Study design and ethical approval
This is a controlled, randomized, two-arm, double-blind study comparing: (i) patients with chronic low back pain treated with electrical dry needling, (ii) patients with chronic low back pain treated with conventional physiotherapy consisting of ischaemic compression, analytical stretching and a dossier of home lumbar spine exercises. Study participants will be randomly assigned to two groups (electrical dry needling group or conventional physiotherapy group) with a 1: 1 ratio.
This protocol has been drawn up following the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) (Appendix 3). The study will be carried out in partnership with the physiotherapy department of the University of Almería. Ethical approval for this trial was granted by University of Almería Research Ethics Committee (UALBIO2020/044). The study protocol was registered in an international clinical trial registry, Clinicaltrials.gov (protocol number NCT04804228).
A total of 80 patients aged between 30 and 65 years, diagnosed with non-specific chronic low back pain lasting more than 3 months who are not currently undergoing any type of treatment will be recruited. Patients will be randomised to two treatment groups (electrical dry needling or conventional physiotherapy). Participants will receive treatment once a week for three weeks in the physiotherapy laboratories of the University of Almería, with a follow-up evaluation at three weeks and two months after the start of treatment. During their first visit, participants will be screened for study eligibility according to the study inclusion and exclusion criteria, and will be assessed by a therapist blinded to the interventions. After this face-to-face evaluation, patients will be randomly assigned to one of the two groups and will receive the corresponding treatment for low back pain administered two researchers trained in the techniques used. All participants will sign the informed consent form, which complies with the Declaration of Helsinki of the World Health Organization (schedule of enrolment, interventions and assessments is shown in Figure 1).
Both male and female patients aged between 30 and 65 years with chronic low back pain lasting 3 months or more, with a low back pain disability score ≥ 4 on the Roland-Morris disability questionnaire (RMQ), and not receiving any other physiotherapy treatment are eligible for inclusion.
Patients with sensory and/or coagulation disorders, a history of spinal surgery, heart complications, concurrent severe central or peripheral nervous system disease, epilepsy, needle phobia, serious pathologies that can be the main cause of chronic low back pain (for example, presence of lumbar stenosis, spondylolisthesis, tumours, etc.), or patients contraindicated for transcutaneous electrical stimulation (TENS) will be excluded.
Randomization and blinding
Subjects will be randomised to two groups using a computer-generated (Epidat 4.2) table of random numbers generated . After randomization, participants will be assigned to either the experimental electrical dry needling group or the conventional physiotherapy control group in a ratio of 1:1. Randomization will be performed by the principal investigator.
There will be 40 participants in each group. The randomly generated group allocations will be placed in sealed opaque envelopes before being delivered to the participants and stored in locked cabinets.
The outcome assessor and study statistician will be blinded to the entire process. The outcome assessor will make no attempt to guess the participant's treatment group. The computer-generated outcome measures transmitted to the statistician will not contain any information that identifies the patient’s group.
After the initial evaluation, 80 patients with CLBP will be randomly assigned to one of the two groups and will receive electrical dry needling (experimental group) or conventional physiotherapy (control group). All participants will receive 1 session per week for 3 weeks, until they have received a total of 3 sessions. Patients must complete 100% of their scheduled face-to-face treatment sessions, and those in the control group must also complete 80% of the home exercise sessions in order to remain in the intention-to-treat analysis.
During the study, participants can only receive their assigned treatment; they cannot combine the study treatment with medications or any other treatment. Any interference in the treatment will be grounds for exclusion. Patients may abandon the study at any time, and the assigned interventions may be suspended or modified in a particular trial patient in response to improvement or deterioration (adverse effects) of low back pain. Adverse events will be reported to the principal investigator, who will monitor the affected patients and the possible causes of these events.
Electrical dry needling group
Patients assigned to the electrical dry needling group (n = 40) will receive up to three 30-minute treatment sessions (1 session per week for 3 weeks). Electrical stimulation will be applied bilaterally to the active and latent myofascial trigger points of the following muscles, following the MTrPs maps described by Travell and Simons:2,14 quadratus lumborum, multifidus and iliocostalis. The number of needle insertion sites will vary in each patient; the treating therapist will determine the points to be treated in each session based on whether they are active, latent or absent. Prior to needle insertion, the site will be sterilized with 70% alcohol using a cotton swab (Figures 3).
Two sizes of sterilized disposable stainless steel acupuncture needles will be used: 0.25 mm x 30 mm or 0.30mm x 40 mm. The size of the needle will depend on the patient’s physical constitution (i.e. muscle and/or connective tissue thickness). The needle will be inserted until it reaches the active or latent MTrP or taut band that causes the local twitch response.41 The needles will then be connected to an electric current and left in situ for 30 minutes (TensMed S82-Enraf Nonius).42,43 A low frequency current (2 Hz) will be generated by a TENS device with a moderate pulse duration (250 microseconds) and a continuous biphasic waveform at an intensity described by the patient as "mild to moderate".44
Conventional physiotherapy group
Patients assigned to the conventional physiotherapy group (n = 40) will receive ischaemic compression and analytical stretching of the quadratus lumborum, multifidus and iliocostal muscles once a week for a total of 3 weeks.
Ischaemic compression will consist of constant pressure stimulation with the thumb on each MTrP for between 30s and 2 min. This compression sequence will be repeated several times. The intensity of the pressure will be adjusted to a level at which each subject reports "comfortable pain", in order words, between the pain threshold and the maximum tolerable pain.46,47 See appendix 1 for the analytical stretching procedure.
These patients will also be given a dossier of home lumbar spine exercises to be performed 5 days a week for a total of 3 weeks (Appendix 2. Dossier of home exercises). To monitor compliance, patients will be instructed to note down in a booklet the dates on which they complete the exercises in the dossier.
At the beginning of the study, the following demographic data will be collected: age, sex, weight, height, education, and clinical presentation. Primary and secondary outcome measures will be evaluated at baseline prior to randomisation to different groups. This will be followed by an immediate post-treatment assessment (one day after the final intervention), and an evaluation two months after the end of the intervention (short-term follow-up).
Primary Outcome Measures:
- Roland Morris Disability Questionnaire (RMDQ). This self-reported questionnaire consists of 24 items that rate limitations in different activities of daily life attributed to low back pain, such as walking, bending over, sitting, lying down, dressing, sleeping, personal care and daily activities. Disability is rated from 0 points (best) to 24 points (worst).48
- Oswestry Disability Index (ODI). The Oswestry Disability Index assesses limitations in activities of daily living in 10 dimensions, each rated on a 6-point scale (0-5 points). The higher the score, the greater the disability. The overall score is expressed as a percentage and is used to classify people as minimally disabled (0%-10%), moderately disabled (20%-40%), severely disabled (40%-60%), crippling back pain (60%-80%), or bedridden (80%-100%).49
- Visual Analogue Scale (VAS). Study subjects will indicate the intensity of their pain on a 100 mm VAS. They are asked to situate their pain on a 100 mm horizontal line, where 0 mm indicates "no pain" and 100 mm indicates "the worst pain imaginable".50
Secondary outcome measures:
- Quality of life using the SF-36 questionnaire. The SF-36 is a short-form, multipurpose health survey with only 36 questions. The instrument contains eight subscales (physical function, physical role, body pain, general health, vitality, social function, emotional role, and mental health) and two summary scores: physical and mental health. Scores range from 0% to 100% and indicate self-perceived health-related quality of life.51,52
- Tampa Scale for kinesiophobia (TSK). This is a 17-item questionnaire that measures fear of movement and (re) injury. Patients rate their beliefs about their kinesiophobia on a 4-point scale ranging from strongly disagree to strongly agree.53,54
- Pittsburgh Sleep Quality Index (PSQI). This is a 10-item questionnaire with a total of 19 questions related to sleep habits in the previous month. The questions are divided into 7 areas, each with a score of between 0 and 3 points. The overall score ranges from 0 (no difficulty sleeping) to 21 points (severe difficulty sleeping).55
- Hospital Anxiety and Depression Scale (HADS). This scale consists of 14 items related to emotional distress (anxiety, depression) in populations suffering from a physical illness. It consists of two subscales (HADA: anxiety and HADD: depression) with seven items each that score from 0 (normal) to 3 (abnormal).56.57
- McQuade test. This test evaluates the isometric resistance of the flexor muscles of the trunk. The patient is placed supine and asked to flex the head and shoulders until the scapula is lifted off the table. The number of seconds they hold that position is recorded.58
- Anterior Trunk Flexion. Standing, with legs straight, the patient is asked to bend forward and attempt to touch the ground. They are told to stop when pain or limitation of movement appear. The distance, in cm, between the fingers and the ground is measured.59
- Spinal Mouse®. This is a safe, practical and easy-to-use instrument to measure the curvature of the spine in the frontal and sagittal planes and to assess the segmental mobility of the lumbar region.60
- Pressure Algometry (Wagner FPI 10 Algometer) in MTrPs. The algometer consists of a rubber tip and a dial that measures the pressure applied to the MTrP in increments of 0.5 kg. The pressure pain threshold will be assessed following the illustrations published by Travell and Simons.14
The sample size was calculated according to the specifications established by Willian.61 The calculations were based on the detection of differences of 2.5 points in the RMDQ (minimum detectable difference between means for a variance of 10 points in patients with chronic low back pain), assuming a standard deviation of 2.5 points, a 2-tailed test, an alpha (α) of 0.05 and a target power (beta) of 85%. The estimated target sample size has been calculated at 40 subjects per group.
The following specifications will be considered: α = 0.05, statistical power of 85% and loss to follow-up of 10%. The sample size calculation yielded a total of 92 participants to be randomized to two intervention groups.
Statistical analysis will be performed using SPSS© version 21.0 and STATA 14 using the principles of intention to treat. Comparisons will be made between the two study arms. We will calculate the difference between groups after the final treatment session and at two month post-intervention (short-term results).
The efficacy variable for this clinical trial is the difference between continuous variables (i.e., RMDQ, ODI, VAS, TSK, SF-36, PSQI, HADS, pressure algometry, McQuade test, and trunk range of movement) at baseline and at predetermined time points (electric dry needling treatment vs conventional physiotherapy):
The Kolmogorov-Smirnov test will be used to assess the normality of continuous variables.
The equality of means of the intragroup hypotheses will be analysed using the Student's t test for paired clinical variables in the case of parametric distributions and the Kruskal-Wallis H test in the case of non-parametric distributions.
One-way analysis of variance (ANOVA) will be used to test the intragroup hypothesis in the case of parametric distributions, and the Kruskal-Wallis H test will be used in nonparametric distributions.
Post hoc analysis will be obtained for parametric distributions, and Mann-Whitney U for nonparametric distributions.
The confidence interval will be set at 95% and the level of significance at 0.05.
No potential risks have been described so far, given that these can be prevented by the operator’s knowledge of anatomy, training and experience.62 Researchers will notify study subjects of possible adverse events in the informed consent and record any adverse events that occur over the course of the study . If such events are observed, the frequency of occurrence will be analysed between groups, and if patients have any questions or require additional information about any symptoms, they will be able to contact the principal investigator by phone or email.
Ethics and dissemination.
All participants will receive verbal and written information about the study before giving their consent to participate. They will be informed that they can leave the study at any time. Participants who agree to take part in the study will sign two copies of the informed consent form, one for the research and evaluation team and one for the participant.
All hard copies will be confidential and stored in a locked filing cabinet in the research group office and in electronic format in a password-protected database. The research team will monitor the integrity of the trial data. All participants, group assignments, treatment records sociodemographic data will be coded, and the results of the questionnaires will be scored.
The data collected on each participant will be kept under lock and key by the evaluator. If the data are in digital format, they will be stored in a computer with a secret access code known only to the evaluator.
The eligibility criteria, results, and analyses will not be modified once the first participant has been enrolled in the study. Any amendment to the protocol, including changes in the eligibility criteria, the results or the analyses, will be communicated to the Institutional Research Committee of the University of Almería and reported in articles and presentations disseminating the results of the trial.
The feasibility results will be published in peer-reviewed journals and presented at academic, clinical, and health services conferences.