Interferential Current Stimulation
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Interferential current stimulation (IFS) is a type of electrical stimulation. It is believed that IFS permeates the tissues more effectively and thus is more comfortable than transcutaneous electrical nerve stimulation (TENS). Interferential current stimulation has been investigated primarily as a technique to reduce pain but has also been proposed to increase function of patients with osteoarthritis and to treat other conditions such as dyspepsia, irritable bowel syndrome, and constipation.
Interferential current stimulation (IFS) is a type of electrical stimulation that uses paired electrodes of 2 independent circuits carrying high-frequency (4,000 Hz) and medium-frequency (150 Hz) alternating currents. The superficial electrodes are aligned on the skin around the affected area. It is believed that IFS permeates the tissues more effectively and, with less unwanted stimulation of cutaneous nerves, is more comfortable than transcutaneous electrical stimulation (TENS). Interferential stimulation has been investigated as a technique to reduce pain, improve range of motion, and treat a variety of gastrointestinal disorders. There are no standardized protocols for the use of interferential therapy; the therapy may vary according to the frequency of stimulation, the pulse duration, treatment time, and electrode-placement technique.
A number of interferential stimulator devices have received 510(k) marketing clearance from the U.S. Food and Drug Administration (FDA), including the Medstar™ 100 (MedNet Services) and the RS-4i® (RS Medical).
There are no specific CPT codes describing interferential current stimulation. The following CPT codes might be used:
64550: Application of surface (transcutaneous) neurostimulator
97014: Application of a modality to one or more areas; electrical stimulation (unattended)
The following HCPCS code might also be used:
G0283: Electrical stimulation (unattended), to one or more areas for indication(s) other than wound care, as part of a therapy plan of care.
Effective for 2012, the following HCPCS codes are available for these devices:
S8130 Interferential current stimulator, 2 channel
S8131 Interferential current stimulator, 4 channel
BlueCard/National Account Issues
State or federal mandates (e.g., FEP) may dictate that all devices approved by the U.S. Food and Drug Administration (FDA) may not be considered investigational, and thus these devices may be assessed only on the basis of their medical necessity.
This policy was originally created in 2003 and was updated regularly with searches of the MEDLINE database. The most recent literature search was performed for the period October 2011 through October 2012. In 2012, MEDLINE was searched for the period of the past 5 years for literature on interferential current stimulation (IFS) for treating conditions other than pain. Following is a summary of the key literature to date:
Musculoskeletal pain, range of motion, and function
In 2010, Fuentes and colleagues published a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating the effectiveness of IFS for treating musculoskeletal pain. (1) A total of 20 RCTs met the following inclusion criteria: included adults diagnosed with a painful musculoskeletal condition (e.g., knee, back, joint, shoulder or osteoarthritic pain); compared IFS alone or as a co-intervention to placebo, no treatment, or an alternative intervention; and assessed pain on a numeric scale. Fourteen of the trials reported data that could be included in a pooled analysis. Interferential current stimulation as a stand-alone intervention was not found to be more effective than placebo or an alternative intervention at reducing pain. For example, a pooled analysis of 2 studies comparing IFS alone and placebo did not find a statistically significant difference in pain intensity at discharge; the pooled mean difference (MD) was 1.17 (95% confidence interval [CI]: -1.70 to 4.05). In addition, a pooled analysis of 2 studies comparing IFS alone and an alternative intervention (e.g., traction or massage) did not find a significant difference in pain intensity at discharge; the pooled MD was -0.16, 95% CI: -0.62 to 0.31. Moreover, in a pooled analysis of 5 studies comparing IFS as a co-intervention to a placebo group, there was a non-significant finding (MD=1.60, 95% CI: -0.13 to 3.34). The meta-analysis found IFS plus another intervention to be superior to a control group (e.g., no-treatment). A pooled analysis of 3 studies found an MD of 2.45 (95% CI: 1.69 to 3.22). The latter analysis is limited in that the specific effects of IFS versus the co-intervention cannot be determined, and it does not control for potential placebo effects.
The 2 trials identified that compared IFS alone to placebo had relatively small sample sizes in each treatment group. A 2005 trial by Defrin and colleagues included a total of 62 patients with osteoarthritic knee pain. (2) Patients were randomly assigned to one of 6 groups (there were 4 active treatment groups and 2 control groups, sham and non-treated). Acute pre- versus post-treatment reductions in pain were found in all active groups but not in either control group. Stimulation resulted in a modest pre-treatment elevation of pain threshold over the 4 weeks of the study. In 1987, Taylor and colleagues randomly assigned 40 patients with temporomandibular joint syndrome or myofascial pain syndrome to undergo either active or placebo interferential therapy. (3) The principal outcomes were pain assessed by a questionnaire, as well as range of motion. There were no statistically significant differences in the outcomes between the 2 groups.
Representative recent trials on IFS for treating musculoskeletal pain are described below.
In 2012, Atamaz and colleagues conducted a double-blind RCT comparing the efficacy of IFS, transcutaneous electrical stimulation (TENS), and shortwave diathermy in 203 patients with knee osteoarthritis. (4) Patients were randomized to one of 6 groups, 3 with active treatment and 3 with sham treatment. The primary outcome was a 0 to 100 visual analog scale (VAS) assessing knee pain. Other outcomes included range of motion, time to walk 15 meters, paracetamol intake, the Nottingham Health Profile (NHP) and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). At the 1-, 3-, and 6-month follow-ups, there was not a statistically significant difference among the 6 groups in the VAS pain score, the WOMAC pain score or the NHP pain score. Moreover, the WOMAC function score, time to walk 15 meters, and the NHP physical mobility score did not differ significantly among groups at any of the follow-up assessments. At the 1-month follow-up, paracetamol intake was significantly lower in the IFS group than the TENS group.
In 2011, Facci and colleagues in Brazil published an RCT that compared IFS (n=50) and TENS (n=50) to a no-treatment control group (n=40) in patients with chronic low-back pain. (5) Patients were assessed by a blinded evaluator before and after completing ten 30-minute treatment sessions over 2 weeks. Patients in the control group were reassessed after 2 weeks. A total of 137 of 150 (91%) patients completed the intervention; analysis was intention to treat. The mean pain intensity, as measured by a 10-point VAS, decreased 4.48 cm in the IFS group, 3.91 cm in the TENS group, and 0.85 cm in the control group. There was not a statistically significant difference in pain reduction in the active treatment groups. Both groups experienced significantly greater pain reduction than the control group. Since a sham treatment was not used, a placebo effect cannot be ruled out when comparing active to control treatments. Moreover, findings from this trial do not demonstrate equivalence between IFS and TENS; studies with larger numbers of patients that are designed as equivalence or non-inferiority trials would be needed before drawing this conclusion.
In a 2011 study, Gundog and colleagues in Turkey randomly assigned 60 patients with knee osteoarthritis to 1 of 4 groups; 3 IFS groups at frequencies of 40 Hz, 100 Hz, and 180 Hz, or sham IFS. (6) IFS or sham IFS treatments were performed 5 times a week for 3 weeks. During the sham treatment, placement of the pads was the same and duration was the same, but no electrical stimulation was applied. The primary outcome was pain intensity assessed by the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). Mean WOMAC scores one month after treatment were 7.2 in the 40 Hz group, 6.7 in the 100 Hz group, 7.8 in the 180 Hz group, and 16.1 in the sham IFS group (p<0.05 compared to the active treatment groups) . Secondary outcomes also showed significantly higher benefit in the active treatment groups compared to the sham IFS group. For example, one outcome was pain on movement according to a 100-point VAS score. One month after treatment, the mean VAS score was 16.0 in the 40 Hz group, 17.0 in the 100 Hz group, 22.5 in the 180 Hz group, and 58.5 in the sham group. There were no significant differences in outcomes among the 3 active treatment groups. The number of patients assigned to each group and patient follow-up rates were not reported.
Conclusions: A large number of RCTs have been performed using IFS for musculoskeletal conditions. These have varied in the adjunct treatments that are used, comparison groups, types of controls, and outcome measures. Many of these trials have methodologic limitations such as an inadequate placebo control and/or the use of multiple treatment modalities. While some of these studies have reported benefit, the majority do not. A meta-analysis of RCTs did not find a significant benefit of IFS over control for treating pain. The body of evidence suggests, although is not definitive, that IFS is not efficacious for improving pain, function and/or range of motion for patients with musculoskeletal conditions.
Several RCTs evaluating IFS for treating children with constipation and/or other lower gastrointestinal symptoms were identified. The RCTs had small sample sizes and did not consistently find a benefit of interferential stimulation. For example, in 2012, Kajbafzadeh and colleagues in Iran randomized 30 children with intractable constipation to receive IFS or sham stimulation. (7) Children ranged in age from 3 to 12 years-old, and all had failed 6 months of conventional therapy e.g., dietary changes and laxatives. Patients received fifteen 20-minute sessions, 3 times a week over 5 weeks. Over 6 months, the mean frequency of defecation increased from 2.5 times per week to 4.7 times per week in the treatment group and from 2.8 times per week to 2.9 times per week in the control group. The mean pain during defecation score decreased from 0.35 to 0.20 in the treatment group and from 0.29 to 0.22 in the control group. The authors reported that there was a statistically significant difference between groups in constipation symptoms.
Another RCT was published by Clarke and colleagues in 2009; the study was conducted in Australia. (8) Thirty-three children with slow transit constipation (mean age, 12 years) were randomized to receive IFS or sham treatment. They received twelve 20-minute sessions over 4 weeks. The primary outcome was health-related quality of life and the main instrument used was the Pediatric Quality of Life Inventory (PedsQL). The authors only reported within-group changes; they did not compare the treatment and control groups. There was not a statistically significant change in QOL, as perceived by the parent in either the active or sham treatment group. The mean parentally perceived QOL scores changed from 70.3 to 70.1 in the active treatment group and from 69.8 to 70.2 in the control group. There was also no significant difference in QOL, as perceived by the child after sham treatment. The score on the PedQL group as perceived by the child, did increase significantly in the active treatment group (mean of 72.9 pre-treatment and 81.1 post-treatment, p=0.005).
Irritable bowel disease
An RCT with adults was published in 2012 by Coban and colleagues in Turkey. (9) The authors randomized 67 individuals with irritable bowel syndrome to active or placebo interferential current simulation (IFS). Patients with functional dyspepsia were excluded. Patients received a total of four 15-minute sessions over 4 weeks. Fifty-eight of 67 (87%) patients completed the study. One month after treatment, primary outcomes measures did not differ significantly between the treatment and control groups. Treatment response was defined as more than a 50% improvement in symptoms. For the symptom of abdominal discomfort, for example, the response rate was 68% in the treatment group and 44% in the control group. For bloating and discomfort, the response rate was 48% in the treatment group and 46% in the placebo group. Using a visual analogue scale (VAS) measure, 72% of the treatment group and 69% of the control group reported improvement in abdominal discomfort.
One RCT, by Koklu and colleagues in Turkey, was identified that evaluated interferential current stimulation for treating dyspepsia. (10) The study randomized patients to active IFS (n=25) or sham treatment (n=25); patients were unaware of treatment allocation. There were 12 treatment sessions over 4 weeks; each session lasted 15 minutes. A total of 44 of 50 (88%) randomized patients completed the therapy session and follow-up questionnaires at 2 and 4 weeks. The authors did not specify primary outcome variables; they measured the frequency of 10 gastrointestinal symptoms. In an intention-to-treat (ITT) analysis at 4 weeks, IFS was superior to placebo for the symptoms of early satiation and heartburn, but not for the other 8 symptoms. For example, before treatment, 16 of 25 (64%) patients in each group reported experiencing heartburn. At 4 weeks, 9 patients (36%) in the treatment group and 13 patients (52%) in the sham group reported heartburn; p=0.02. Among symptoms that did not differ at follow-up between groups, 24 of 25 patients (96%) in each group reported epigastric discomfort before treatment. In the ITT analysis at 4 weeks, 5 of 25 patients (20%) in the treatment group and 6 of 25 (24%) patients in the placebo group reported epigastric discomfort.
Conclusions: IFS has been tested for a variety of gastrointestinal (GI) conditions, with a small number of trials completed for each condition. The results of these trials are mixed, with some reporting benefit and others reporting no benefit. This body of evidence is inconclusive to determine whether IFS is an efficacious treatment for GI conditions.
There is insufficient evidence from well-designed trials that interferential current stimulation (IFS), a type of electrical stimulation, improves health outcomes (e.g., pain, range of motion) for patients diagnosed with painful musculoskeletal conditions. The limited amount of evidence from a few small trials comparing IFS alone to a placebo or sham intervention for treating does not consistently show benefit. Some trials do not control for potential placebo effects, others do not adequately evaluate the incremental effects of IFS beyond that of a co-intervention and/or do not adequately evaluate the equivalence of IFS and an alternative intervention. There is also insufficient evidence that IFS improves health outcomes for patients with other conditions, such as dyspepsia, irritable bowel syndrome, and constipation. Therefore, interferential stimulation is considered investigational.
Practice Guidelines and Position Statements
Clinical practice guidelines from the American College of Physicians and the American Pain Society, published in 2007, concluded that there was insufficient evidence to recommend interferential stimulation for the treatment of low back pain. (11)
In 2008, the American College of Occupational and Environmental Medicine (ACOEM) issued a guideline on management of chronic pain. The guideline concluded that the evidence on the effectiveness of interferential stimulation for the treatment of complex regional pain syndrome (CRPS) is insufficient and the intervention is not recommended. (12)
No clinical guidelines were identified that discussed interferential current stimulation for the treatment of dyspepsia, constipation, or irritable bowel disease.
Medicare National Coverage
No national coverage determination.
- Fuentes JP, Armijo Olivo S, Magee DJ et al. Effectiveness of interferential current therapy in the management of musculoskeletal pain: a systematic review and meta-analysis. Phys Ther 2010; 90(9):1219-38.
- Defrin R, Ariel E, Peretz C. Segmental noxious versus innocuous electrical stimulation for chronic pain relief and the effect of fading sensation during treatment. Pain 2005; 115(1-2):152-60.
- Taylor K, Newton RA, Personius WJ et al. Effects of interferential current stimulation for treatment of subjects with recurrent jaw pain. Phys Ther 1987; 67(3):346-50.
- Atamaz FC, Durmaz B, Baydar M et al. Comparison of the efficacy of transcutaneous electrical nerve stimulation, interferential currents, and shortwave diathermy in knee osteoarthritis: a double-blind, randomized, controlled, multicenter study. Arch Phys Med Rehabil 2012; 93(5):748-56.
- Facci LM, Nowotny JP, Tormem F et al. Effects of transcutaneous electrical nerve stimulation (TENS) and interferential currents (IFC) in patients with nonspecific chronic low back pain: randomized clinical trial. Sao Paulo Med J 2011; 129(4):206-16.
- Gundog M, Atamaz F, Kanyilmaz S et al. Interferential current therapy in patients with knee osteoarthritis. Am J Phys Med Rehabil 2012; 91(2):107-13.
- Kajbafzadeh AM, Sharifi-Rad L, Nejat F et al. Transcutaneous interferential electrical stimulation for management of neurogenic bowel dysfunction in children with myelomeningocele. Int J Colorectal Dis 2012; 27(4):453-8.
- Clarke MC, Chase JW, Gibb S et al. Improvement of quality of life in children with slow transit constipation after treatment with transcutaneous electrical stimulation. J Pediatr Surg 2009; 44(6):1268-72; discussion 72.
- Coban S, Akbal E, Koklu S et al. Clinical trial: transcutaneous interferential electrical stimulation in individuals with irritable bowel syndrome - a prospective double-blind randomized study. Digestion 2012; 86(2):86-93.
- Koklu S, Koklu G, Ozguclu E et al. Clinical trial: interferential electric stimulation in functional dyspepsia patients - a prospective randomized study. Aliment Pharmacol Ther 2010; 31(9):961-8.
- Chou R, Qaseem A, Snow V et al. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med 2007; 147(7):478-91.
- American College of Occupational and Environmental Medicine. Chronic pain. Available online at: www.guidelines.gov. Last accessed November, 2012.
|CPT||64550||Application of surface (transcutaneous) neurostimulator|
|97014||Application of a modality to 1 or more areas; electrical stimulation (unattended)|
|97032||Application of modality to one or more areas; electrical stimulation (manual), each 15 minutes (attended)|
|ICD-9-CM diagnosis||Investigational for all relevant diagnoses|
|HCPCS||G0283||Electrical stimulation (unattended), to 1 or more areas for indication(s) other than wound care, as part of a therapy plan of care|
|E1399||Durable medical equipment, miscellaneous|
|S8130||Interferential current stimulator, 2 channel|
|S8131||Interferential current stimulator, 4 channel|
|ICD-10-CM (effective 10/1/14)||Investigational for all relevant diagnoses|
|G56.40-G56.42||Causalgia of upper limb code range|
|G57.70-G57.72||Causalgia of lower limb code range|
|G89.0-G89.4||Pain, not elsewhere classified code range|
|G90.50-G90.59||Complex regional pain syndrome I code range|
|M25.50-M25.579||Pain in joint code range|
|M54.00-M54.9||Dorsalgia code range|
|M79.60-M79.676||Pain in limb, hand, foot, fingers and toes code range|
|ICD-10-PCS (effective 10/1/14)||ICD-10-PCS codes are only used for inpatient services. There is no specific ICD-10-PCS code for the initiation of this therapy.|
Electrical Stimulation, Interferential
|07/17/03||Add policy to Durable Medical Equipment section||New policy|
|11/9/04||Replace policy||Policy updated with literature review; policy statement unchanged|
|08/17/05||Replace policy||Policy updated with literature review; policy statement unchanged|
|12/14/05||Replace policy||Policy updated with literature review: policy statement unchanged.|
|12/12/06||Replace policy||Policy updated with literature review: policy statement unchanged.|
|04/09/08||Replace policy||Policy updated with literature review; references 7-9 added; policy statement unchanged|
|10/06/09||Replace policy||Policy updated with literature search, no references added, policy rationale edited extensively. The term, “for treatment of pain,” was added to the policy title and policy statement, intent of policy statement unchanged.|
|11/11/10||Replace policy||Policy updated with literature search; references 1 and 9 added; other references re-numbered or removed. Policy statement unchanged.|
|03/10/11||Replace policy – correction only||Corrected number of pooled mean difference in Fuentes and colleagues’ systematic review (from 1.17 to -1.17) in 2nd paragraph of Rationale section.|
|12/08/11||Replace policy||Policy updated with literature search; references 6 and 7 added; other references re-numbered or removed. Policy statement unchanged|
|12/13/12||Replace Policy||Policy updated with literature search. References 4, 7-10 added; other references renumbered or removed. “For treatment of pain” removed from policy statement. Title changed to “Interferential Current Stimulation.”|