3.4. MINIMIZACION DEL SISTEMA
3.4.2. SEGUNDA PRUEBA
approach interventions
We gained some insight into how CBA might work in LBP. Changes in intermediary outcomes were consistent with a hypothesis that CBA reduces fear avoidance and improves pain self-efficacy. However, within the quantitative data set, no solid inference can be made about a mechanism of effect as there is no information on the temporal sequence of changes. The qualitative data set provides further data to support the hypothesis that recognition of negative thoughts and behaviours is a key to enabling recovery, and the importance of re-establishing routine physical, leisure and occupational activity.
TABLE 54 Cost-effectiveness data from trials testing interventions for back pain in primary care
Intervention Comparator Perspective, time frame N, Cost/cost-effectiveness Whitehurst
2007165 Brief pain management programme addressing psychosocial risk factors
Physiotherapy (mobilisation, manipulation and soft tissue treatment)
Generic health care; N = 299; TF = 1 year
Brief pain management (CB) not cost-effective; ICER = £2800 for physiotherapy Jellema
2007167 Minimal intervention aimed at psychosocial factors Usual care NHS; MIS = 116; UC = 134; TF = 1 year
Inconclusive
van der Roer
2008165 Intensive group training – physiotherapy + behavioural component
Guideline individual physiotherapy sessions
Societal; N = 102;
TF = 1 year ICER = €500 to €5150 depending on assumptions Rivero-Arias
2006166 Active management advice Physiotherapy NHS; TF = 1 yearN = 286; ICER = £3010 BEAM 200494 Exercise
Spinal manipulation Manipulation and exercise
Active management
and The Back Book Health care; N = 1287; TF = 1 year AM + exercise dominated; AM + manipulation + exercise £3800 BC + manipulation £8700 Ratcliffe
2006168 Acupuncture Usual care Societal; TF = 2 yearsN = 241; ICER = £4241
BC, best care; ICER, incremental cost-effectiveness ratio; MIS, minimal intervention aimed at psychosocial factors; TF, time frame; UC, usual care.
95 The relationship with the therapist was raised by a
number of individuals who were interviewed. Most comments were in a positive light, although on occasion, this was not the case. However, within the quantitative analysis, we found very little evidence that variation in treatment outcome was influenced by individual therapists. There are a number of potential explanations. Although there was quite a large number of therapists involved in the delivery of the intervention, in practice a core of therapists delivered to a large number of groups. As a consequence the variance structure was complex and modelling required extending current methods and in some instances failed to achieve a good fit. Group and therapist effects were to a degree confounded. We had structured the intervention purposefully so that the same therapist would be responsible for delivering all assessments and sessions within each cycle of CBA. Additionally, each group was discrete. Only on rare occasions did a participant swap between group/therapist. As a consequence, the effects of participant, group and therapist are challenging to differentiate.
We measured the competence of most therapists in delivering the intervention by audio-taping sessions and assessing competence against prespecified and internationally agreed criteria. Although competence varied between therapists, therapist effects were still not influential. Possible explanations are the structured approach to the intervention in both the participant training manual and the format of the group sessions, which means that participants may be exposed to cognitive training aspects regardless of the ability of the therapists to use skills such as Socratic questioning.
Previous qualitative research has highlighted the potential importance of ‘group’ effects in determining outcome, and the therapeutic effect of both talking with people with a similar condition and drawing comparison with others with a similar diagnostic label.169 Similar themes emerged from the qualitative analysis, but the quantitative analysis mitigates against group effects as being a major factor in explaining how the intervention works. We made no attempt to group participants of similar backgrounds together (for example men and women), meaning that the variability in participant profile was high in all groups.
We prespecified a per protocol analysis to explore dose dependency. We hypothesised that individuals would need to attend the assessment and three sessions to ensure the main messages
of the intervention were embedded. Compliance with the intervention at this prespecified level was reasonable (65%), but effectiveness was not influenced by compliance in the way that we had measured it.
We ran a number of subgroup analyses to
determine whether pain severity, duration or fear avoidance at baseline were predictors of treatment outcomes at 12 months. These analyses were all prespecified and based on stringent interpretation of interaction tests to minimise false-positive findings. Nevertheless, the findings should be treated as exploratory. The factors which emerged were fear avoidance at baseline and then impact was seen only in MVK (disability) scores – those people who showed least fear avoidance at baseline had larger responses to the intervention. Also, pain severity at baseline had a weak association with treatment outcomes measured by the RMQ at 12 months – the treatment effect measured by the RMQ may be larger in those with moderate pain at baseline. Both observations may be useful for generating hypotheses for future research, but should be used with caution in informing health technology appraisal.
Within one cluster there were several general practices that had a high proportion of people from minority ethnic groups. These practices were also based in areas of high socioeconomic deprivation. Participants who were referred into groups from these practices had a lower rate of attendance on the programme (50% compliance compared with 67% in the trial overall). The therapists involved in facilitating these programmes reported that although there was enthusiasm to attend, participants were often unable to attend because of difficult work and social situations, such as child-care cover. Even though these practices had high numbers of people from ethnic minorities, it became apparent that within the trial it was not practical to be able to fill a group with participants who spoke the same language and to be able to find and train enough therapists to cover languages that might be used. We considered using a translator but felt that the discursive nature of the group intervention would have been compromised as the therapist would not have been easily able to facilitate discussion between group participants. As a result of the low number of health professionals from ethnic minority backgrounds, these issues are likely to be present even outside a trial environment and a flexible approach will be needed to deliver a CBA in some populations. It may be that alternative
programmes requiring fewer visits overall may overcome difficulties in attendance. In addition, to meet cultural or language needs, the intervention may need to be run on a one-to-one basis or via different mediums such as more comprehensive written materials, video format or the use of internet interventions that seek to teach the same self-management skills.