Subacromial pain syndrome (SPS) is one of the most common causes of shoulder pain, leading to significant disability and socioeconomic burden. Although percutaneous electrical nerve stimulation (PENS) targeting the suprascapular nerve (SN) has shown positive therapeutic outcomes, individual response to the intervention varies considerably. This study aims to develop a multivariable predictive model to estimate clinical response to SN-targeted PENS in patients with SPS. The model will be built using clinical, psychological, and neural mechanosensitivity variables. The goal is to enhance patient selection and guide personalized treatment strategies.
Subacromial pain syndrome (SPS) includes a group of clinical entities related to rotator cuff tendinopathy and subacromial structures that cause shoulder pain and functional limitations. PENS applied to the suprascapular nerve (SN) has demonstrated effectiveness in reducing pain and improving short-term function in patients with SPS. However, variability in clinical response suggests the influence of individual characteristics that are not yet well understood. This study will conduct a prospective, single-arm, uncontrolled clinical trial involving 269 patients diagnosed with SPS. All participants will undergo a single ultrasound-guided session of PENS on the SN. The primary outcome will be post-treatment pain intensity measured with the Visual Analogue Scale (VAS). n addition to the primary outcome, several baseline variables will be collected to develop a multivariable beta regression predictive model. These variables include demographic data (age, sex, weight, height, BMI), clinical characteristics (pain duration in weeks, baseline pain intensity measured with the Visual Analogue Scale), psychological measures (Hospital Anxiety and Depression Scale - HADS), physical activity levels (International Physical Activity Questionnaire - Short Form), and measures of neural mechanosensitivity (pressure pain threshold on the infraspinatus and result of the suprascapular neurodynamic test). These predictors will be incorporated into the model regardless of their univariate significance, in line with best practices in predictive modelling. A beta regression model will be developed to predict post-treatment pain intensity. Internal validation and model stability will be assessed using bootstrap resampling methods. This protocol follows the TRIPOD guidelines for clinical prediction model development. Identifying reliable predictors of response will support clinical decision-making, helping to personalize physiotherapy approaches and improve the cost-effectiveness of SPS management. The findings may provide a robust foundation for future research and eventual clinical implementation of prediction tools for individualized therapy planning.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
269
Ultrasound-guided percutaneous electrical nerve stimulation applied to the suprascapular nerve using a monophasic or biphasic current at 10 Hz frequency and 250 μs pulse width. Intensity is progressively increased to patient tolerance, aiming to induce visible muscle contractions of the supraspinatus and infraspinatus. Duration of the session is 30 minutes.
Pain intensity
Pain intensity will be measured with a 100 mm Visual Analogue Scale (VAS), ranging from 0 mm (no pain) to 100 mm (worst imaginable pain). This is the primary outcome used to evaluate the clinical response to a single ultrasound-guided session of percutaneous electrical nerve stimulation (PENS) targeting the suprascapular nerve in patients with subacromial pain syndrome. This outcome will be used as the dependent variable in the multivariable predictive model.
Time frame: 4 weeks post-intervention
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