements rankings (transformation of rankings into percentiles) we were able to calculate average values within the stakeholder groups for the requirements. The rating of each stakeholder’s opinion for each dimension made it possible to identify a "winning stakeholder". Each semantic level of the dimensions is presented in the following by the requirements that were prioritized as the most important.
3.1 Overall System
This dimension consists of the following levels: briefing/instruction, handling, duration of use, safety and price/financing. In the dimension overall system, the participants identified the physiotherapists as the most important stakeholder. The psychotherapists were ranked 2nd and the CBP patients 3rd. The ranking of the requirements of physiotherapists were taken over for this dimension.
The physiotherapists considered the requirement: The system should offer an individual briefing as the most important requirement in the semantic level briefing/instruction. There are several ways that the system could be made usable for geriatric chronic back pain patients. The system should offer a demo (tutorial) for correct operation was prioritized as the second most important requirement. The briefing should be carried out by personal assistance was prioritized with rank three. Both of these requirements are possible solutions for an individual briefing.
On the level of handling the most important requirement was: The system should be easy to handle. For some subjects the demo in the task-based part was already too difficult to use. “Yeah, that would really have to be under guidance, yeah. […] So they [peers] wouldn’t be able to do it alone” (CBP patient). This underlines the importance of the user-centered design, which is applied in the project through usability evaluations with the purpose of creating the most appealing and functional operation possible for the age group; if this is not possible, then use of the system under personal supervision must be considered.
The physiotherapists considered the requirement: The system should offer breaks between exercises to be the most important requirement in the level duration of use. Especially during home exercises, patients showed inconsistency in taking breaks. “No, it then automatically follows that one stops or does not stop” (CBP patient). Mostly the seniors in the groups performed the exercises all at once and without a break as a matter of course. Newcomers may be prone to overestimating themselves; especially in cases of chronic pain, over-ambitiousness can lead to severe pain. The patients should learn for their everyday life what individual dose of exercise is right for them and therefore they should have the opportunity to take a break. Another requirement the participants stated, was: The exercises should last a maximum of 30 minutes. Further a very important requirement was: The system should offer 15 minutes of relaxation. Psychoeducation plays an important role in multimodal pain therapy. The requirements analysis showed that relaxation therapy in VR can be offered in addition to movement training, but it should take less time in the game.
The physiotherapists considered the following requirement to be important in the level of safety: The system should be used in a safe place with sufficient space. Due to the lack of perception of the real space, many older adults can be exposed to the risk of falling. "Of course, you must do such things [...] in a safe environment where there’s just enough room that you can’t knock anything over or put yourself in danger" (CBP patient). This implies that a concept for safe use of the exergame is needed. The system should allow you to sit down. This approach also involves the risk of falling, which can result from overexertion, for example. A possibility of sitting or even executing the exercises in seated position would minimize the danger of falling. The following requirement was also given: The system must contain a help button.
In the level of financing the requirement: The system should be offered for rent was preferred. “Renting would be a good solution.” (CBP patient). This proposal would allow multiple users to share the system and make it available to a larger number of potential users.
3.2 Hardware
This dimension did not consist of various levels. Due to the small number of requirements and semantically similar requirements, code groups were not created in the content analysis and were not presented in the prioritization as levels for this dimension. For this reason, this dimension consists of only one level. In the dimension hardware, the participants also identified the physiotherapists as the most important stakeholder. The psychotherapists were ranked 2nd and the CBP patients 3rd.
The physiotherapists determined the most important requirement to be the following: The patients should be able to put on the googles by themselves. This requirement is associated with another important requirement: The goggles should be easy to put on and take off. The ability to put the goggles on and take them off independently was perceived as important in order to enable the system to be used independently at home by older CBP patients. Here the hardware design must be adapted to the requirements of the seniors.
3.3 Software
The software dimension consists of the following levels: in-game environment, application of game and exercises. In the dimension software, the participants identified the physiotherapists as the most important stakeholder. The psychotherapists were ranked 2nd and the CBP patients 3rd.
The decisive requirement in the level in-game environment was: The system should perform an individual calibration (e.g. to detect movement limitations). The desire for calibration was mainly expressed by the physiotherapists. With an individually adapted environment, limitations of the patients could be integrated into the game. Patients are thus not forced by the game environment to make movements that they cannot functionally perform, e.g. due to a limited range of motion in a joint. "Yes, but I could imagine, for example, that [...] the environment knows how big the patient is. Or how high he can stretch to get it calibrated" (Physiotherapist). The physiotherapists stated that they could imagine, for example, a movement assessment in the VR to be carried out by the patient before the start of the game.
In the semantic level application of game the requirement: The system should enable the therapist to intervene on patients (pain, anxiety, incorrect execution) was prioritized in first place. This requirement of course depends on the setting in which the exergame is performed. If the exergame is performed in a setting in which the therapist stands next to the patient, immediate intervention is possible. In a setting where the patient performs exercises independently at home, a concept must be considered for the therapist’s intervention (e.g. though a help button/emergency-supporting system). "Well, definitely intervene when there’s fear, when there’s irritation [...] can be a technical problem. [...] And of course even if I feel like someone can't handle it, or do something completely different than (laughing) actually the model" (Physiotherapist). The physiotherapists could consider an intervention, e.g. by assisting or stopping the game, if the patient experiences severe pain during the game, is afraid while playing, or performs the exercises incorrectly, which can lead to danger or increased back pain. During the task-based part, the phenomenon of cybersickness in a subject was detected once, but disappeared after a short break (approx. 5 min).
In the level of exercise the requirement: The patients should perform everyday exercises was preferred. The physiotherapists see the VR as a chance to try out tasks that are close to everyday life in a realistic way. "In the training program one could use environments / tasks that are attractive for many older people or are close to everyday life – such as the garden ... planting something, harvesting or maybe shopping" (physiotherapist).
3.4 Gamification / game integration
This dimension consists of the following levels: display of feedback, biofeedback, progress, and storytelling. In the dimension: gamification / game integration, the participants identified the psychotherapists as the most important stakeholder. The physiotherapists were ranked 2nd and the CBP patients 3rd.
At semantic level display of feedback the following requirement was perceived as the most important: The feedback in the system should always reinforce positively, never negatively. In the interviews, the physiotherapists also named this as an important method for giving feedback. This is particularly important in order to stabilize a long-term intrinsic motivation of CBP patients during the exercises in the exergame in order to support long-term training adherence.
In the level of biofeedback the participants considered the requirement: The exergame is intended to provide the user with behavioral recommendations (e.g. advice on how to relax) to be the most important requirement in the level of biofeedback. During the interviews the psychotherapists always expressed their views on psychoeducation in the exergame: “Well education, I think, is of course very, very important in terms of stability of the spine for example, if there are fears, like: ‘that breaks everywhere and [...]’ ” (Psychotherapists). In classical multimodal pain therapy, behavioral therapeutic aspects play an important role. These aspects should also find their place in an exergame for CBP patients. Particularly in forming habits, patients must be aware of why they perform the exercises and what can cause them harm. It is precisely through misconceptions that many patients develop fear avoidance beliefs or poor stress management. In order to avoid and counteract these negative strategies, the system can be supported by e.g. stress sensors that measure the pulse during training and to give positive feedback of vital parameters. By using quantitative measurable methods, behavioral recommendations can be made usable, comprehensible for the user, which contribute to therapy adherence (Figure 3).
On the level of progress the most important requirement was: The system should display praise and rewards (for example, text "Hooray", "Congratulations"). The seniors often stated during the interviews that rewards after completing a task in the game would please them. “Well, all right. A reward if you do the task or something. Like I said, I'm not the person who wants to win while playing. The thing itself has to be fun and it has to have something to do with creativity” (CBP patient). Figure 3 shows how progress is structured in the game and how it can lead to long-term motivation for the exercises, which is necessary in the case of chronic back pain. Since training progress is required with chronic patients, because of the poor exercise adherence and the risk doing exercise wrongly, the current training status (progress display) is needed in the game. In order to be able to control the progress of the patients in the exergame, feedback needs to be implemented in the game. This feedback has to be biofeedback, which records e.g. the movements or stress of the patients with sensors. The feedback used in the game should be also part of the storyline, if there is one, which would have a further motivating effect.
On the level of storytelling the most prioritized requirement was: The system should not tell a continuous story. The psychotherapists said that longer-term success would be possible through an appropriate individual division of work and recovery phases. This speaks against a strict story, as it is difficult to divide it up individually. Also some subjects said that a continuous story is not imaginable for them. “I think that would kind of distract me. Then I would listen to the story and become inactive when I listen to it” (CBP patients). On the other hand, five of the 10 test persons said that they could imagine a continuous story and would like to experience it in the VR.