Low back pain (LBP) is a common health complaint and a leading cause of disability worldwide.1–3 Ten to 15% of people with LBP have experienced chronic LBP lasting for longer than 3 months. Chronic LBP is a burdensome condition and is associated with social isolation, early retirement, and prolonged work absenteeism.4,5 Physical activity may reduce the risk of someone developing chronic LBP by improving physical condition, mood, and motivation.6 There is moderate certainty evidence from meta-analysis that physical activity improves absenteeism outcomes in people with sub-acute LBP (4–12 weeks), suggesting this phase may be an important time to target interventions.7 Moderate to vigorous physical activity reduces long-term disability in people with chronic LBP,8 but physical therapists have reported this can be challenging to facilitate.9

Motivational interviewing is an evidence-based counselling technique to address ambivalence towards healthy behaviour change, through relational components (the spirit of motivational interviewing) and technical components (referred to as micro-skills).10 Collaboration, autonomy, and evocation of ideas from the patient about behaviour change are facilitated through micro-skills, including open-ended questions, affirmations, reflective listening, and summaries.10 Adding face-to-face and telephone-based motivational interviewing to usual physical therapy care improves functional capacity in people with acute to sub-acute LBP.11,12 However, dedicated 1:1 consultations require additional funding and this may not be accessible to all patients. Training physical therapists to allocate a portion of usual treatment time to motivational interviewing may be more time efficient, but in isolation is unlikely to be enough to influence sustained changes in physical activity.

Smartphone applications (apps) have been used as a convenient way to deliver behaviour change interventions in healthcare settings.13 Apps incorporating the principles of motivational interviewing have increased self-efficacy and physical activity in sedentary adults.14 However, while some components of a motivational interviewing intervention for increasing physical activity are conducive to be being delivered by an app (e.g. questions can be phrased to elicit patient change talk), others (e.g. accurately responding to open ended questions) require face-to-face interactions.15 An intervention combining an app-based component with an in-person component that does not significantly detract from other physical therapy treatment modalities, may be one way to address this.

The aim of this trial was to evaluate a new motivational interviewing intervention comprising a physical therapist-delivered component and a self-directed patient app, for increasing physical activity in people with sub-acute LBP.

The trial protocol has been published.16 A mixed-methods, cluster randomised controlled trial was conducted in the physical therapy outpatient departments of 4 public hospitals in Melbourne, Australia. Hospital sites (clusters) were allocated by single block pragmatic randomisation to deliver 6 weeks of usual physical therapy or 6 weeks of the newly designed motivational interviewing intervention (Table 1). Concealed allocation was completed by an independent researcher using a random number generator (www.randomization.com). The study received ethics approval from the Alfred Hospital Ethics Committee (47/15), Eastern Health Human Research and Ethics Committee (E12-2014), La Trobe University Human Ethics Committee (E12-2014) and Monash Health Human Research Ethics Committee (15067X). The study protocol was listed on the Australian New Zealand Clinical Trials Registry before the trial commenced (12615000724572). All participants provided written, informed consent prior to the trial commencing. The trial is reported in accordance with the Consolidated Standards of Reporting Trials (CONSORT) statement for cluster randomised controlled trials17,18 and the Consolidated Criteria for Reporting Qualitative Research (COREQ)19

Patient recruitment commenced on 27 March 2017, and the final assessment was completed on 23 August 2018. The trial was finalised before meeting the recruitment target because of resourcing constraints. The flow of patient participants through the study is shown in Fig. 1. Of 58 patients screened for eligibility, 2 declined because their symptoms improved, 10 were excluded because they scored in the severe range for depression and/or anxiety on the DASS-21, and 46 were enrolled (20 in the control group and 26 in the experimental group). One patient in the control group and 5 patients in the experimental group did not complete a follow-up assessment. Two patients in the experimental group experienced a mild skin reaction to the accelerometer film and did not complete this component of the reassessment and 1 patient was unavailable for the follow-up accelerometer assessment. These data were omitted from the follow-up assessment of the primary outcome. All available data were included in the analysis.

Fig. 1.

Trial design and flow of participants through the study.

(0.45MB).

There were 78 physical therapy consultations in the control group (mean = 4.6, standard deviation [SD] 1.6) and 72 consultations in the experimental group (mean = 3.2, SD 1.80), a mean difference of 1.3 consultations (95% CI: 0.3, 2.4). Nine participants in the experimental group (35%) did not use the MiMate app at all. The average number of core modules completed over the 6-week intervention was 4.8 (SD 3.9). The average number of activity diary entries was 25.4 (SD 34.7) and the flare up module was used an average of 2.0 (SD 2.9) times.

The mean age of participants was 43.7 (SD 14.3), and the mean symptom duration at the time of the first treatment session was 30.2 (SD 14.6) days (Table 2 and supplementary material).

This trial investigated a new way of delivering motivational interviewing that combined a face-to-face component (physical therapy embedded motivational interviewing) and a self-directed patient smartphone app, MiMate. There was no between-group difference in change in physical activity at the end of the 6-week intervention. The recruitment target of 60 participants was not met and this likely contributed to the study being underpowered for the primary outcome measure (MVPA).

Improvements in LBP disability, functional capacity, and pain self-efficacy favoured the control group, with small to moderate associated effect sizes. These findings are in contrast with a previous study that showed 6 × 30-min telephone motivational interviewing consultations plus physical therapy improved functional activity in patients with sub-acute LBP, compared with physical therapy alone.11 In the current study motivational interviewing was embedded into usual physical therapy consultations and there were poor levels of compliance with the patient smartphone app. The amount of motivational interviewing delivered to patients is likely to have been less than in previous studies.11,12,42 In the current trial, patients in the control group also received more physical therapy (on average 4.6 vs 3.2 consultations). This can make findings difficult to interpret. Therefore, patients in the experimental group received less physical therapy care, and the intensity of motivational interviewing delivered may not have been sufficient to influence a meaningful increase in MVPA. A previous systematic review and meta-analysis found that brief sessions of motivational interviewing of 15 or more minutes were potentially effective for facilitating health behaviour change in people with chronic health conditions.43 However, the motivational interviewing interventions included for review were either dedicated face-to-face or group interactions. The findings of the current trial support the need for further randomised controlled trials to evaluate how to best integrate motivational interviewing into regular healthcare practice in non-counselling settings.

This study had several strengths. Physical therapists’ proficiency in delivering motivational interviewing was confirmed using a validated outcome measure. The cluster design also meant that there was a small risk of contamination between experimental and control physical therapists. Despite not meeting the recruitment target, the study was likely sufficiently powered to detect a statistically significant difference for the secondary outcome measures.

There were also some limitations. The recruitment target of 60 participants was not met and one healthcare site only recruited two patient participants, because of an unexpected decline in patient referrals for LBP. There were low levels of engagement with and use of the MiMate, which was designed to increase the amount of motivational interviewing delivered to patients. The MiMate smartphone app and online therapist portal were delivered as intended (patients were able to download it and functionality of the therapist portal was confirmed). However, it appears likely that these components of the intervention were not used as intended by most patients and physical therapists. The main app modules were designed to be accessed every 1–3 days; however, patients used this section on average only 4.8 times over the 6-week intervention and 35% did not use it at all. None of the physical therapists reported using the therapist portal to review patient completed app content. The online portal was envisaged as the conduit between the two components of the intervention and designed to assist physical therapists in planning the motivational interviewing content of consultations. Future studies may consider using motivational interviewing as part of the physical therapy training program to improve patient compliance with the app, as well as therapists' use of the online portal. Some patients reported they were unsure about the relationship between the app and physical therapy consultations. Uncertainty of purpose is a barrier to patients engaging with digital interventions for LBP.44 A series of introductory videos within the MiMate app that explain its purpose and provide examples of it being used in everyday situations may be a practical way of addressing this.

Finally, physical therapists were assessed for proficiency in delivering motivational interviewing by a 20-min face to face session with a study coordinator, who spoke about a personal health-related behaviour they wanted to change. This was not aligned with how physical therapists were taught to embed motivational interviewing into regular consultations for LBP and the extent to which physical therapists were able to achieve this remains uncertain. Audio-recording all physical therapy consultations and applying the MITI to a random selection of de-identified consultations would provide a more accurate assessment.45

It remains uncertain if training physical therapists to embed motivational interviewing into consultations, and combining this with a self-directed patient app, is more beneficial than usual physical therapy care for increasing physical activity in sub-acute LBP. Despite this, physical therapists were positive about motivational interviewing. Given the accessibility and potential cost-effectiveness of evidence-based behaviour change apps, further studies are warranted to establish the feasibility and effectiveness of the intervention. These should ensure adequate steps to optimise patient adherence and engagement with the MiMate smartphone app.