Cost-effectiveness of nurse-delivered cognitive behavioural therapy (CBT) compared to supportive listening (SL) for adjustment to multiple sclerosis

The study was a two-arm, randomised, multicentre parallel-group controlled trial. Patients were recruited from MS centres in Hampshire and South London, and randomly assigned to receive either CBT or SL. Full details of the trial methods, intervention components and findings have been reported previously [10, 18].

Both interventions were delivered by general nurses specifically trained to provide eight one-on-one sessions, over a 10-week period. The sessions were delivered as a combination of two face-to-face meetings and six telephone calls.

Patients completed detailed measures at baseline, 15 weeks (end of treatment), 6 and 12 months post-randomisation with 12 months being the primary outcome point. The primary outcome was adjustment (defined as psychological well-being) measured using the General Health Questionnaire (GHQ-12) [19]. The GHQ-12 uses a Likert scoring method, where high scores indicate higher distress, and to allow for a meaningful cost-effectiveness analysis, the GHQ 12 score was reported as a change score, multiplied by −1 to get an inverted score in which higher figures denote better outcomes.

Quality of life was assessed using (EQ-5D-3L) [20]. EQ-5D-3L is a brief self-reported preference-based measure which considers five dimensions of health (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) each consisting of three levels of functioning (e.g. the levels for the pain dimension are no pain, moderate pain and extreme pain). This measure produces a possible 243 distinct health states ranging from 11111 (full health) to 33333 (worst) [21]. Value sets estimated from general population based studies were applied to the health states to produce preference-based scores between 0 (worse health) and 1 (full health). The measure also has a visual analogue scale ranging from 0 (the worst health you can imagine) to 100 (the best health you can imagine). Quality-adjusted-life-years (QALYS) were derived from transformed EQ-5D-3L scores, using the area-under-the-curve method [22].

Contacts with the CBT and SL interventions were centrally recorded. Self-reported six-month retrospective health and social services data were collected at baseline, six- and 12-month follow-up, using an adapted version of the Client Service Receipt Inventory (CSRI) [23]. To ensure we captured relevant services the CSRI was adapted based on available literature and expert guidance. Patients provided details of their retrospective use of medication, inpatient, out-patient appointments, laboratory tests and scans, emergency department, contact with community professionals (GPs, neurologists, etc.) and informal care including access to social welfare benefits.

Service use was combined with nationally applicable unit costs [24‐26] to derive total costs. Costs were measured in UK prices (£) for 2008/09, and given the one-year time horizon, there was no need to discount either costs or effects. Interventions costs were estimated by multiplying the unit cost of nurses providing the intervention by the number of sessions attended. Informal carers are not paid for their support to patients but there is still a value to this time. Informal care cost was estimated using the unit cost of a local authority home care worker as a proxy value [24]. Productivity costs were estimated through the human capital approach, which involves applying national wage rates to days off work due to illness.

Data were analysed using Stata 11 and patients were assessed using an intention-to-treat analysis. Missing costs and QALY data were imputed using a regression-based method adjusting for baseline variables costs, EQ-5D-3L scores, GHQ-12 score, and the type of MS. Non-parametric bootstrapping methods were used to account for non-normality in the distribution of cost data [27]. Outcomes and costs were presented as mean values with standard deviations, and compared between groups at baseline and 12-months follow-up.

The economic evaluation was conducted from both a health and social care, and societal perspectives. If one intervention had lower costs and better outcomes than the comparator, then it would be considered ‘dominant’. In the event of the intervention having higher costs and better outcomes, cost-effectiveness would be assessed using incremental cost-effectiveness ratios (ICERs).

Cost-effectiveness planes (CEP) and cost-effectiveness acceptability curves (CEAC) were created to address the uncertainty around points estimates of the ICERs. For the CEP plane, non-parametric bootstrapping was used to create a joint distribution of incremental costs and outcomes, and plotting these differences on a scatter plot (one axis represents incremental costs and the other incremental outcome), to show the probability of the intervention being (i) cost-saving and more effective, (ii) cost-saving and less effective, (iii) cost-increasing and more effective and (iv) cost-increasing and less effective. The probability of the intervention being cost-effective was explored through the use of cost-effectiveness acceptability curve (CEAC), which were created by calculating a series of net benefits for a range (£0–£60,000) of plausible values defined as a decision maker’s willingness to pay for an additional unit improvement of health outcomes (e.g. QALYs) [28].

48 participants were randomised to CBT and 48 to SL. Patient characteristics at baseline were broadly similar across groups (Table 1), except that the SL group had a slightly higher mean age (43.1 vs. 40.3); were more distressed (GHQ-12), disabled (EDSS scores), with slightly lower quality of life scores (EQ-5D-3L). The proportion (23%) reporting use of antidepressants was higher for the CBT group (25 vs. 22), and more than half (60.6%) had clinically significant distress levels.

There were minimal differences in service use between the two groups. Participants accessed a wide range of health and social care services (Table 2), but the most intensively used were the GP (84% at baseline) and MS nurse (82% at baseline), followed by neurologists (66%). The proportion with GP contacts had decreased by 12-month follow-up for both groups. The percentage in contact with neurologists and MS nurses was reduced over the follow-up period, with more reductions evident in the SL group for neurologists. Most participants reported the use of at least one medication (particularly disease modifying therapies) in both groups at baseline. Physiotherapists and alternative therapists had consistently low use over the entire study period for both groups.

Despite low admissions (10%), the CBT group had substantially more inpatient days at 12 months. More than two thirds (71%) reported investigations (e.g. blood tests, MRI, x-rays, CT/CAT and EEGs) at baseline, but at follow-up the proportions had decreased for both groups. The mean number of tests remained the same (2.5) for the CBT group, but had decreased (1.6) for the SL group. Almost all (99%) patients reported informal care at baseline, and while this had decreased at follow-up, the mean hours/week were not so different. The mean cost of CBT was £307 compared to £306 for SL over 12 weeks. At baseline, mean service costs were fairly similar between the groups (Table 3), but higher informal care costs for the CBT group (£4378 vs. £2903), contributed to much more societal costs at baseline compared to the SL group. Over the whole follow-up period, mean costs were higher in the CBT group. Drug costs contributed the highest share to health and social care costs while informal care added the greatest proportion to societal costs. Although the number receiving informal care were similar, the CBT group had greater intensity of use hence higher costs. From the health and social care (NHS) perspective CBT had higher mean costs at follow-up compared to SL (£7331 vs. £5026), but this difference, adjusted for baseline costs (£1610) was not statistically significant (bootstrapped 95% CI, −£187 to 3771). The difference in mean costs from the societal perspective (£2871), was also not statistically significant (bootstrapped 95% CI, −£2028 to £7793).

At baseline GHQ-12 scores were lower for the CBT group (13.98 vs. 16.40), and at 12 months both groups showed reductions in distress but the improvement in mean scores was better for the CBT group (2.69 vs. 1.97) and the difference(1.9572) statistically significant (bootstrapped 95% CI, −5.41 to −1.05) [17]. Based on the change score, CBT produced an ICER of £821/GHQ-12 score compared to SL from the health and social care perspective, indicating that for a one-point improvement on the GHQ-12 the NHS should pay £821. The ICER from the societal perspective is £1242/GHQ-12.

QALY results were also better for the intervention group at 12 months (0.6627 vs. 0.6197) but the difference (0.0053) was not statistically significant (bootstrapped 95% CI, −0.059 to 0.103). CBT was therefore more effective at improving quality of life, but expensive, yielding an ICER of £303,774 from the health and social care perspective and £541,698 from the societal perspective.

Further research in this area could be directed at designing CBT trials targeted to those who need it most, such as people with distress, as well as using alternative utility measures validated for psychological interventions in MS patients. We also know little about the cost-effectiveness of different levels of clinical expertise. In this study, senior nurses who received a two-month training course provided the CBT. It is possible that experienced clinical psychologists, although costlier, may facilitate larger treatment effects and cost savings. Finally, recent evidence [34] suggests online therapy for depression may be an effective treatment in MS. Providing minimal therapy support alongside online therapy may be a cost-effective solution.