Study identification

Through the systematic literature search, a total of 459 studies were identified. Duplicates (n=151) were removed and the title and abstract were assessed for the remaining 308 studies. Of the assessed studies, 136 (44%) were excluded as they did not deal with LBP. An additional 149 studies (48%) did not concern specific strategies aimed at implementing LBP guidelines in primary care. Furthermore, 13 studies (4%) were excluded, as these were not based on randomised clinical trials, and seven studies (2%), as these were not economic evaluations. In total, 305 studies (99%) were excluded based on title and abstract, leaving no more than three studies (1%) eligible for full-text screening and inclusion. No additional studies were identified through a search of the bibliographies of the included studies. Figure 1 is a depiction of this process.

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Figure 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram of study selection.9 LBP, low back pain; RCT, randomised controlled trial.

Study description

The included studies12–14 compared two or more different strategies for implementing guidelines on LBP management in primary care (table 1).

In the study by Mortimer et al,12 a cost-effectiveness analysis was carried out alongside a cluster randomised controlled trial. To increase Australian general practitioners’ adherence to the LBP guidelines, a multifaceted and theory-based implementation strategy (IMPLEMENT) was developed. The hypothesis was that the IMPLEMENT intervention, when taking into account reductions in health service use, would be cost-effective compared with standard dissemination. The intervention consisted of two facilitated interactive workshops concentrating on two key messages from the guidelines. The first workshop focused on reducing X-ray referrals, as these are rarely beneficial, and how to handle patients with X-ray seeking behaviour. The second workshop centred on the importance of patients remaining active to reduce pain and disability. For the primary outcome, the number of X-ray referrals, the IMPLEMENT intervention dominated standard dissemination when excluding development costs. However, from a healthcare sector perspective, >95% probability of cost-effectiveness could not be achieved.

The study by Becker et al13 is likewise a cost-effectiveness analysis carried out alongside a cluster randomised controlled trial. In the clinical trial, two different implementation strategies were compared with the usual strategy of dissemination. In the first intervention group ‘Guideline Implementation’ (GI), the implementation strategy consisted of physician education, where the general practitioners were trained in using the LBP guideline. In addition to physician education, the implementation strategy in the second intervention group ‘Guideline Implementation and Motivational Counselling’ (GI+MC) consisted of motivational counselling by practice nurses, who had a 20-hour training course in how to motivate patients with LBP for physical activity. In the German setting, both interventions appeared less costly, when excluding implementation costs, and more effective for the primary outcome functional capability. From a societal perspective, the probability of GI being cost-effective compared with dissemination was 97% at a threshold value of €67 per point on the functional capability scale, while there was a 99% probability at €99 when comparing GI+MC with dissemination.

Hoeijenbos et al14 undertook a cost-utility analysis conducted alongside a clinical trial. The aim of this economic evaluation was to evaluate the cost-effectiveness of an active implementation strategy aimed at physiotherapists working in primary care compared with dissemination. The active implementation strategy featured a training session, where the LBP guideline was explained as well as discussed with the physiotherapists, followed by special skills practice. For the following 4 weeks, the physiotherapists had to practise using the guideline after which a second session was conducted, where experiences and problems, if any, were discussed and the physiotherapists received feedback on their current management of patients with LBP. Since no significant difference in either costs or effects was found between the intervention and the control groups, no assessment of the cost-effectiveness of the active implementation strategy was made.

Assessment of quality

Application of the CHEC list indicated that all three studies were of moderate methodological quality (table 2).

Both Mortimer et al12 and Becker et al13 clearly described the characteristics of the study population (item 1). Mortimer et al12 failed to include patients in the clinical trial, necessitating a departure from the planned analyses. This entailed that the general practitioners became the study participants and as a reference is made to the analysis of the effectiveness,17 this item is categorised as fulfilled. Hoeijenbos et al,14 however, received a ‘no’ on this item, as no eligibility criteria were described for the study population and no reference was made for additional information. Moreover, Hoeijenbos et al14 received a ‘no’ on item 3 concerning a well-defined research question, because, in addition to clearly identifying the alternatives compared, the research question should also state the population.11 With regard to identifying, measuring, and valuing relevant costs in accordance with perspective (item 7–9), only Mortimer et al12 successfully met all three criteria. Item 16, which is centred on whether the conclusion follows from the data reported, was only covered by one study,14 while only Mortimer et al12 addressed any ethical or distributional implications (item 19).

Assessment of transferability

The first step in assessing the transferability of the included studies to a Danish setting was to apply the three general knockout criteria. A review by Koes et al19 has shown that guidelines on managing LBP in primary care are quite similar over a range of countries, including Australia, Germany and the Netherlands. Hence, all studies12–14 pass the first two general knockout criteria. Application of the third general knockout criterion is, however, not as straightforward.

Although the study by Mortimer et al12 was evaluated as being of moderate quality using the CHEC list, it had to deviate from the planned analyses20 and use an intermediate outcome. This is associated with several limitations and results should be interpreted with caution and, furthermore, precludes comparison with the other studies included. On these grounds, the study is considered not to pass the third general knockout criterion.

Becker et al13 likewise have some methodological challenges influencing the transferability assessment. This is primarily related to the lack of results presented, including consumption of resources, valuation and effects. Only incremental cost and effect are presented. Furthermore, the base case ICER does not include implementation costs and is based on complete case analysis, possibly introducing selection bias. Adjusting for baseline difference in costs and clustering of data is done in a sensitivity analysis and presented only in an incremental cost-effectiveness plane showing an estimated ICER close to zero. Since the authors may provide further information or a simple adjustment based on purchasing power parities could be carried out, it is relevant to proceed with the 14 specific knockout criteria (table 3).

The study by Hoeijenbos et al14 differs from other studies, as the implementation strategy is aimed at physiotherapists working in primary care. Since the Danish guideline on management of LBP in primary care is also aimed at physiotherapists,3 it is relevant to evaluate whether it would be more cost-effective to increase their adherence to the guideline as neither general practitioners nor physiotherapists have high adherence.21 Application of the 14 specific knockout criteria are shown in table 4. Lack of accordance in the approach to productivity cost estimation between the Netherlands and Denmark increases the risk of a biased CER. The transferability of lost productivity might, according to Welte et al,7 be improved by adjustment of the resource valuation.

On the basis of the transferability assessment, both the costs from Becker et al and Hoijenbos et al may with adjustments be transferable, with caution, to a Danish setting. However, the model of Welte does not pay much attention to effectiveness, which raises issues in the assessment of the transferability of these two studies. In Becker et al's study, only incremental effect at follow-up was reported, while in Hoijenbos et al's study no final follow-up effect was reported. This renders adjustment of foreign utilities impossible.