PBM - the way to established medicine
Clinical
research on the effects of PBM is based on the usual scientific
procedures of human medicine studies. A large number of high-quality
meta-analyses and RCTs according to the standards of evidence-based
medicine are available for the application areas of pain therapy and
wound treatment, proving the pronounced therapeutic efficacy of PBM.
In
addition, there are now several studies on the mechanisms of action of
photobiomodulation at the molecular and cellular level.
However, many physicians are still unaware of photomedicine and the state of research is hardly acknowledged.
1. State of research
Clinical Research
The available
literature on the mechanisms of action of PBM and their effects in
various indications in the Pubmed database today comprises more than
4000 studies. While the methodological quality of PBM studies of the
last century was often still low, the majority of publications since
then have been based on scientific standards. An evaluation of the
literature (reviews, meta-analyses) was repeatedly carried out for
defined areas of application.
Today, there is considerable study
evidence for defined indications for which the pain-relieving and
anti-inflammatory effect of PBM is documented in acute and chronic
painful-inflammatory musculoskeletal conditions such as neck pain,
epicondylitis, arthritis and tendinopathies. There is also a large
number of individual studies on a wide variety of clinical pictures,
which often describe a benefit, but without being able to make reliable
statements on statistical significance due to the usually small number
of cases.
For a comprehensive evaluation of the existing literature,
great efforts are generally still necessary (Note: In the member area
you will also find a research archive).
Example:
Evidence for the effectiveness of PBM in wound healing processes and in pain conditions of the musculoskeletal system
We
document studies for two essential claims of PBM: the promotion of
wound healing and pain relief. Based on a minimum number of different
quality criteria, we selected 2 meta-analyses (2004) and 7 randomized
controlled trials (2009-2012) for wound healing and 6 meta-analyses
(2004-2012) and 11 RCTs (2009-2012) for pain relief. We found highly
significant therapeutic effects for both forms of treatment:
For the promotion of wound healing, the best results have been found
in chronic wounds with wound healing disorders. In wounds exposed to
permanent pressure (e.g. decubitus ulcers), the results were
significantly weaker.
The best results for pain relief could be found
for pain states of the musculoskeletal system. Thereafter, indications
such as neck pain, tendinopathies, epicondylitis, osteoarthritis of the
knee or temporomandibular dysfunctions are the main areas of application
of PBM.
Mechanisms of action of PBM
The
mechanisms of photobiomodulation at the intracellular level have only
recently begun to be better understood. Until recently, there were no
conclusive explanations as to how weak light, which cannot even lead to a
significant warming of the tissue, is able to influence inflammations,
infections, edemas or the healing process of chronic wounds.
Particularly
in in vitro studies and animal models, the individual primary effects
triggered by the low-level laser in the cell interior have recently been
described in ever greater detail.
2. PBM-specific research handicaps
The discrepancy between clinical studies with high evidence and
studies which confirm that PBM has only minor effects is enormous in the
case of PBM. With PBM, paradoxically, it is precisely the extensive
study situation that has led to much confusion.
The project to
analyse scientific studies on PBM according to a standardised procedure
involves various difficulties and the danger of distortions with regard
to effects. The reason for this is the PBM-specific large variability of
the study designs, the application techniques, the radiation dosage and
the investigated indications in the existing scientific literature on
PBM.
Variable intervention modes
Studies with
different intervention modes are difficult to compare. The
laser-specific treatment parameters and the therapeutic techniques of
PBM vary greatly:
Laser therapy is applied (1) with different laser
devices, (2) different dosages, (3) different application techniques,
(4) different weightings (solitary measure or add-on therapy), (5) a
different number of total treatments and with different treatment
intervals.
The complexity of the variables makes standardization difficult.
Laser systems work with different wavelengths and output powers. There are HeNe (Helium-Neon), GaAs (Gallium-Arsenide) and GaAlAs (Gallium-Aluminium-Arsenide) which can also be combined in one device. Their effectiveness tends to vary depending on the application. In the 90s lasers had an output power of 1-5 mW, higher powers of up to 30 mW were very rare. Today, lasers have significantly higher output powers of up to 500 mW or even more. Therefore, studies on PBM belong to different "laser generations", the results of which can hardly be compared.
The proportion of studies in the scientific literature on PBM for which laser devices with relatively low output powers were used is large. Only in the last 10 years have lasers with up to 100 times higher output power been increasingly used and evaluated. The effectiveness of the PBM for the different indications depends to varying degrees on the power density applied. Higher effective power densities can have an inhibitory effect (e.g. in certain stages of wound healing) or be decisive for an effect (e.g. in painful inflammations of large joints). Over- or underdoses can also be the reason for poor results in studies.
Laser therapy or PBM can be applied "automatically" with the help of "scanners" or tripods - or with hand-guided laser instruments that allow direct skin contact and make the therapy much more effective. Laser therapy can be used for local irradiation (e.g. joints, damaged skin areas etc.) or for stimulation of trigger, pain and/or acupuncture points and other reflex areas. It can target superficial tissue areas (e.g. scratch wounds) or deeper body layers (e.g. transmastoid irradiation of the inner ear). It can also be used invasively (intravenous, interstitial and intraarticular laser therapy). Different treatment techniques are often mixed.
The type of intervention with PBM also reflects their different
therapeutic weighting in different clinical pictures. In many cases, PBM
is not compared with any intervention (placebo). In some meaningful
clinical studies, PBM is compared with established conventional
interventions. Thus, PBM is not tested against no intervention
(placebo), but the effects of PBM are compared with the effects of a
standard medical therapy procedure.
In some studies, the effects of
PBM are investigated as an add-on therapy to a standard intervention.
The standard intervention (e.g. wound therapy according to guidelines)
plus co-intervention (simultaneous therapy) with PBM is compared with
the standard intervention alone. For example, in severe chronic wounds
or severe pain, PBM does not claim "non-inferiority" compared to
standard therapies according to the guidelines. It merely claims a
highly effective add-on therapy to the standard therapy with additional
benefits such as an acceleration and activation of wound healing
(endpoint: time until wound closure) and/or a significant additional
reduction in pain (endpoint: e.g. VAS).
The total number of treatments for a therapeutic effect with PBM can
vary greatly depending on the indication. For example, a single
treatment for a superficial skin wound can have a noticeable effect.
Chronic wounds, on the other hand, usually react only after a few
treatments with a noticeable and visible effect and the therapy should
be carried out over longer periods of time.
Treatment intervals can
also be adequate or inappropriate. In the case of acute complaints or at
the start of treatment, for example, a treatment frequency of 1x/week
is usually inadequate, whereas in the case of chronic complaints it may
be sufficient.
In practice, the number and interval of treatments are
adapted to the individual situation. They depend on how well the
complaints respond to the treatment in the individual case. In a
clinical examination, however, this individualization is not possible
because of the necessary standardized intervention protocol.
3. Incomplete studies - Wrong dosage
A key parameter for effective laser therapy is dosage. Especially in
the treatment of pain, an effective minimum dose is crucial. The minimum
dose is the dose at which a therapeutic effect can be proven. It varies
depending on the indication and can be relatively low (e.g. 3-4 J for a
herpes wound of the lip) or very high (e.g. 20 J for an alveolitis).
One
result of some meta-analyses of pain therapy with PBM around the turn
of the century was that it could be deduced from many studies with no
proof of efficacy that the cause was too low a dosage. The
dose-dependence of the effects of PBM is highly significant.
Nevertheless,
studies with negative proof of efficacy are often cited or included in
reviews whose lack of evidence can be attributed to underdoses.
4. Conclusions and recommendations of the WALT
Photomedical experts see the decisive cause for the still weak
acceptance of PBM among physicians in the often inadequate study
protocols. Even though the variability of study parameters in PBM is
very complex, the RCTs for PBM with positive evidence can be used to
derive precise indication-oriented application protocols with regard to
adequate dosage, application technique and duration etc. Jan Tunér
(Board member of the World Association of Laser Therapy / WALT) and Lars
Hode (President of the Swedish Laser-Medical Society) write in their
review of the state of the art in laser photo medicine ("The New Laser
Therapy Handbook", Prima Books 2010, ISBN-13 978-91-976478-2-3, p. 580)
that "ironically, the most serious shortcoming in many studies on laser
therapy was that the therapy itself was not given attention". They
believe that by improving study designs and accurately documenting all
PBM-specific variables used in an investigation, laser therapy will be
recognized to the same extent as laser surgery is today.
The World
Association for Laser Therapy (WALT) has published guidance and
recommendations on its website to help scientists and physicians design
and conduct clinical trials on PBM.
5. Other handicaps
The weak response to the progress made in photomedicine by orthodox doctors is also due to their incorrect location. What is popular, simple and risk-free to use and helps with many complaints is often viewed sceptically and it is assumed that there is little evidence. The following special features of PBM are certainly unusual for many orthodox physicians: