We bring to your attention a new website where you can buy priligy australia at a low price with fast delivery to Australia.
Effect of bemer magnetic field therapy on the level of fatigue in patients with multiple sclerosis: a randomized, double-blind controlled trial
THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINEVolume 15, Number 5, 2009, pp. 507–511ª
Mary Ann Liebert, Inc.
Effect of BEMER Magnetic Field Therapy on the Level
of Fatigue in Patients with Multiple Sclerosis:
A Randomized, Double-Blind Controlled Trial
Joachim Piatkowski, M.D.,1 Simone Kern, Ph.D.,2 and Tjalf Ziemssen, M.D.2
Objectives: Electromagnetic field therapy has been reported to be beneficial in patients with multiple sclerosis(MS) with significant fatigue. This study was designed to evaluate the long-term effects of Bio-Electro-Magnetic-Energy-Regulation (BEMER) on MS-related fatigue.
Design: This was a monocenter, patient- and rater-blinded, placebo-controlled trial.
Patients: There were 37 relapsing-remitting patients with MS with significant fatigue in the study.
Intervention: The intervention consisted of BEMER magnetic field treatment for 8 minutes twice daily incomparison to placebo for 12 weeks.
Outcome measures: The primary outcome criterion was change in the Modified Fatigue Impact Scale (MFIS)between baseline and 12 weeks. The secondary outcome criteria were changes of the Fatigue Severity Scale (FSS),a general depression scale–long version (ADS-L), Multiple Sclerosis Functional Scale (MSFC), and the ExpandedDisability Status Scale (EDSS).
Results: There was evidence of a significant difference of MFIS value (primary outcome criterion) after 12 weeksin favor of the verum group (26.84 versus 36.67; p ¼ 0.024). In addition, FSS values were significantly lower in theverum group after 12 weeks (3.5 versus 4.7; p ¼ 0.016). After 6 weeks’ follow-up, verum and placebo groups didnot differ in experienced fatigue (MFIS, FSS). Regarding the subscales of the MFIS, there was a significantdecrease in physical ( p ¼ 0.018) and cognitive ( p ¼ 0.041), but not in psychologic subscales only in the verumgroup regarding the timepoints baseline and 12 weeks. BEMER therapy was well tolerated.
Discussion: In this pilot study, we were able to demonstrate a beneficial effect of BEMER intervention on MSfatigue. As this was only a pilot study, trials with more patients and longer duration are mandatory to describelong-term effects.
with magnetic resonance imaging markers of disease activity,although it does seem to increase when the patient experi-
atigue is among the most common symptoms of mul- encesrelapses.2,4Fatigueisamajorcauseofunemploymentin
tiple sclerosis (MS), affecting at least 75% of patients,1 for
patients with MS.5–7 The etiology and pathophysiology of
many of whom it constitutes one of the worst and most dis-
MS-related fatigue remain unknown. Studies have failed to
tressing features.2 Fatigue is reported in all clinical pheno-
demonstrate an association between MS-related fatigue and
types of MS and affects patients of all ages.3 This symptom is
the level of disability, clinical disease subtype, or gender.8
an integral part of the disease process that is usually present at
Imaging studies using positron emission tomography suggest
the time of diagnosis and in some cases represents one of the
that fatigue in MS is related to hypometabolism of specific
reasons for which patients originally consult a neurologist.
brain areas, including the frontal and subcortical circuits.9
Fatigue is not closely related to physical signs of disability or
Different components of fatigue have been described such as
1Neurological Outpatient Center Reichenbachstrasse, Dresden, Germany.
2MS Center Dresden, Department of Neurology, University of Technology Dresden, Dresden, Germany.
motor and cognitive fatigue and lassitude. Management
bo); all 4 had no time left for the two applications per day.
strategies include medications, exercise, and behavioral ther-
Data analysis was therefore restricted to the remaining 37
apy.10 There have been reports on positive effects of immu-
patients with complete data sets because for the lost 4 pa-
nomodulatory drugs on fatigue.11 However, the efficacy of
tients, no follow-up data were available. Female and male
patients between 18 and 65 years were enrolled in the study
In addition to pharmacological interventions, non-
when they (1) had relapsing-remitting MS as defined by Poser
pharmacological treatments including yoga, aerobic exer-
et al.,19 (2) accepted the informed consent, and (3) had sig-
cises, cooling therapy, and energy conservation techniques
nificant fatigue as reported by the patient. Reasons to refuse
have been used sucessfully. A recent meta-analysis summa-
were (1) previous therapy with pulsed electromagnetic fields,
rized promising data on electromagnetic field devices12: Ri-
(2) acute relapse of MS within the last month as we were
chards et al. and Lappin et al. demonstrated a positive effect
interested in the effect of magnetic field therapy on chronic
of low-level pulsed, electromagnetic field devices worn by
fatigue that can be interfered with by an acute relapse, (3)
the patients.13,14 Unfortunately, there were no long-term data
psychiatric or neurological disorders other than multiple
available. Although Mostert and Kesselring showed disap-
sclerosis, (4) actual treatment with amantadine, aminopyr-
pointing data on pulsed magnetic field therapy as an addi-
idine, or modafinil as drug therapy for fatigue to avoid in-
tional effect of a multimodal neurological rehabilitation
terference of anti-fatigue effects of drugs and magnetic field
program on fatigue,15 Sandyk documented improved phys-
therapy or (5) pregnancy. Randomization to verum and pla-
ical and cognitive fatigue in case studies of patients with MS
cebo group was performed by block randomization. Patients
after a course of treatment.16,17 It is only hypothetical why
and physician=statistician were blinded. All patients were
there is a positive impact of magnetic field therapy on MS
told in the informed consent document that there was a 50%
fatigue. Factors such as energy metabolism, oxygen supply,
chance to receive placebo and verum treatment. All devices
and microcirculation are discussed.12 The tendency for pos-
looked identical and were numbered. The placebo-verum
itive results warrants further investigation using a double-
coding was only used for the final analysis. The success of
blinded, controlled protocol. There are different patterns
blinding was not evaluated, and patients were unblinded af-
of pulsed magnetic field therapies available. Bio-Electro-
Magnetic-Energy-Regulation (BEMER, Innomed Interna-
The BEMER therapy was used to stimulate by extremely
tional AG, Lichtenstein) therapy uses broadband, extremely
weak, low-frequency pulsed electromagnetic fields (with
weak, low frequent pulsed electromagnetic fields induced by
mean of 14 mT) induced by flexible, flat electric coils. The
flexible, flat electric coils.18 Although there have been sev-
BEMER signal consists of a series of half-wave-shaped sinu-
eral anecdotal positive reports with this device, no placebo-
soidal intensity variations. Starting out with low values, the
controlled, double-blinded study is currently available in the
intensity initially increases slowly and then drops again to a
value that, however, is located at a higher level within the
Our study was designed to evaluate the long-term effect of
impulse than the initial value. This sequence keeps repeating
BEMER therapy in patients with MS with significant fatigue in
itself, while the intensity variations gets denser and the drift
a typical outpatient setting: Patients with relapsing-remitting
from the zero line gradually increases. Correspondingly, the
MS and significant fatigue were randomized to BEMER or
ups and downs keep getting steeper. The intensity process
placebo treatment and were evaluated after 6 and 12 weeks
repeats itself 33.3 times per second. After 2 minutes, the
using different fatigue scales. We hypothesize that patients
magnetic field changes its polarity. The duration of the signal
with relapsing-remitting MS who use the BEMER for 8 min-
sequences was set empirically via a control device to a period
utes twice a day for 12 weeks, will experience improvement in
of 8 minutes. In this way, the magnetic field of the BEMER
fatigue, compared to patients who use a placebo device.
3000 systems is, in the first approximation, a typical pulsingconstant electromagnetic direct current field that is asym-metrical to the zero line. The BEMER device includes a control
device that produces the patented BEMER signal and that
The present study was a randomized, patient- and rater-
could be turned on=off by the patient. It is connected with an
blinded, placebo-controlled trial conducted in a neurological
all-metal mat that is hooked up to the control device via a
outpatient center in Dresden. The study lasted 3 months and
was performed between 2006 and 2007. The study protocol
For this study, patients with MS were asked to lie down
was approved by the international ethical committee Frei-
on the mattress for 8 minutes twice every day at their private
burg, Germany (EC 02=TS=06). It was conducted according
home. Compliance of the patient was controlled by a special
to the Declaration of Helsinki (Hong Kong Amendment) and
diary. In the treatment group (verum), the BEMER mattress
pertinent national legal and regulatory requirements. Prior to
was activated whereas in the control group (placebo), no
study entry, each patient provided written, informed consent
magnetic field was generated although there was the typical
and was free to withdraw from the study at any time for any
reason without consequences on the care provided.
Patients were evaluated at inclusion and after 6 and 12
Forty-one (41) ambulatory patients with clinically definite,
weeks of treatment at the same time of day (10 am). At each
relapsing-remitting MS were randomly assigned to treat-
visit, patients underwent a full neurologic assessment, any
ment with BEMER or to sham therapy twice a day over 3
relapses occurring since the previous visit were ascertained,
months. The sample size was calculated before using the
and disability was assessed with the Expanded Disability
software nQuery Advisor 6.0 (Statistical Solutions, Cork,
Status Scale (EDSS).20 Multiple Sclerosis Functional Com-
Ireland) with a power of 97% (two-sided test, a ¼ 0.05). A
posite (MSFC) was performed each time. Fatigue was as-
total of 4 patients were lost to follow-up (2 verum, 2 place-
sessed by the patient using the fatigue severity scale (FSS), a
Table 1. Demographic Characteristics of the Multiple
At baseline, both groups did not differ in terms of EDSS
Sclerosis Patients in the Verum and Placebo Group
(Student’s test: t ¼ 1.21; not significant (n.s.)), MSFC (Stu-dent’s t-test: t ¼ 0.7; n.s.), duration of disease (Student’s t-test:
t ¼ 1.10; n.s.) and ADS-L (Student’s t-test: t ¼ À1.23; n.s.).
Fatigue scores (MFIS, FSS) were slightly higher in the pla-
cebo group compared to the verum group, but this effect did
not reach statistical significance (Student’s t-test: MFIS:
t ¼ À1.36; n.s.; FSS: t ¼ À1.15; n.s.) (Table 2).
Primary outcome criterion: MFIS baseline versus
Regarding the primary endpoint of our study, there was
evidence of a significant difference of MFIS value after 12
Data are presented as mean Æ standard deviation. EDSS, ex-
weeks in favor of the verum group (26.84 versus 36.67; Stu-
panded disability status scale; MSFC, Multiple Sclerosis Functional
dent’s t-test for independent samples: MFIS12weeks: t ¼ À2.36;
Scale; GA, glatiramer acetate; IFN, interferon-b.
visual analogue scale scored from 0 (no fatigue) to 10
Secondary outcome criteria: Baseline versus 6 weeks’
(maximum possible fatigue), and with the Modified Fatigue
Impact Scale (MFIS)21 in its validated German translation.
This is a 21-item questionnaire that yields a total score
After 6 weeks’ treatment, verum and placebo groups did
ranging from 0 (no impact of fatigue) to 84 points (maximum
not differ in experiencing fatigue (Student’s t-test for inde-
impact of fatigue), as well as three subscales representing the
pendent samples; MFIS6weeks: t ¼ À1.38; n.s.; FSS6weeks:
physical (score range 0–36), cognitive (score range 0–40), and
t ¼ À2.03; n.s.) (Table 2). However, looking at changes in fa-
psychosocial (score range 0–8) dimensions of fatigue. De-
tigue over time, there was a decrease in fatigue measured by
pression was evaluated by the long German version of the
the FSS in the verum but not the placebo group after 6 weeks
Center for Epidemiologic Studies Depression Scale (CES-D)
compared to baseline (paired t-test: FSS6weeks=verum: t ¼ 2.68;
general depression scale–long version (ADS-L).22
p ¼ 0.015; FSS6weeks=placebo: t ¼ 0.98; n.s.) (Table 3). No differ-
Group differences in MFIS, FSS, MSFC, EDSS, and ADS-L
ences for the MFIS or MFIS subscales (physical, cognitive,
scores between verum and placebo groups at the different
psychologic) over time were observed for either group (paired
timepoints were evaluated by Student’s t-test for indepen-
t-test: MFIS6weeks=verum: t ¼ 1.14; n.s.; MFIS6weeks=placebo:
dent samples. Changes in fatigue scores over time were
statistically assessed by paired t-tests for the placebo and the
Self-rated depressive symptoms by the CES-D did not dif-
verum group, respectively. Differences in gender group
fer between groups after 6 weeks’ treatment (Student’s t-test
composition were assessed with a w2 test. All comparisons
for independent samples: ADS-L6weeks: t ¼ À0.76; n.s.). There
were two-tailed and a p value of <0.05 was taken as being
was also no change in depressive symptoms expression over
time in either group (paired t-test: ADS-L6weeks=verum: t ¼ 0.33;
The BEMER devices were kindly supplied by Innomed
n.s. = ADS-L6weeks=placebo: t ¼ 0.45; n.s.).
International AG, Lichtenstein. No additional support was
Secondary outcome criteria: Baseline versus
In addition to significant different fatigue ratings by MFIS
between the verum and placebo groups, there was evidence
Study population and baseline characteristics
for a significant difference of FSS value after 12 weeks’ treat-
Baseline demographic characteristics are presented in
ment in favor of the verum group (Student’s t-test for inde-
Table 1. Verum and placebo groups did not statistically differ
pendent samples: FSS12weeks: t ¼ À2.53; p ¼ 0.016). In the
in terms of age or gender group composition.
verum group but not in the placebo group, there was a
Table 2. Changes of Modified Fatigue Impact Scale ( MFIS) Overall Score and as well as Physical, Cognitive,
and Psychologic Subscores in Verum and Placebo Group at Baseline, 6 Weeks, and 12 Weeks
Changes of MFIS overall score. Data are presented as mean Æ standard deviation (SD).
Table 3. Changes of MSFC, EDSS, MFIS, FSS, and ADS-L in Verum and Placebo Group at Baseline,
Data are presented as mean Æ standard deviation (SD).
MSFC, Multiple Sclerosis Functional Scale; EDSS, Expanded Disability Status Scale; MFIS, Modified Fatigue Impact Scale; FSS, Fatigue
Severity Scale; ADS-L, general depression scale–long version.
significant decrease in perceived fatigue over this 12-week
following physical activity by extracranially applied elec-
period (paired t-test; FSS12weeks=verum: 3.87; p ¼ 0.001;
MFIS12weeks=verum: t ¼ 3.12; p ¼ 0.006; FSS12weeks=placebo: 1.50;
A recent meta-analysis summarized beneficial effects of
p ¼ n.s.; MFIS12weeks=placebo: t ¼ 0.53; p ¼ n.s.). Regarding the
electromagnetic fields on MS fatigue, but recommended
subscales of the MFIS, there was a significant decrease in
physical (paired t-test: MFIS=phys12weeks=verum: t ¼ 2.6; p ¼
Other experiments have already investigated the effect of
0.018; MFIS=phys12weeks=placebo: t ¼ 0; n.s.) and cognitive
electromagnetic fields on MS fatigue so far. Lappin et al.
demonstrated a reduction of MS fatigue by 0.5 points on a
MFIS=cog12weeks=placebo: t ¼ 0.43; p ¼ n.s.) but not in psycho-
modified five-item scale out of the MS Quality of Life In-
logic subscales (paired t-test: MFIS=psy12weeks=verum: t ¼ 1.83;
ventory by wearing a small portable pulsing electromagnetic
n.s.; MFIS=psy12weeks=placebo: t ¼ 1.44; n.s.) only in the verum
device next to the skin over the brachial plexus 24 hours a
group regarding the timepoints baseline and 12 weeks’
day for 4 weeks.14 Expressed in relative terms, this was a
decrement of fatigue by roughly 20%. The placebo effect of
Self-rated depressive symptoms by CES-D did not differ
the sham intervention in their study was 0.36 points (about
between groups after 12 weeks’ treatment (Student’s t-test for
14%). A preliminary study of the same study group with 30
independent samples: ADS-L12weeks: t ¼ 1.35; n.s.). There was
patients with the same device used 24 hours per day over a
a tendency for decreased depressive symptoms compared to
2-month period also demonstrated a beneficial effect of
baseline in the verum group, but this effect did not reach
pulsed magnetic field therapy on a combined performance
statistical significance (paired t-test: ADS-L12weeks=verum:
scale rating for bladder control, cognitive function, fatigue
t ¼ 2.03; (0.058=n.s.)=ADS-L12weeks=placebo: t ¼ 0.89; n.s.).
level, mobility, spasticity, and vision.13
There were no significant side-effects during verum and
In contrast, Mostert and Kesselring used a device (mag-
netic cell regeneration system by Santerra) that was compa-rable to the BEMER system as it was applied for 16 minutestwice daily. They were not able to demonstrate a beneficial
effect of pulse electromagnetic field therapy as an additional
Our study was focused on effects of a new type of pulsed
component to a multimodal neurologic rehabilitation pro-
low-frequency electromagnetic fields of the BEMER 3000
gram on fatigue.15 In comparison to our study, the level of
device on MS fatigue after 6 weeks and 12 weeks. The pa-
fatigue was slightly higher as measured by the FSS (5.5).
tients were evaluated by a panel of different questionnaires
Unfortunately, other studies could not be compared re-
(MFIS, FSS, ADS-L) in addition to MSFC and EDSS testing.
garding the baseline fatigue level because they used other
Using a randomized placebo-controlled protocol, we were
scales. Because Mostert and Kesselring described a wide
able to demonstrate a modest, but statistically significant
variability of measurements using the visual analogue scale,
advantage for the verum treatment group concerning an ef-
we decided to focus our evaluation of MS fatigue only on
fect on the MFIS and FSS over a 3-month period. Although
FSS and MFIS scales. In contrast to this study, we measured
both groups showed a decrease of fatigue over the inter-
fatigue level not directly after the application of electro-
vention time, MFIS score was significantly lower in the
magnetic field therapy, but in the study center always at 10
verum than in the placebo group 3 months later, which re-
am. Our patients were not enrolled in a specific rehabilitation
flects a statistical advantage of the BEMER treatment ac-
program, which may have additional positive effects on MS
cording the predefined primary outcome criteria.
fatigue that may be confounded in their study. Mostert and
There is growing evidence in the literature of a beneficial
Kesselring have already described that a special rehabilita-
effect of magnetic field therapy on different MS symptoms
tion program with short-time exercise treatment was able to
such as fatigue, bladder control, spasticity, and quality of life.
reduce MS fatigue in a significant way.25
Nielsen and Sinkjaer reported a reduction of spasticity by
Of course, there are statistical limitations of this study.
magnetic stimulation over the thoracic myelon,23 while
Although this study was a randomized, placebo-controlled
Sandyk reported cases of prompter recovery from fatigue
trial, the number of participants was limited, with only 19=18
patients in each treatment arm. Other studies investigated
12. Neill J, Belan I, Ried K. Effectiveness of non-pharmacological
comparable numbers of patients13,15; only Lappin et al. in-
interventions for fatigue in adults with multiple sclerosis,
vestigated more than 55 patients per group, but only for 4
rheumatoid arthritis, or systemic lupus erythematosus: A
weeks.14 Larger trials on this issue are needed in order to
systematic review. J Adv Nurs 2006;56:617–635.
confirm the findings from this pilot study. Again, it is not
13. Richards TL, et al. Double-blind study of pulsing magnetic
possible to compare the different devices, as the physiology
field effects on multiple sclerosis. J Altern Complement Med
of magnetic field therapy is not well known. Magnetic field
therapy is used in a lot of clinical settings. Unfortunately,
14. Lappin MS, Lawrie FW, Richards TL, Kramer ED. Effects of
scientific data on mechanism and so on are still missing. We
a pulsed electromagnetic therapy on multiple sclerosis fa-
are beginning to investigate physiologic changes induced by
tigue and quality of life: A double-blind, placebo controlledtrial. Altern Ther Health Med 2003;9:38–48.
15. Mostert S, Kesselring J. Effect of pulsed magnetic field ther-
apy on the level of fatigue in patients with multiple sclerosis:
A randomized controlled trial. Multiple Sclerosis 2005;11:
In this pilot study, we were able to demonstrate a bene-
ficial effect of BEMER therapy on MS fatigue. Although we
16. Sandyk R. Treatment with weak electromagnetic fields im-
recognized a placebo effect, there was a statistically signifi-
proves fatigue associated with multiple sclerosis. Int J Neu-rosci 1996;84:177–186.
cant benefit for treated patients after 12 weeks. From our
17. Sandyk R. Immediate recovery of cognitive functions and
personal experience, MS patients suffering from MS fatigue
resolution of fatigue by treatment with weak electromag-
can benefit from electromagnetic field therapy. Because de-
netic fields in a patient with multiple sclerosis. Int J Neurosci
vices for pulsed electromagnetic therapy like BEMER are
quite expensive, we recommend individual tests for several
18. Walther M, Mayer F, Kafka W, Schutze N. Effects of weak,
weeks to see whether there is an individual benefit for the
low-frequency pulsed electromagnetic fields (BEMER type)
MS patient with significant fatigue.
on gene expression of human mesenchymal stem cells andchondrocytes: An in vitro study. Electromagnetic Biol Med
19. Poser CM. Clinical diagnostic criteria in epidemiological
No competing financial interests exist.
studies of multiple sclerosis. Ann NY Acad Sci 1965;122:506–519.
20. Kurtzke JF. Rating neurologic impairment in multiple scle-
rosis: An expanded disability status scale (EDSS). Neurology
1. Freal JE, Kraft GH, Coryell JK. Symptomatic fatigue in
multiple sclerosis. Arch Phys Med Rehabil 1984;65:135–138.
21. Multiple Sclerosis Council for Clinical Practice Guidelines.
2. Fisk JD, Pontefract A, Ritvo PG, et al. The impact of fatigue
Fatigue and Multiple Sclerosis: Evidence-Based Management
on patients with multiple sclerosis. Can J Neurol Sci 1994;
Strategies for Fatigue in Multiple Sclerosis. Washington, DC:
Paralyzed Veterans of America, 1998:1–33.
3. Ziemssen T. Multiple sclerosis beyond EDSS: Fatigue and
22. Hautzinger M. Die CES-D Skala: A depression scale for
depression. J Neurol Sci 2008;273:S32–S35.
evaluation of general populations [in German]. Diagnostika
4. Vercoulen JH, et al. The measurement of fatigue in patients
with multiple sclerosis: A multidimensional comparison
23. Nielsen JF, Sinkjaer T. Long-lasting depression of soleus
with patients with chronic fatigue syndrome and healthy
motoneurons excitability following repetitive magnetic
subjects. Arch Neurol 1996;53:642–649.
stimuli of the spinal cord in multiple sclerosis patients. Mul-
5. Smith MM, Arnett PA. Factors related to employment status
changes in individuals with multiple sclerosis. Multiple
24. Sandyk R. Resolution of sleep paralysis by weak electro-
magnetic fields in a patient with multiple sclerosis. Int J
6. Krupp LB. Fatigue in multiple sclerosis: Definition, patho-
physiology and treatment. CNS Drugs 2003;17:225–234.
25. Mostert S, Kesselring J. Effects of a short-term exercise
7. Jackson MF, Quaal C, Reeves MA. Effects of multiple sclerosis
training program on aerobic fitness, fatigue, health percep-
on occupational and career patterns. Axone 1991;13:16–17,
tion and activity level of subjects with multiple sclerosis.
Multiple Sclerosis 2002;8:161–168.
8. Bakshi R. Fatigue associated with multiple sclerosis: Diag-
9. Filippi M, Rocca MA. Toward a definition of structural and
functional MRI substrates of fatigue in multiple sclerosis. J
10. Lee D, Newell R, Ziegler L, Topping A. Treatment of fatigue
in multiple sclerosis: A systematic review of the literature.
11. Ziemssen T, Hoffmann J, Apfel R, Kern S. Effects of glatiramer
acetate on fatigue and days of absence from work in first-time
treated relapsing-remitting multiple sclerosis. Health QualityLife Outcomes 2008;6:67.
E-mail: [email protected]
CURRICULUM VITAE Harrison C. Spencer, MD, MPH, DTMH Current Position: President and CEO Association of Schools of Public Health 1101 15th Street NW Suite 910 Washington, DC 20005 Telephone, Fax & e-mail: 202-296-1099 (Office tel) 202-296-1252 (Office fax) (e-mail) Home Address 2425 L Street NW Apt. 807 Washington, DC 20037 Education: Haverford College
Lumbar Epidural Steroid Injections for Low Back Pain and Sciatica Epidural steroid injections (ESIs) are a common treatment option for many forms of low back pain and leg pain. They have been used for low back problems since 1952 and are still an integral part of the non- surgical management ofThe goal of the injection is pain relief; at times the injection alone is sufficient to provi