Sample size:
The sample size was calculated with reference to the effect size of 0.052 (partial eta
square) being worked out from the primary outcome of Roland Morris Disability Questionnaire
obtained from the pilot study. G*Power 3.1.9.4 was used to calculate the sample size. With
power of 0.95 and alpha value of 0.05, the total sample size is 68. With reference to the
attrition rate of approximately 20% in the pilot study, the sample size will become 43
subjects in each group and with total of 86 subjects will be recruited.Subjects will be
recruited from local community elderly community centers.
Randomization:
The subjects will be randomly assigned by the principal investigator to either intervention
group of GrExPACT or control group of GrEx using computerized randomization software.
Permuted blocked randomization with a block size of four and stratified by gender and STarT
Back category will be used as to ensure the groups are balanced. The allocation will be
concealed and stored in an encrypted file storing in a password protected computer.
Corresponding group therapy class will be arranged to the patient accordingly.
Study design:
86 subjects with chronic nonspecific LBP subject will first receive a 30-minute triage
screening by a physiotherapist for inclusion criteria, exclusion criteria and red flags as to
confirm the subjects are belonging to chronic nonspecific LBP and is suitable for the study.
The red flags include night pain, 24-hour pain, unexplained weight loss, night sweats, fever,
change in bowel and urinary habits and saddle anesthesia. Subjective examination for body
chart and physical examination include trunk range of motion, myotome, dermatome, reflexes,
palpation, and neuro-tension test will be performed when applicable.
Each subject will participate weekly group program for five consecutive weeks after the group
randomization. The size of the group is about 10. Each session for both intervention group
and control group will last for 105 min and will receive 60-minute group exercise therapy
includes supervised stretching, mobilization, stabilization and strengthening exercise for
the muscles around lumbar, hips and low limbs followed by functional and aerobic training.
The exercises are selected with reference to the National Institute for health and care
Excellence (NICE) guidelines, systematic review for physical activities for elderly with
chronic LBP and experience from the previous pilot trial which is safe and effective for
elderly with nonspecific chronic LBP. The exercise will be taught to patient progressively
from lying to sitting in first two sessions and adding more advance standing to functional
and aerobic training in subsequent sessions. The resistance of the TheraBand and step height
for functional training will tailor made and increase according to individual capability.
Each patient will be given an exercise pamphlet, goal setting worksheet and home exercise
record sheet. Patients are encouraged to utilize local community exercise facilitates and
bring back the home exercise record sheet each time for checking of compliance of practicing
home exercise.
Both groups of patients will have a physiotherapist leading discussion. For the GrEx group,
the discussion will last for 45 minutes. It involves discussion for back care and exercise
referencing to the back school that is a common educational and training program given to
patients with low back pain. The content includes anatomy of the spine, cause for pain,
self-management, correct manual lifting technique, ergonomic advice, and benefit of regular
exercise. For the GrExPACT group, the discussion will use the Acceptance and Commitment
Therapy (ACT) approach and will also last for 45 minutes. The content of the discussion will
follow the protocol-based ACT extracted from the protocol for the contextual pain management
by physiotherapy being used in INPUT center of St Thomas Hospital, London and physiotherapy
informed by acceptance and commitment therapy protocol (PACT) .
Qualification of the intervention provider:
The intervention providers are registered physiotherapist in Hong Kong who had more than 30
years of clinical experience in treating patient with musculoskeletal problem at public
physiotherapist outpatient clinic. For the background of ACT training, the physiotherapists
had received training for taught course for ACT and had participated in a two-day clinical
attachment for the contextual pain management program in INPUT Center at St. Thomas Hospital
in London of United Kingdom in 2018. Besides the participation in the local pilot trial for
GrExPACT study, they had also participated in the development for the local clinical service
team for stratified care and combined the physical and psychological approach in management
of high-risk back pain patients since 2015.
Data processing and statistical analysis:
The statistical analysis will be carried out using IBM SPSS version 28 software. The
demographically data will be presented by descriptive statistics. For continuous data, it
will be presented as mean, standard deviation and range. For categorical data, it will be
presented as frequency and percentage. Normality will be first screened by Boxplot, and
further assessed by the Shapiro-Wilk test. For the primary and secondary outcomes, two way
repeated measure ANOVA will be carried out. For the effect of time, the post hoc test will be
carried out for testing the differences of outcome scores for pre-intervention verse
immediate after the program; pre-intervention verse at 3 months; and immediate after the
program verse at 3 months. For the effect of intervention, post hoc tests at each time point
will be carried out when necessary. Significance was set at p < 0.05. Intention-to-treat
analysis will be used and missing data will be replaced with data from the nearest previous
non-missing data. Effect sizes (Partial eta squared) will also be computed to establish the
magnitude of the treatment effects. The effect sizes will interpreted as small (η2=0.01),
medium (η2=0.06) or large (η2=0.14).
Clinical significance:
In the management of elderly patient with chronic nonspecific low back pain (LBP), to face
the aging population, growing high patient volume and limited resources in health care, an
effective and efficient service model is urged. The service model of GrExPACT in the present
randomized control trial involve tailor made and resources saving strategy by using concept
of stratified care with STarT Back Screening Tool, physical therapy with group exercise and
psychological therapy with group ACT lead by physiotherapist. With the present study, the
effectiveness, synergistic effect, and adaptability to local culture for combining
physiotherapy group exercise with acceptance and commitment therapy delivered by
physiotherapist (GrExPACT) could be studied. The potential positive finding may enhance the
role of physiotherapist using the psychological approach in the management of chronic
nonspecific LBP and provide evidence support for the proposed more comprehensive, tailor made
and resources saving service model of GrExPACT. This may help to reform a more effective and
efficient model of care in Hong Kong.