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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effect of interferential therapy on pain with two different electrode placement
Scientific title
A double-blind placebo-controlled trial investigating the efficacy of interferential therapy using two different electrode placements on low back pain.
Secondary ID [1] 291419 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Low back pain 302433 0
Condition category
Condition code
Physical Medicine / Rehabilitation 302002 302002 0 0
Musculoskeletal 302227 302227 0 0
Other muscular and skeletal disorders

Study type
Description of intervention(s) / exposure
The intervention is a routine electrical stimulation modality called interferential therapy (IFT) used for the management of musculoskeletal pain in physiotherapy clinics. IFT is used via applying 4 rubber electrodes placed around the painful area and conducting two medium-frequency currents, around 4000Hz, to the painful area with the premise of producing a low-frequency effect deep inside the body with minimum skin irritation. IFT is adjusted to produce a strong but comfortable tingling sensation over 20 minutes which in turn is proposed to reduce subject's pain severity. In present work, two different electrode placement were compared, in relation to the painful spot. The first was the traditional placement of electrodes where the painful spot is located in the crossing pint of the two intersecting currents. The second was external placement where the painful spot was located at 2 centimeters outside the borders of the electrodes. Standardized placements of the painful spot were achieved by using a transparent sheet where the places of the IFT electrodes were determined via making 4 square holes in a quadrant shape. Additionally, two circular holes were made, one in the middle of the four square holes and one at 2 centimeters outside the borders of the squared holes. The IFT electrodes were placed in the squared holes then based on the tested application placement the circular whole was placed on the painful spot so the placement is guided either traditional or external application. A frequency current of 100Hz was used for admitting the IFT for all subject as this frequency is commonly used for pain management in physiotherapy clinics.Additionally, the current intensity was adjusted at the comfort at each subject in a way that strong but comfortable sensation is felt. Current intensity was increased or decreased based on individual sensation so that at all times current is felt as strong and comfortable. This procedure was carried out in a single session for 20 minutes only as this was the aim of the experiment.
Intervention code [1] 297452 0
Treatment: Devices
Intervention code [2] 297453 0
Comparator / control treatment
Control groups were exposed to the same procedure as with the intervention group (treatment with IFT) but the machine was off throughout the treatment session (20 minutes). Two control groups were recruited in this study, one for each electrode placement type.
Control group

Primary outcome [1] 301427 0
Subject reported pain severity on a 10-centimetre visual analogue scale (VAS). The scale has two ends; one represents no pain and the other represents the worst pain possible. Subject was asked to put a mark on the scale to show the severity of his/her pain . Then these marks were digitised using a 10 cm plastic ruler for analysis purposes.
Timepoint [1] 301427 0
VAS was measured two times, before treatment with IF and immediately after 20 minutes of OFT.
Primary outcome [2] 301428 0
Pressure pain threshold (PPT) was measured using a digital algometer (FDX 50; Wagner Instruments) with a 1cm2 rubber tip that was placed on the skin of most tender point. Pressure was recorded in kilopascal (kPa), with the algometer recording graduations of 1.96 kPa) and gradually increased with 98 kPa per second until the subject indicated that the pressure changed to pain by saying “pain”, after which the algometer was immediately removed from the skin and maximum pressure was copied from the algometer screen
Timepoint [2] 301428 0
PPT was measure two times, before treatment with IFT and immediately after 20 minutes of IFT.
Primary outcome [3] 301429 0
Pain distribution was measured from the most tender spot down to the distal point of pain the subject feels. A body diagram of 8.6 cm in length, from the head to the big toes, was used. Subject was asked to draw a line starting from the most tender spot and ends as far as his/her pain goes down. The line was measured using a ruler to represent pain distribution on the diagram and true pain distribution was calculated based on subjects hight..

Timepoint [3] 301429 0
Pain distribution was measured twice, one before treatment with IFT and one immediately after 20 minutes of IFT.
Secondary outcome [1] 332606 0
Range of motion (ROM) of the back, forward flexion was measured to determine Improvement in the back mobility with IFT. ROM was measured by asking subjects to make maximum forward bend of their trunk from standing while sliding their hands on the front side of their lower limbs. The examiner then recorded the distance from the tip of the middle finger to the ground in centimetres.
Timepoint [1] 332606 0
ROM was measured two times, before and immediately after the treatment session with IFT.

Key inclusion criteria
The inclusion criteria included that they are in age range of 18 to 70 years with body mass index 18 - 40 kg/m2, have low back pain with or without leg pain and haven’t been treated with IFT before or at least in the last two years.
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Subjects were excluded from the study if they have infection, neoplasms, metastasis, osteoporosis, rheumatoid arthritis, fractures, metabolic systemic disorder, heart disease, renal disease, intellectual disability and breaks or irritation of the skin of back.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Subjects removed one of identical pieces of paper from a dark envelope on which there was a number that refers to the group he is allocated to and give it to the therapist.
Before assigning the subject to the group and starting the treatment session, the assessor who had no knowledge as to which group the subject was assigned, assessed subjects pain and range of motion and left the treatment cubicle. Then, the therapist came into the cubicle and positioned the subject, applied the electrodes and operated the machine according to the assigned group. Immediately after 20 minutes of either true or placebo IFT, as per the group, the therapist left the cubicle and the assessor returned and assessed the pain and range of motion again.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
162 numbers written on identical pieces of paper were placed in a dark envelope. Each number refers to one of the tested groups. On an external index sheet these numbers were matched to their corresponding groups i.e. 1 refers to group 1, 2 refers to group 2, 3 refers to group 3, 4 refers to group 4, 5 refers to group 1, 6 refers to group 2 and so on. Subject was asked to remove one piece of paper from the envelope and give it to the therapist who assigned the subject to the group corresponding to the number (1 = tradition IFT application, 2 = external IFT application, 3 = placebo traditional IFT application, and 4 = placebo external IFT application).
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
Intervention assignment
Other design features
The people receiving the treatment did not know to which group they were assigned. The assessor did not know to which group the subject was assigned. The therapist who administered the treatment did not know about the outcomes of the assessment neither pre or post treatment.
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Based on a previous work using same intervention, 40 subjects in each group were estimated to be adequate for detecting a difference of at least 20% in maximum pain scores on the VAS between groups using a repeated measure design at a significance level of 0.05 and confidence level of 1-beta = 80%.

Data were entered into a computer using SPSS for windows version 20.0 (SPSS Inc., Chicago, IL). Results were cross-tabulated to examine the independence between variables. Statistical was performed using chi-square for the test of association and Fisher's exact test as appropriate. Where two or more continuous independent variables were examined, t-test and analysis of variance were used as adequate. An ANOVA with repeated measures was used to compare the means of the four groups where the multiple measures for the same participants were made per each group. Frequency tables' bar and lines graphs were performed as descriptive statistics. A P-value of less than 0.05 was considered significant in all statistical analysis.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 8728 0
Saudi Arabia
State/province [1] 8728 0
Eastern Province/ Dhahran

Funding & Sponsors
Funding source category [1] 295888 0
Name [1] 295888 0
Prince Sultan Military College of Health Science
Address [1] 295888 0
Biqiq Road, Dhahran, Saudi Arabia
Postcode: 31261
Country [1] 295888 0
Saudi Arabia
Primary sponsor type
Prince Sultan Military College of Health Science
Biqiq Road, Dhahran, Saudi Arabia
Postcode: 31261
Saudi Arabia
Secondary sponsor category [1] 294757 0
Name [1] 294757 0
Address [1] 294757 0
Country [1] 294757 0

Ethics approval
Ethics application status
Ethics committee name [1] 297167 0
Research Committee of Prince Sultan Military College of Health Sciences
Ethics committee address [1] 297167 0
Prince Sultan Military College of Health Sciences, Dhahran, Saudi Arabia
Postcode: 31261
Ethics committee country [1] 297167 0
Saudi Arabia
Date submitted for ethics approval [1] 297167 0
Approval date [1] 297167 0
Ethics approval number [1] 297167 0

Brief summary
Interferential therapy (IFT) is regularly used to manage musculoskeletal pain. The use of IFT is based on minimising skin impedance and producing maximum stimulation at the point of intersection of the two alternating currents, deep in tissue. Traditionally, IFT has been applied in a quadripolar way so that the two currents intersect in the painful area despite the highest voltage of IFT is being induced outside the intersection area of the two used currents. Clinically, no clear reduction effect of pain has been confirmed with this application method of IFT. It is probably true that placing the painful area outside the intersection spot of the two currents would reveal a significant pain reduction.
To investigate the pain reduction effect while placing the pain spot outside the crossing point of the two currents compared to the traditional method of applying IFT.
162 subjects with subacute low back pain were randomly assigned to one
4 groups which were: 1- external IFT application (where the most tender pain spot was located between the two electrodes at 2 cm outside of the external borders of the electrodes) 2- placebo external IFT application 3- traditional IFT application (where the most tender pain point was placed at the crossing area of the two currents of IFT) 
4- placebo traditional IFT application. Subjects were assessed for their pain before and after IFT session using visual analogue scale (VAS), pressure pain threshold (PPT), pain distribution and ROM. Groups 1 and 3 received 20 min of IFT at 100 Hz and comfortable stimulation intensity. Groups 2 and 4 received sham IFT for 20 min.
Results: VAS and ROM improved with all groups,P= 0.04 respectively. No statistical differences appeared between groups, for VAS P= 0.15 - 0.95 and for ROM P= 0.10 - 0.83. Active applications improved VAS and ROM to same extent, for VAS; external mean difference 5.36 (0.38) and traditional mean difference 5.33 (0.39), and for ROM; external mean difference 17.57 (2.12) and traditional mean difference 17.77 (2.27).There was a trend of better VAS reduction with active IFTs compared to placebos. Oppositely, PPT and pain distribution did not significantly change with any of the groups,P=0.48 respectively. No statistical difference between groups for PPT; P= 0.10 - 0.83, but between placebo groups for pain distribution (P=0.04). Both active applications changed PPT and pain distribution closely, for PPT; external mean difference 539.48 and traditional mean difference 551.99 (42.57)and for pain distribution; external mean difference 13.66 (3.67) and traditional mean difference 16.22 (3.74)
No therapeutic difference between external and traditional applications
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 73210 0
Dr Abulkhair Beatti
Address 73210 0
Armed Forces Centre for Health Rehabilitation,
Jaish Street, Taif, Saudi Arabia
Postcode: 21431
Country 73210 0
Saudi Arabia
Phone 73210 0
Fax 73210 0
Email 73210 0
Contact person for public queries
Name 73211 0
Dr Abulkhair Beatti
Address 73211 0
Armed Forces Centre for Health Rehabilitation,
Jaish Street, Taif, Saudi Arabia
Postcode: 21431
Country 73211 0
Saudi Arabia
Phone 73211 0
Fax 73211 0
Email 73211 0
Contact person for scientific queries
Name 73212 0
Dr Abulkhair Beatti
Address 73212 0
Armed Forces Centre for Health Rehabilitation,
Jaish Street, Taif, Saudi Arabia
Postcode: 21431
Country 73212 0
Saudi Arabia
Phone 73212 0
Fax 73212 0
Email 73212 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary