Economic evaluation
Table
3 presents the results of the economic analysis, detailing the costs, outcomes and cost-effectiveness (in terms of cost per number of participants achieving the target of a weekly step increase of ≥15,000 steps) associated with "usual behaviour", minimal and maximal intervention.
Table 3
Cost-effectiveness results
"Usual behaviour" | £ - | 4 | £ - | - | - |
Minimal intervention | £ 735 | 12 | £ 735 | 8 | £ 92 |
Maximal intervention | £ 1,326 | 13 | £ 591 | 1 | £591 |
The results suggest that maintaining "usual behaviour" (i.e. no intervention), as assessed by the waiting list control over 12 weeks, leads to four participants achieving a weekly step increase of ≥15,000 steps at, an assumed, zero cost. Minimal intervention results in an additional eight participants achieving the target at an extra cost of £735. Thus, the cost-effectiveness of the minimal intervention compared to "usual behaviour" is an additional £92 per additional target achiever (= 735/8). Maximal intervention results in 13 participants achieving the target (one more than with the minimal intervention) at a cost of £1,326 (£591 more than the minimal intervention). Thus, the ICER associated with the maximal intervention, compared to the minimal intervention, is £591 per additional target achiever (£591/1).
These results suggest that either intervention (minimal or maximal) may be considered cost-effective. The decision between which of the two to adopt would depend on the societal value placed on each person achieving the target. For example, when the value of a person achieving the target is rated between £92 and £590, then the minimal intervention would be considered cost-effective. In contrast, if the value placed on a person achieving the target was £591 or more, then the maximal intervention would be considered cost-effective. However, if the value placed on a person achieving the target was less than £92 neither intervention would be considered cost-effective.
In the UK, standard thresholds used to determine cost-effectiveness are based on a societal value for a QALY (λ). These values are typically in the region of £20,000-£30,000/QALY [
16]. A sensitivity analysis was carried out to assess how many QALYs would need to result from each person achieving the target for each of the interventions to be considered cost-effective according to these standards (i.e. the weight that would need to be attached to each target achiever for the ICER of the intervention to fall below these standard values). This is determined for each intervention by dividing the ICER associated with that intervention by the standard level of cost-effectiveness required (λ).
Thus, in order for the minimal intervention to be considered cost-effective at a level of £30,000/QALY, achieving and maintaining the target of ≥ 15,000 additional steps per week over 12 months would need to improve each person's lifetime QALYs by at least 0.0031 (= 92/30000). If achieving and maintaining the target over 12 months increased each person's lifetime QALYs by more than 0.02 (= 591/30000), then the maximal intervention would be considered cost-effective against this standard threshold. This level of increase in QALYs equates to an increase in survival (in full health), as a result of the maximal intervention, of 7.3 days over a lifetime (= 0.02*365), or 1.1 day over a lifetime for the minimal intervention (= 0.0031*365).
Qualitative evaluation
The data from the four focus groups with participants (FG) and the six semi-structured interviews with research staff (R) were combined and analysed together, and are presented below in terms of three themes representing: 1) support, 2) monitoring and 3) practical issues.
Support
Throughout the project, two researchers were primarily responsible for delivering the intervention and co-ordinating assessments. Each researcher took responsibility for half of the participants and maintained regular contact for up to 12-15 months:
We got to know them, they got to know us. We asked about their family etcetera (R1)
Participants were very positive about the support they received from these two researchers. So much so, that as the quote below shows, they were anxious about what they would do when the support stopped:
If I'm not in the project, I think I'll lose motivation completely. I don't think I'll be able to continue walking if I'm not in the project (FG 2, male, high adherer)
Indeed, although the quantitative outcomes showed that participants maintained increased walking after 12 months in comparison to baseline [
8,
22], in focus group discussions a number of participants spoke of a lack of motivation, with some also reporting the strategies they had used to overcome this:
Once I'd handed in the book and didn't have the book anymore, that sort of took away some of the pressure and my walking dropped off (FG 2, female, high adherer)
I think writing down what you've done is really useful. Since we've stopped I've been writing it down in a chart I've drawn myself (FG 3, female, high adherer)
Monitoring
The majority of respondents felt that the step-count provided by the pedometer provided useful feedback which supported and encouraged them:
I think the pedometer was really useful at the beginning because you got tuned into it and checked it and I realised that my days at home and days at work were really quite different so I needed to make a special effort on my days off (FG 4, female, high adherer)
When initially designing the study, concerns were expressed by the research staff about the level of participant burden, particularly in terms of measurement of health outcomes such as body mass and cholesterol (which necessitate physical measurements and blood being taken). In fact, for those who participated in the study, these health checks were considered an incentive for their initial and continued involvement in the study:
I wanted to do it because I could get my weight monitored and so on; so I could see if it was actually having any impact (FG 4, female, high adherer)
I really would have liked to have results every time we met. That's the main reason I took part ((blood pressure etc.)) (FG 4, female, high adherer)
Practical issues
Many of the participants said that walking appealed over other forms of activity because it was cost-free, could be undertaken alone without generating feelings of self-consciousness and could fit easily into their daily routine:
I like [walking] because I can do it by myself and I don't have to embarrass myself at the gym. I can afford to do it because it doesn't cost anything and I can do it when I'm going to the shops or work (FG 2, female, high adherer)
In the first pair of focus groups (taking place shortly following the 12 week intervention), all but one of the participants had achieved their targets and they had done this either by making time for walks during the day ("I try to take a walk every day" (FG 1, male, high adherer)), or by incorporating it into their daily activities:
I haven't set out to walk everyday; instead I've tried to incorporate it into what I usually do. So rather than taking the bus to ((Place)), I'll now walk and it means taking much more time to actually get there (FG 1, female, high adherer)
Participants also mentioned the physical, social and emotional benefits of increasing walking:
Yes, when I drop off my daughter and go for a walk I feel invigorated. It makes you wonder why you don't do it more (FG 1, female, high adherer)
On my way home I park up at the Botanic Gardens and go for a walk. And I've seen things I didn't know about. I didn't know there was a disused railway track in the Botanic Gardens! It's a great way of getting out there and seeing things that I hadn't done before and meeting the gardeners you know, when you stop for a breath (FG 1, female, high adherer)
Respondents mentioned a number of barriers to increased walking, such as bad weather ("I hit a rough patch when we had that wet period", FG 1, male, high adherer) and boredom, especially amongst those who had tried to initiate a walk during the day, outside their usual daily activities. In addition, those who'd tried to incorporate walking into ordinary daily activities, like walking to the shops or to work, mentioned barriers such as lack of time and practical issues such as carrying shopping, laptops etc.:
I found it quite hard walking to work at times. When I have meetings or whatever and I have a laptop to carry, I'm wearing a suit and heels, I just can't do it. So I jump in the car. I'm still trying to take the stairs at work, but more often than not I drive to work now. I mean, it sounds very vain, but I straighten my hair every morning and if it's bad weather, or even a bit damp and I walk, my hair is a frizzy mess by the time I get to work (FG 3, female, low adherer)