A randomized controlled trial investigating effects of an individualized pedometer driven walking program on chronic low back pain

A community-based, single blinded randomized clinical trial recruiting adults with CLBP residing in the Canadian province of Saskatchewan. Recruitment took place from April 2015 to December 2016 with full 12 month follow-up completed by January 2018. All methods were carried out in accordance with relevant guidelines and regulations. Ethical approval was granted by the University of Saskatchewan Biomedical Ethics Board (#14–218) and the trial was registered with the United States National Institutes of Health Clinical Trails registry NCT02284958 (27/10/2014). Written informed consent was obtained from all participants.

Recruitment strategies involved posters, flyers, clinical and public notice boards, newspapers, and electronic bulletin boards to inform potential participants either receiving clinical care for this condition or those managing on their own. Potential participants were screened for inclusion eligibility in the following manner. Firstly by the research assistant, where ability to physically participate in a walking program was evaluated using the physical activity readiness questionnaire (PAR-Q+) [24]. Any participant answering yes to one or more questions on the PAR-Q+, was advised to consult with their primary healthcare provider to obtain physical clearance prior to confirming study participation. Secondly by a research physiotherapist, with 22 years of musculoskeletal clinical experience, who undertook a clinical history focused on participants meeting inclusion criteria and determining whether any exclusion criteria were present. If eligible, participants provided written informed consent and completed a 1 week (minimum of 5 days) pedometer trial in order to determine mean daily baseline step count prior to randomization. Although our initial protocol set an inclusion threshold of < 7500 mean daily steps [25] a number of potential participants, who had a greater recorded mean daily step count, were keen to participate in the study and thus a pragmatic decision was made to include them if they met all other inclusion criteria. Following this decision to remove the step count threshold, 53 participants included in the study had a recorded mean daily baseline step count of ≥7500 steps. All participant meetings with both the research assistant and research physiotherapist took place within the administrative and clinical evaluation facilities of the Canadian Centre for Health and Safety in Agriculture at the University of Saskatchewan.

Males and females aged 18 years or over, experiencing low back pain (i.e. between the 12th costal margin and gluteal fold with or without associated leg pain) persisting for a minimum of 3 months, and capable of participating in a walking program [25].

Spinal surgery in the past 12 months; evidence of nerve root, spinal cord, or cauda equina compression; severe spinal stenosis indicated by signs of neurogenic claudication; grade 3 to 4 spondylolisthesis; fibromyalgia, or systemic/inflammatory disorder; as well as any other current lower extremity musculoskeletal injury or contraindication to increasing physical activity (PA) levels. The latter included any medical condition limiting exercise tolerance or pregnancy [25].

Following successful completion of screening, all participants recorded baseline outcome measures (described below) and met individually with the research physiotherapist for education and advice regarding self-management and the benefits of staying active. The information was standardized using ‘The Back Book’ [26, 27] encouraging a graded return to normal activities, addressing the nature of LBP, correcting unhelpful beliefs, and emphasizing the need to use prophylactic pain control medication to allow activity [28, 29].

Following receipt of this standard package of education and advice, each participant was randomly allocated into either the standardized care group (SG) or the walking group (WG) using a minimization allocation with a 2:1 ratio to the treatment/control arms. Group allocation occurred by the participant selecting one sealed, plain, opaque envelope containing the computer generated randomized allocation from a container of identical envelopes that were prepared by a research administrator independent to recruitment and independent to the meetings with the physiotherapist. The sealed opaque envelopes were sequentially numbered and when an envelope was chosen this identifier was allocated to the participant clinical record used by the research physiotherapist and the research assistant. As self-management precluded double blinding, only the assessor for outcome measurements was blinded to group allocation. The structure and reporting of this trial was guided by the CONSORT statement for clinical trials [30].

Participants randomized to the SG having received the standard package of education and advice were then followed up at 12 weeks, 6 and 12 months to record outcome measures for comparison to baseline. As pedometer driven walking has been shown to be a safe and effective behavior change tool for facilitating increasing physical activity in inactive adults [31] participants in the WG were prescribed a personalized pedometer-driven walking program wearing a Yamax DigiWalker CW-701™ pedometer [30] for a minimum of five consecutive days per week during the 12-week intervention, similar to the B2A intervention ([17, 18]. This device demonstrates excellent accuracy (r = 0.98) and high reliability (ICC = .37–.99) when walking at different speeds and on varying surfaces [32, 33]. The research physiotherapist phoned each participant at a prearranged time, each week, to discuss progress, document mean daily step count (as recorded in diaries) for the previous week, and negotiate a new daily step target for the subsequent week. In this way the walking program was tailored on a week by week basis to the individual, with outcome measures also recorded at 12 weeks, 6 and 12 months for comparison to baseline measures for within and between group comparisons. In order to verify the consistency and fidelity of the walking intervention a member of the research team observed the delivery and manner of the research physiotherapist interacting with randomly selected participants at both baseline and at 8 weeks.

A power calculation identified the need to recruit 174 participants for 80% power to detect an 8-point mean difference (sd = 15.3) between groups in levels of disability, as recorded by change in the Oswestry Disability Index (ODI) following the 12 week intervention. As we anticipated a 15% drop-out at the end of the 12 week intervention our aim was to recruit 200 participants.

Outcome measures - previously described in detail in the protocol manuscript [25].

Primary Outcome

Secondary outcomes

Adherence to the walking intervention

Baseline anthropometric and outcome measures for both groups are descriptively reported and statistically compared. Mean and 95%CI for outcome measures at each time point for both groups are presented descriptively. Mean outcome change scores (with 95%CI) are presented for both within and between group statistical comparisons. Multi-variable post-hoc sensitivity analyses are also presented for change in ODI for self-reported moderately disabled (baseline ODI ≥21) participants; as well as for change in ODI in participants whose daily baseline step count was < 7500 steps. Student’s t-test and Wilcoxon non-parametric tests are used to compare normally and non-normally distributed continuous variables, respectively between groups. To compare categorical variables between groups, Chi-square or Fisher’s exact test have been used as appropriate. Mixed-effects models of repeated measures have been fitted to compare changes of primary and secondary outcomes within and between groups at each visit from baseline. In these models the intercepts indicate average group effect when predictors/independent variables are set to zero (i.e. average effect without the influence of any covariate/independent variable). Multiple imputation has been performed using PROC MI in SAS for missing data in the intention to treat analysis [40]. A p-value of less than 0.05 was considered as statistically significant (two-sided). All statistical analyses were done using SAS 9.4 (SAS Institute Inc., Cary, NC, USA).

Following a 20 month recruitment strategy 241 people with CLBP expressed initial interest in taking part in the study. After screening, 174 participants (104 females and 70 males) met the inclusion criteria and formally consented to take part. At 12 weeks 21% (n = 37) of participants had withdrawn; at 6 months 34% (n = 60); and at 12 months 44% (n = 77).

The Consort diagram (Fig. 1) demonstrates the flow of participants throughout the trial. Of the 52 individuals who declined to enroll, 29 did not attend their scheduled first or second appointment and could not be contacted for follow up. Other reasons for declining enrolment included time and family commitments, other health issues, sought treatment elsewhere, or not interested after reading the study information. For participants who did not complete the study, the majority were lost to follow up at one or more time points and did not provide a reason for withdrawal (n = 71). If the research assistant was able to contact the participant (13 out of the 71 participants who were lost to follow up; 8 from the WG, 5 from the SG), the most common reason reported for withdrawal was lack of satisfaction with the treatment, follow up procedure, or randomization to the control group. In the weekly phone calls between the WG participants and the research physiotherapist opportunity was made available for participants to report any adverse events from the walking intervention. At the completion of the 12 week intervention no adverse events had been recorded.

Table 1 provides baseline data for personal, anthropometric and outcome measures for all participants and presents a statistical comparison of these data for both WG and SG. The only statistically significant between group differences (P < 0.05) noted were for the EQ-5D-5L quality of life and the Physical Activity Self-efficacy Scale measures. Across all participants in the study mean baseline ODI score was 20.8 (SD 11.1) and mean baseline daily step count was 6193 (SD 2848) steps.

Table 2 shows the mean scores (+/− 95%CI) for each outcome measure at each time point for both the SG and WG.

From the perspective of adherence, participants in the WG significantly increased their daily step count over the 12 week period of the intervention by an average of 2140 (SD 2894) steps (34% increase from baseline). Change in group mean weekly step count (+/− 95%CI) is presented in Fig. 2 demonstrating a marked increase at Week 1 and a consistent but more gradual increase from week 1 to week 12.

Table 3 displays the results of the multivariable mixed effects model comparing the WG to the SG for change in all outcomes at all time points from baseline to 12 months. For the ODI primary outcome the results show that both groups improved significantly over the 12-week intervention. Greater changes in the ODI scores in favour of the WG at both 6 months (3.3) and 12 months (3.1) did not meet statistical significance.

There were significant reductions in the FABQ and its two subunits for work and physical activity for both groups at each time point with a higher change score observed in the WG. However the between group differences did not meet statistical significance. Despite a higher change score improvement for the EQ-5D-5L quality of life measure noted for the WG there was no statistically significant between group differences.

Although there was an observable increase in IPAQ (377.7 mets/min) score above baseline measures for the WG at the 12 week time point the increase was not statistically significant. For the IPAQ, BBQ and Self Efficacy scale there were no significant within or between group changes from baseline at the 12 month time point.

Post hoc sensitivity analysis of participants whose baseline ODI ≥ 21 (classified as moderately disabled), demonstrated a statistically significant 13.6 (p < 0.0001) within group ODI reduction at 12 months for the WG and a 7.1 ODI difference compared to the SG (p = 0.01), however this between group effect was not observed at 12 weeks and 6 months. No other post hoc analyses were undertaken for ODI thresholds or for secondary outcome measures. A further post hoc sensitivity analysis for comparative between group changes in the ODI focused on participants with a mean daily step count of < 7500 steps. When using this cut point the WG demonstrated a statistically significant 5.9 (p < 0.0001) within group reduction and a 4.7 (p = 0.03) difference compared to the SG at completion of the 12 week intervention. While the magnitude of the reduction at 6 and 12 months also favoured the WG (7.1 v 3.1; and 8.3 v 3.4 respectively) the results were not statistically significant (p = 0.08 & p = 0.06).

We do not know if our community based recruitment strategy influenced CLBP participant motivation differently than if they were recruited via a clinical route, and may need to be considered when tailoring future walking interventions within a clinical population. However, the prevalence of CLBP in any given community is likely to be substantial, yet not all who report the condition will be seeking management for the disorder. There will likely be a number of reasons why treatment from a health professional is not being sought, including: self-management strategies, symptom tolerance, lack of previous treatment benefit, financial pressures, other accessibility barriers and a raft of other psychosocial factors [52‐55]. We did not record who was currently receiving clinical management from a health professional or identify those who were self-managing their condition, and thus cannot identify whether this was a factor in the recruitment and retention rates in the study or their outcomes. We also did not undertake a comparative evaluation of step count for the SG at 12 weeks and thus cannot determine whether a standardized package of care can also influence mean daily step count over this period of time. Thus there is the potential for a positive bias response for the WG and a negative bias for the SG. At the completion of the study the research physiotherapist commented on how several SG participants voiced disappointment at not being included in the WG intervention. While the outcome measures used in this study were considered extensive, providing a reasonable profile of psychosocial parameters, a number of other measures such as pain duration, depression, sleep deprivation, work participation, level of education, current use of medication and level of education were not gathered or included. We were also unable to gather sufficient data from our participants relative to the costs of managing their disorder at 12 week, 6 and 12 month time points and were unable to undertake a meaningful cost comparison for between group effects.

We consider the powered sample size (n = 174) a strength of the study with an acceptable number of drop outs. This has allowed analyses with mixed effect models for both observed and imputed (intention to treat) data as well as allowing post-hoc analyses in order to help identify potential scenarios where the intervention may have most utility or most effect. Although there is potential for a type II error in accepting the null hypothesis at 12 weeks, where 37 participants had withdrawn from the study, an intention to treat analysis also found no significant difference between both groups at this time point, or at 6, or 12 months. Our study design also used only one physiotherapist to deliver the intervention, thus eliminating between-therapist variations in program delivery impacting the outcomes of the study. While the results of this study indicate promising potential for a community based walking intervention future research with an adequately powered sample size, focusing on moderately disabled ODI inclusion criteria and low daily step count [45], will be required. Design of such a study will also need to consider strategies to optimize recruitment and retention. Future trials should also consider investigating for differences or non inferiority/equivalence in clinical outcomes between a community walking interventions for patients with CLBP compared with traditional face-face treatment. Our results indicate the potential for positive benefits of a community walking programme and, considering the mode of delivery; may provide a relatively simple and clinically effective way to manage patients with CLPB.