What Is the Effectiveness of Different Duration Interdisciplinary Treatment Programs in Patients with Chronic Pain? A Large-Scale Longitudinal Register Study

Round 1

Reviewer 1 Report

The article includes the results of a large-scale longitudinal register study of patients with musculoskeletal chronic pain that have followed different duration interdisciplinary treatment programs. The conclusions of the research are of importance for clinical practice in the management of patients with back and neck pain, or fibromyalgia.

I have several comments.

Materials and methods.

Intervention.

- Have all the patients followed the same physical activity/exercise program? This fact should be more detailed.

- What pharmaceutical treatments did the patients followed? Did all the patients require a pharmaceutical treatment?

- It is not clear what signifies the the duration of 8-40 hours/week. Did the intervention last 8 hours per day?

Results.

Did all the three groups (short, moderate and long interdisciplinary multimodal rehabilitation) include a similar percentage of patients with neck pain, back pain, fibromyalgia and general widespread pain?

Author Response

Please see the attachment.

Thank you.

Author Response File: Author Response.docx

Reviewer 2 Report

This is an interesting study intended to evaluate and compare the effectiveness of different duration interdisciplinary multimodal pain rehabilitation (IMPR) programs. There are few studies that examine multiple multidisciplinary pain management programs over the same period, and research addressing the effects of program ‘dosage’ are rare. As such, the study is an important addition to research in this area. There is much to be encouraged by the study methodology (pragmatic register-based effectiveness study), but there are some problems concerning the methodology/analysis and interpretation which need to be addressed. But if done so satisfactorily,

Major points

1. Methods p.2 Lines 89-92. On what basis was the grouping of short, moderate and long IMPRs made? Considering IMPR length as a continuous variable in models may have been a better approach.
2. Methods pp.3-4 Lines 135-145. The primary study outcomes concerned changes to health-related quality of life (HRQoL), in this case perceived physical and mental health as measured by SF-36. Multidisciplinary pain rehabilitation programs often specifically target maladaptive pain beliefs (for example, concerning pain catastrophizing or pain self-efficacy in CBT-based programs, or pain acceptance and psychological flexibility in Acceptance and Commitment Therapy (ACT)-based programs). Some acknowledgement of this is warranted in the manuscript, particularly the lack of evaluation of these constructs.
3. Methods p.4 Lines 180-187. The use of MCIDs across a range of measures for which baseline values for some individuals may not indicate clinically significance levels complicates interpretation of proportions improving or deteriorating. A better approach may be to consider the proportion of patients showing reliable and clinically significant improvements on outcome measures for individuals who were above and below the clinically significant thresholds at pre-treatment (e.g., Jacobson’s reliable change index (RCI) and clinically significant change criteria; Jacobson et al. 1999).
4. Results Figure 1. Can the authors clarify the difference between lost-to-follow-up and non-completion of post-intervention/Month 12 measures – the lack of post intervention data implies a not insignificant IMPR drop-out rate (approx. 20%) – or is there another reason why patients completed the programs but did not complete measures?
5. Table2, Table 3. To aid comparisons with other studies of IMPR/pain management programme outcomes, it would be enormously helpful to include a measure of effect that is independent of sample size (e.g., Cohen’s d based on marginal means).
6. Was there any evidence of clustering within the dataset according to specific IMPR clinic (seems likely)? If so, a generalized linear mixed modelling approach may better account for this (multi-level) structure and allow more complex models to be generated.
7. Results 9 Lines 260-273 Figure 3. Were the proportions of participants that improved, deteriorated or stayed the same (according to MCID) from baseline to post-treatment/12-month follow-up calculated from available data (i.e., reduced sample) at the time-points or estimated data? Clarification is needed.
8. Results p.9 Lines 260-273 Figure 3. Was there a relationship between baseline scores on measures and whether participants improved, deteriorated, or stayed the same according to relevant MCIDs?
9. Discussion p.12 Lines 400-402. More elaborate consideration of other factors potentially influencing IMDR outcomes would be helpful (e.g., role of practice of learnt strategies post-intervention, CBT with or without ACT).

Minor comments

1. Methods p.3 Lines 122-124. It is stated that ‘In Sweden, most IMPR programs are group-based’ – how many patients in the study participated in one-to-one based programs? Was this variable accounted for in analyses?
2. Results Table 1. For ‘Pain duration (months) median’ it would be helpful to also provide a range (e.g., inter-quartile range).

3. Conclusions p.12 Lines 422-424. While as a group there are effects indicating significant improvement over the course of IMPR treatment and beyond, it is not clear from the data that the majority of patients reported significant improvement – this sentence requires amendment.
4. Discussion pp.10-12. The bullet-point format used in the Discussion is unusual. Prose format is a more standard approach.

References

Jacobson NS, Roberts LJ, Berns SB and McGlinchey JB. Methods for defining and determining the clinical significance of treatment effects: description, application, and alternatives. J Consult Clin Psychol. 1999; 67: 300-7.

Author Response

Please see the attachment.

Thank you.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

All my comments were addressed.

Author Response

Thank you.

Reviewer 2 Report

There has been an improvement of the manuscript according to changes made in response to the recommendations of the reviewers, with greater clarity provided around the Methods and Results. There are some minor points (below) - once addressed, the manuscript could be published in the Journal of Clinical Medicine.

1. Methods pp.4-5 Lines 187-194. Although the authors acknowledge in their reply letter that the MCID as cut off-criteria for clinical change, improvement, and deterioration has it shortcomings, it would be pertinent to also do this in the manuscript. Specifically, to make the point (perhaps in Discussion/Limitations) that the use of MCID does not in itself indicate whether an individual shifted from a clinically significant to a non-clinically significant level (or vice-versa).
2. Results Figure 1. The authors clarification of the difference between lost-to-follow-up and non-completion of post-intervention/Month 12 measures is helpful, although comment on the potential impact of the (likely significantly) higher non-completion of post-intervention measures in the ‘moderate IMPR’ group is warranted.
3. Table 2, Table 3. Although the authors express concerns about the reliability of effect size estimates, providing a measure of the magnitude of (group) effects independent of sample size (e.g., Cohen’s d based on marginal means) for outcome measures would be helpful, even if only as a supplementary table/figure.
4. Discussion p.10 Lines 302-304. While as a group there are effects indicating significant improvement over the course of IMPR treatment and beyond, it is not clear from the data that the vast majority of patients reported significant improvement as stated – the MCID data suggests otherwise (approximately 50% according to specific measure) – as such, this sentence requires amendment.
5. Discussion p.12 Lines 401-403. The added statement ‘Practicing and incorporating learnt strategies from the IMPR in real life is by this logic likewise ongoing after the intervention has ended’, while important, is difficult to understand – please amend.
6. Discussion p.13 Lines 428-430. The added statement ‘…it is especially of importance to perform further subgroup analyses…’ may read better as ‘‘…it will be especially important to perform further subgroup analyses…’.

Author Response

Please see the attachment.

Author Response File: Author Response.docx