Interferential and horizontal therapies in chronic low back pain: a randomized, double blind, clinical study
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Interferential and horizontal therapies in chronic low back
pain: a randomized, double blind, clinical study
A. Zambito, D. Bianchini, D. Gatti, O. Viapiana, M. Rossini, S. Adami
Rheumatologic Rehabilitation, University of Verona, Italy.
Abstract
Objectives
Chronic Low Back Pain (CLBP) is one of the most frequent medical problems. Electrical nerve stimulation is
frequently used but its efficacy remains controversial.
Methods
Twenty-six men and 94 women with CLBP associated with either degenerative disk disease or previous multiple
vertebral osteoporotic fractures were randomly assigned to either interferential currents (IFT), horizontal therapy
(HT) or sham HT administered for 10, 40 and 40 minutes, respectively, daily for 5 days per week for two weeks
together with a standard flexion-extension stretching exercise program, Blind efficacy assessment were obtained at
baseline and at week 2, 6 and 14 and included a functional questionnaire (Backill), the standard visual analog
scale (VAS) and the mean analgesic consumption.
Results
At week 2 a significant and similar improvement in both the VAS and Backill score was observed in all three
groups. The Backill score continued to improve only in the two active groups with changes significantly greater
than those observed in control patients at week 14. The pain VAS score returned to baseline values at week 6 and
14 in the control group while in the IFT and HT groups it continued to improve (p< 0.01 vs controls). The use of
analgesic medications significantly improved at week 14 versus pretreatment assessment and over control patients
only in the HT group.
Conclusions
This randomized double-blind controlled study provides the first evidence that IFT and HT therapy are significantly
effective in alleviating both pain and disability in patients with CLBP. The placebo effect is remarkable at the
beginning of the treatment but it tends to vanish within a couple of weeks.
Key words
Chronic low back pain, multiple vertebral fractures, electrical nerve stimulation, interferential currents, horizontal
therapy, double-blind placebo controlled trial.
Clinical and Experimental Rheumatology 2006; 24: 534-539.Electric therapies and chronic low back pain / A. Zambito et al.
Antonino Zambito, Donatella Bianchini, Introduction standard deviation [SD] 71 ± 8 years;
Davide Gatti, Ombretta Viapiana, Chronic low back pain (CLBP) is one range 50 - 86 years) (Table I). The pa-
Maurizio Rossini, Silvano Adami of the most common medical problems tients were recruited from 371 consec-
Please address correspondence and in developed countries (1-3). Analgesic utive patients referred to our out-
reprint requests to: Prof. Silvano Adami, therapies may provide temporary pain patient clinic for CLBP associated with
Rheumatologic Unit, University of Verona
relief but the overall results remain degenerative disk disease without any
Ospedale, 37054 Valeggio s/Mincio,
Verona, Italy. largely unsatisfactory and their contin- component of radicular pain or estab-
E-mail: silvano.adami@univr.it uous use is often associated with seri- lished osteoporosis or other identifiable
Received on January 11, 2006; accepted in ous side effects (4). Nonpharmacologic disease. One hundred and forty-two did
revised form on April 11, 2006. alternatives include electrical nerve not meet the study criteria and 109 did
© Copyright CLINICAL AND EXPERIMEN- stimulation, (transcutaneous electrical not agree to participate in the study
TAL RHEUMATOLOGY 2006. nerve stimulation (5, 6), interferential most often due to their inability to
therapy (IFT) (7, 8) or percutaneous attend the out-patient treatment ses-
electrical nerve stimulation (9, 10), sions. The inclusion criteria were an
acupuncture (11, 12), spine manipula- age older than 50 years and a history of
tion (13) and exercise therapy (13, 14). CLBP, which had been stable for the
The efficacy of all these alternative previous 3 months, due to either severe
therapies remains controversial be- radiographic evidence of degenerative
cause most of the published studies lumbar disk disease or multiple (more
lack appropriate control groups or than one) compression fracture of the
blinding, or failed to include relevant last thoracic or of the lumbar spine
comparators. In the few studies with (T10 to L4) detected radiologically
acceptable methodological quality (9, within the previous 6 months. Exclu-
10), Fifteen – seventeen patients were sion criteria were any illness involving
assigned to each study group, a number major organ systems, history of alcohol
that is inadequate for any sub-analysis abuse, use of opioid containing med-
on the co-factors influencing the study ication, presence of radicular pain,
outcomes. It is claimed that IFT has an inability to complete the question-
advantage over other electrical currents naires, the use of a cardiac pacemaker,
in that its carrier frequency is associat- and previous experience with any type
ed with relatively lower skin resistance of electric therapy.
while still producing low frequency Patients with any professional commit-
effects within the tissues (15, 16). ment were also excluded. In all patients
Despite the widespread use of IFT in a lateral spine X-ray was obtained
clinical practice (15), the findings of immediately before treatment random-
controlled clinical trials are still incon- ization in order to exclude new or
clusive (18-20, 21 ). worsening vertebral fractures that had
Horizontal therapy (HT) (22) is a novel occurred less than 6 months previously.
analgesic therapy that is expected to The study protocol was approved by
extend the advantages of the traditional the local ethical committee (E.C., Asl
IFT. In order to evaluate its efficacy we 22, Bussolengo Verona, Italy) and
decided to test HT therapy in two informed consent was obtained from
“models” of back pain: patients with all patients prior to any enrolment pro-
CLBP associated with degenerative cedures.
disk disease or due to previous multiple The recruited patients were first strati-
vertebral osteoporotic fractures where fied according to the etiology of CLBP
chronic back pain is mostly related to (degenerative disk or vertebral frac-
misalignment of the spine with muscle tures) and then assigned to either HT,
contractions. To our knowledge, this is IFT or sham HT. Fifteen computer-gen-
the first double-blind, placebo-control- erated randomization blocks of 3:3:2
led, randomized study on nonpharma- for HT, IFT and sham HT, respectively,
cologic treatment of CLBP by IFT and were used for treatment assignment.
the first report on HT. Starting on the same day as randomiza-
tion, all patients began a standard flex-
Methods ionextension stretching exercise pro-
The study population comprises 26 gram (23) over 45 minutes, 5 times a
men and 94 women (mean age ± week for 2 weeks.
535Electric therapies and chronic low back pain / A. Zambito et al.
Treatment modalities patients familiar with electric therapies All patients with prevalent vertebral
The IFT therapy consisted of the place- and with what is sensed. fractures had been on treatment with
ment of 4 medium-sized (8X6 cm) Power analyses (25) were conducted to bisphosphonates for more than 12
cutaneous electrodal pads ( Phyaction determine the sample size needed to months. The study population was
787, Uniphy, Einhoven, NL) in a stan- demonstrate a difference of 1 in VAS made up exclusively of retired people.
dard dermatomal pattern, which were and of 5 in Backill score (in either The pretreatment evaluation for both
stimulated for 10 minutes at a modul- direction) assuming a standard devia- the Backill score and the pain VAS
ated frequency of 200 Hz. HT therapy tion of 1.7 and 6.5 respectively. We cal- score (Table I.) indicates that the qua-
consisted of the placement of 3 cutan- culated that 35 patients would be need- lity of life of this population was
eous electrodal pads (8 x 13 cm), one in ed in each treatment arm with a power severely deteriorated.
the lumbar zone and two others in the of 80% and an alpha of 0.05. All patients attended the full therapeutic
posterior proximal site of the thighs, program even though the adherence to
with a stimulation frequency oscillat- Data analysis the physical exercise program in terms
ing at 100 Hz between 4400 and 12300 The SPSS statistical software program of strength and duration of the exercises
Hz for the first 20 minutes and at the (version 11.0) was used for all statisti- was so variable from patient to patient
fixed frequency of 4400 Hz. for a fur- cal analyses. The changes in the VAS and even from day to day that a proper
ther 20 minutes (PRO ElecDT 2000, and Backill scores over time (pairwise assessment could not be carried out. Fig-
Hako med; D). data and between groups) were ana- ure 1 shows the percentage changes in
The sham HT treatment consisted of lyzed with repeated measures analysis pain and functional outcomes. At week
the placement of the same pads for the of variance and t-test, with a Bonfer- 2, immediately after the completion of
same time but no electrical stimulation roni comparison test applied for multi- the treatment program, a significant and
was applied to the probes. All treat- ple comparisons. Analysis of the cate- similar improvement in both the VAS
ments were administered for 5 days per gorical data on analgesic consumption and Backill score was observed in all
week for two weeks. for the three treatment modalities was three groups. The Backill score contin-
performed using χ2 test and Odds ratio ued to improve in all groups over base-
Assessment procedures where the changes in analgesic con- line assessment, possibly in relationship
Before initiating treatments, at the end sumption were categorized as im- with the exercise program. However, the
of the 2 weeks of therapy and then after proved or unchanged or worsened. All changes observed in the HT group were
4 (week 6) and 12 weeks (week 14), the analyses were repeated after adjusting significantly greater than those observed
patients were asked to complete the the values for age, gender and number in the sham HT group control patients at
Backill questionnaire (24), an exten- of prevalent vertebral fractures by week 14 (p < 0.05).
sion of the McGill Pain Questionnaire, covariance analysis. An intention-to- In the sham HT group, after the initial
including 27 functional questions and 4 treat analysis was preplanned but not improvement the VAS score slowly
questions qualifying the type of pain. A applied since all patients completed the worsened and it was not significantly
standard 10 cm visual analog scale 3 month follow-up. different from baseline at week 14. In
(VAS) was used to assess back pain, the IFT and HT groups the VAS score
with a score of zero equaling no pain Results continued to improve with changes
and 10 equaling worst bearable pain. The main clinical characteristics of the significantly different from those ob-
Patients were instructed not to change study population are listed in Table I. served in control patients.
the type of non-opioid analgesic med-
ications used during the course of the
study, which were represented by Table I. Clinical characteristics of study population.
nimesulide (63% ), paracetamol (21%) Horizontal Interferential Sham
and diclofenac (15%). Analgesic con- therapy therapy Horizontal
sumption was categorized as less than
twice a week, 3 to 6 times per week, Gender n. M/F 10/35 10/35 6/24
and daily. This information was col- Age mean (SD) 70.1 (7.3) 71.1 (7.9) 72.2 (9.1)
lected for the week preceding treatment Vertebral fractures n. 2 2 2 1
n. 3 6 5 5
and for week 14. The treatment codes n. > 3 22 23 14
were given to a single physiotherapist Degenerative disk disease 15 15 10
who administered all electric stimula- VAS baseline mean (SD) 7.9 (1.7) 8.2 (1.0) 8.1 (1.6)
tion therapies. The patients were kept Backill baseline 25.5 (6.0) 24.4 (6.5) 21.6 (6.4)
blind to treatment assignment, as were
the two physicians who evaluated the Analgesic consumption/week %
patients and administered the question- ≤ 2 times 33.3 35.6 48.3
3-6 times 44.4 40.0 40.0
naires. In order to assure the best possi- ≥ 7 times 22.2 4.4 11.7
ble blindness to treatment, we excluded
536Electric therapies and chronic low back pain / A. Zambito et al.
Fig. 2. Proportion
of patients in whom
the use of analges-
ic medications de-
creased during the
last week of obser-
vation in compari-
son to pre-treatment
week, in the 3
groups of patients
The rate of improve-
ment observed in
the HT group were
significantly greater
(p = 0.05) than that
observed in the
sham HT group.
Fig. 1. Percentage changes (mean and standard observations but also for the larger randomized trial, Werners et al. (27)
error) in functional (upper panel) and pain score variability of the changes. compared IFT and lumbar traction for
(lower panel) in the 3 groups of patients. The low back pain. They reported a similar
Backill scores were significantly improved at all
time points in all patients. A significant differ- Discussion reduction in disability and pain, sug-
ence (*= p < 0.05) between the Horizontal Thera- The current randomized controlled trial gesting that both treatments are equally
py (HT) group and the sham HT group was showed an initial significant and equal effective. However, it is also likely that
found at week 14.
improvement over baseline in all treat- the improvement simply represents the
The time points where the percent changes in
VAS score observed in the two active groups sig- ment groups including the sham treated natural history of low back pain rather
nificantly differed from those of control group patients for both functional and pain than any benefit from the treatments.
are highlighted with *(p < 0.01). scores. This clearly emphasizes the The results of this latter study remain
indispensable need for a proper control inconclusive because it lacked a place-
The use of analgesic medications sig- group for this type of clinical trial. Dur- bo control. Hurley et al. (28) evaluated
nificantly improved at week 14 versus ing the subsequent weeks the results the effectiveness of 2 electrode place-
pre-treatment assessment only in the for both outcomes tended to diverge ment techniques of IFT, i.e., “IFT
HT group and the proportion of between active and sham treated painful area” and “IFT spinal nerve” in
patients who improved (57.8%) was groups, although the Backill functional subjects with acute low back pain.
significantly greater (p = 0.05 by χ2 score continued to improve also in con- They showed the superiority of the
test) than that observed in the sham HT trol patients. However, this finding spinal nerve root technique over the
group (36.6%) (Fig. 2). may be attributed to the stretching painful area technique in reducing
The significance of all these findings exercise program carried out by all functional disability, but no differences
did not change when each outcome patients (26). were reported in pain score between the
value was adjusted for age, gender, The overall analysis of the results pro- 2 active groups and the control group.
underlying cause of CLBP (degenera- vides evidence that regimens of both Thus, both previous studies with IFT
tive disk disease and number of previ- IFT and HT treatments are significantly were unable to provide clear evidence
ous vertebral fractures) and baseline more effective than placebo, even of efficacy on low back pain. However,
VAS and Backill score (data not though over a limited lag time (12 several methodological differences are
shown). weeks). The difference versus the apparent between these and our study.
We also examined the treatment out- control group becomes apparent and Firstly, we used only subjects with
comes separately for the two main then significant only during the post- chronic low back pain (CLBP). In the
group of patients (degenerative disk treatment follow-up, when the effects two previous studies the recruited
disease and number of previous verte- in the sham HT group are wearing off patients suffered from acute low back
bral fractures, data not shown). (Fig. 1). pain, which is more likely to undergo a
The mean changes in the osteoporotic The HT therapy was more often signif- process of spontaneous recovery thus
group were superimposable as well as icantly different from the control group hiding the effect of any treatment (29).
the level of the between groups statisti- and somewhat more effective than IFT Secondly, our study is the first random-
cal significance (HT versus shame for all outcomes but the differences ized double-blind investigation ade-
HT), despite the smaller number of between the two active groups never quately powered to detect changes in
patients. In the osteoarthritis group the reached a statistical significance. pain. The patients were selected in
changes remained equally the same but To our knowledge, this is the first clini- order to achieve the best compliance to
none of them reached a statistical sig- cal trial on HT and, for some aspects, the protocol, i.e., living close to our
nificance, for the small number of the most accurate on IFT. In their out-patient clinics, no compelling
537Electric therapies and chronic low back pain / A. Zambito et al.
professional commitments, strongly the very high compliance of the study 6. HURLEY DA, MINDER PM, MCDONOUGH SM,
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