Background:
Continuous or intermittent lateral hip pain, also known as greater trochanteric pain
syndrome (GTPS), is a common chronic and disabling musculoskeletal condition. It usually
occurs during the fourth to sixth decades of life, predominantly among women. The
prevalence and incidence rates have been reported to be 4.2 and 3.3 per 1000
person-years, respectively, in the general practice population. The impact of GTPS is
reported to be debilitation, as it typically disturbs sleep and limits daily function and
participation in work.
Exercise and education are considered the cornerstone of treatment, and in recent
randomized controlled trials this combination has demonstrated significant improvements
in pain and function. However, studies have failed to show any difference between
specific hip exercises and non-specific (sham) exercises in combination with patient
education. As GTPS is recurrent and persistent of nature, person-centered care and the
incorporation of self-management strategies could be beneficial. To the investigators
knowledge, this study will be the first one to investigate self-management for the
current patient population. Results from the study may change the type, delivery, and
content of treatment for patients with GTPS, relevant for both primary- and secondary
care.
The main objective of the study is to evaluate the clinical effectiveness of a
self-management program compared to usual care for patients with GTPS.
Methods and analyses:
110 patients will be recruited and randomly allocated into one of two groups: 1)
self-management or 2) usual care. The randomization sequence will be computer-generated
with blocks of various size, unknown to any of the research team. Due to the nature of
therapeutic studies, blinding of the participants and the treating physiotherapist is not
possible. The investigator assessing the outcome measures will be blinded to group
allocation.
Descriptive statistics will be collected at baseline, and presented as means with
standard deviation (SD) or as medians with inter quartile range (IQR). The primary
analysis will be conducted on the intention to treat population and compare the two
intervention groups (self-management vs usual care) on mean difference in pain and
disability (VISA-G-N score) at baseline, 3 and 6 months. The estimated mean difference
between groups at 6 months (main endpoint) will be analyzed using a longitudinal mixed
effects model analysis of covariance. Baseline score on VISA-G-N, time, intervention and
interaction between time and intervention will be included as covariates. Secondary
outcomes assessed at multiple time points (baseline, 3, 6 and 12 months) will be analyzed
by the same approach as described for the primary outcome, on both the intention to treat
population and the per protocol population.
The degree of missingness will be explored using sensitivity analysis with multiple
imputation and/or the use of an alternative repeated measures mixed model analysis
accordingly, to assess the robustness of data. In addition, multivariable logistic and
linear regression analysis will be used to explore predictive factors, such as
demographics, expectations, clinical findings, and psychosocial factors for primary and
secondary outcomes. Model building will be done in a way that is appropriate for the
given sample sizes, by restricting the number of potential predictive factors and
considering shrinkage methods to stabilize predictions. Mediation analysis will be
performed to explore the causal pathway between treatment allocation and the primary
outcome of pain and disability by considering, amongst others, pain self-efficacy and
emotional distress as potential mediators that may be part of the causal pathway between
intervention and outcome.