Almazrou, Saja
(2018)
Describing the characteristics, treatment pathways and outcomes of people with chronic low back pain managed by a pain management Service in Nottingham and generating indicative estimates of cost-effectiveness.
PhD thesis, University of Nottingham.
Abstract
Background: Chronic low back pain (CLBP) is a highly prevalent condition that has substantial impact on patients, the healthcare system and society. Its aetiology is complex and the condition can be exacerbated by many psychological, physical and social factors. Pain management services (PMS), which aim to address the complex nature of back pain, are recommended in clinical practice guidelines to manage CLBP. Although the effectiveness of such services has been widely investigated in relation to CLBP, the quality of evidence underpinning the use of these services remains moderate. Given that these services are resource intensive, evidence is needed to determine their cost-effectiveness.
Aim: This study aims to describe the patient characteristics, clinical outcomes and healthcare resource use of people with CLBP in a community-based pain management service (PMS) in Nottingham to derive an indicative estimate of the cost effectiveness of PMS compared with standard care (SC).
Methods: The study followed the Medical Research Council (MRC) guidance for evaluating complex interventions. The MRC suggest conducting developmental and observational work before evaluating complex interventions on a larger scale. Therefore, this PhD research includes a service evaluation study, which was conducted in two community-based PMS in Nottingham. This was followed by a systematic review of the cost effectiveness of a PMS in CLBP. Finally, a decision analysis model was developed to assess the cost effectiveness of PMS compared with SC.
In the service evaluation study, newly referred people with CLBP who provided written consent were included. Participants provided information on health status and healthcare resource use using postal questionnaires and diaries at baseline and then three and six months after recruitment. The outcome measures were the Brief Pain Inventory (BPI), the Roland Morris Disability Questionnaire (RMDQ) and the EuroQoL (EQ-5D-3L).
In the systematic review, electronic searches were conducted in clinical and economic databases from their inception to August 2017. Full economic evaluations, undertaken from any perspective, conducted alongside randomised clinical trials (RCTs) or based on decision analysis models were included. The Cochrane Back Review Group (CBRG) risk assessment and the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist were used to assess the methodological quality of eligible studies. These studies informed the development of an economic evaluation based on a decision analysis model to compare PMS with SC. Costs per extra quality-adjusted-life-year (QALY) were calculated from the UK National Health Service (NHS) England perspective using a lifetime horizon. Transition probability, utilities, healthcare resource use and costs were obtained from the service evaluation study and the published literature.
Results: In the service evaluation study, 32 people were recruited over 10 months. The mean age was 58.8 years with an equal distribution of both genders. The dropout rates were 21% and 25% over three and six months respectively.
Disability was measured using RMDQ (with a score range between 0-24), where higher scores mean more disability. The mean score at baseline was 13.5, after three and six months the means were 11.9 and 11.1 respectively. The BPI was used to measure pain intensity and interference. The scores ranged from 0 to 10, where higher scores mean more pain. The mean score for pain intensity was 5.9 at baseline, followed by a mean of 5.5 and 5.6 at three and six months respectively, whereas pain interference was 5.9 at baseline, followed by a mean of 5.2 at three and six months. As for the EQ5D-3L, higher scores in EQ5D means better health states. The mean score was 0.38 at baseline and, after three and six months, the scores were 0.46 and 0.40 respectively. The mean number of health visits per patient between baseline and three months was 4, whereas between four and six months the mean number of visits per patient was 2.9.
In the systematic review, five studies fulfilled the eligibility criteria. The PMS varied significantly between studies in terms of the number of treatment modalities, intensity and the duration. The PMS was compared with either standard care, which varied according to the country and the setting or with two different surgical interventions. In this review, three out of five studies had a high risk of bias based on the design of the randomised controlled trials (RCTs). In addition, there were limitations in the statistical and sensitivity analyses in the economic evaluations. Therefore, the results from this systematic review need to be interpreted with caution. Finally, the indicative economic evaluation showed thatthe PMS was both more effective and more costly compared with SC. The mean incremental cost effectiveness ratio (ICER) was £761.43 and £706.98 per quality adjusted life years (QALY) gained in the deterministic and probabilistic analyses, respectively. At a ceiling willingness to pay (WTP) of £20,000, the PMS reaches a 51% probability of being cost-effective. This suggest that there is 51% probability that the PMS is both more effective and less costly. The incremental net monetary benefit generated a mean of £7884.07, indicating that the PMS is cost-effective compared with the SC at a WTP of £20,000.
In the sensitivity analysis, the results were affected by changing the utility score for severe pain and increasing the initial cost of the intervention. In the scenario analysis, the incremental cost and QALYs were in favour of the PMS for people with severe pain at baseline. The probability of the PMS being cost effective for people with severe pain was 54%. In addition, the sustained reduction in treatment effect reduces the PMS probability of being cost effective to 48%. Finally, using the two months’ data to generate the transition probabilities demonstrated that PMS dominates the SC and the probability of the PMS being cost effective was 58%
Conclusion: Community-based PMS have the potential to improve functional disability and pain interference for people with CLBP in primary care by providing well-timed access to a specialised pain management team, ensuring effective use of pain medicines and streamlining the treatment pathways based on the individual patient’s needs.
A systematic literature review highlighted inconsistent evidence supporting PMS. The cost effectiveness studies included in this systematic review were alongside RCTs with a maximum follow up period of two years. As a result of the limitations of this type of economic evaluation, a decision analysis model was developed in order to assess the life time effectiveness of PMS compared with SC.
The decision analysis model showed that PMS is more effective and costly compared with SC in the base case analysis; however, changing the source of transition probabilities from 12 months to two months demonstrated that PMS dominated SC, providing the potential for PMS to be cost-effective if high quality research is conducted to reduce the uncertainty around transition probabilities. The results were also sensitive to change in the utility score for severe pain, the initial cost of the PMS and using the PMS for people with severe pain at baseline. Therefore, further information is needed to assess the uncertainties in these parameters to provide a more robust estimate of the cost-effectiveness of PMS compared with SC.
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