Assessing the efficacy of pain therapies
Patients’ expectations and responses play decisive role
When assessing the efficacy of pain therapies, a vital factor is whether they live up to patients’ high
expectations, according to Dr Andrew Moore of Oxford University, a speaker at the Congress of the
European Pain Federation EFIC in Vienna. Another key consideration is finding out at an early stage
whether patients respond to a particular course of treatment, as a swift response is a predictor of the
long-term success of therapy.
Vienna, 3 September 2015 – Evaluation of scientific evidence on whether pain therapy is effective
should take patients’ expectations and sensations into account. “The outcome – in other words, the
effectiveness of the therapy in treating a specific patient – is an important indicator of the usefulness of
a particular course of treatment,” Dr Andrew Moore (Oxford University) told the 9th Congress of the
European Pain Federation EFIC in Vienna. Over 4,000 experts from all over the world are in the
Austrian capital to discuss the latest trends in pain research and therapy. The motto of the EFIC
Congress is “Translating evidence into practice”. A number of sessions featuring top specialists,
including a refresher course given by Dr Moore, are looking at ways in which scientific evidence can
be integrated into everyday treatment.
Expectations are vital to assessing the success of therapy
Dr Moore has over two decades of experience in the systematic scientific evaluation of the
effectiveness of pain treatments. As he explained: “In contrast to other, seemingly objective indicators,
outcome analysis also looks at patients’ expectations of the therapy. The way in which pain relief is
experienced differs between individuals, and patients usually have high expectations.” In fact,
sufferers of chronic pain expect significant pain relief of between 50 and 70 percent. Patients demand
substantial alleviation of the side effects of chronic complaints, such as sleep disorders, fatigue and
depression, and an improvement in their quality of life. There is also a desire to break free of the
limitations on physical capacity, so that they can return to work. “Whether or not the treatment comes
close to meeting these expectations has enormous economic implications. If severe chronic pain
cannot be reduced to a subjectively bearable level, patients face the threat of incapacity and early
retirement,” Dr Moore warned.
Responder or non-responder: how patients react to therapy
Effective pain therapy can now fulfil a wide range of patient requirements – provided the right course
of treatment is chosen. Another important distinction used in evaluating therapeutic efficacy is
between responders and non-responders: which patients feel the full effect of the treatment and which
see little or no impact? How can patients be reliably assigned to one group or the other?
The extent to which therapeutic outcomes differ between individual patients was highlighted, inter alia,
in a groundbreaking study by Yarnitsky et al (2012): For instance, those who are unable to activate a
reduction in conditioned pain modulation (CPM) respond far better to duloxetine than those in whom
CPM is activated.
Early response points to long-term success
Information on responders and their characteristics is still thin on the ground. There are many cases of
patients who do not fit the model and do not experience a significant reduction in pain, even though
they should be expected to classify as responders. However, a series of eye-catching recent insights
could have an impact on pain therapy in the future. Firstly, responders with acute and chronic pain
show the same response to a particular form of therapy. In addition, it has been found that responders
can usually be identified at an early stage of treatment. This means that early response is a predictor
of the long-term success of a course of therapy, while non-response is a reliable indicator that
treatment should be stopped. “If someone does not react quickly, we can stop the treatment at a
relatively early stage and try a different approach. This saves patients from undergoing long drawn-out
treatment that only results in potential side effects,” Dr Moore concluded. With this in mind, he
suggests reviewing conventional procedures for testing the efficacy of pain medication, as well as
drawing up recommendations that allow doctors to correctly identify responders in practice.
Fewer medications, improved effectiveness
Another study (Demant et al, 2014) demonstrates how important accurate classification can be. The
results showed that irritable nociceptors are central to the effectiveness of painkillers such as
oxcarbazepine, which act as sodium channel inhibitors. It was found that an average of seven
medications were required to achieve pain reduction of over 50 percent in the patients observed in the
study. Those with irritable nociceptors needed only four different drugs, but for those without the
number was 13. “These findings underline the importance of accurate patient phenotypes. The clearer
the patient profile, the fewer medications are required,” Dr Moore explained. This would also help to
cut unnecessary spending on treatment, as well as prompting a reappraisal of current practice in
relation to drug availability.
Many countries in Europe have formularies – positive lists of pharmaceuticals for which public funds
bears the costs or negative lists which exclude certain medications from the services provided by
health insurance funds or health authorities. Most of these bodies use evidence-based criteria when
compiling such lists. However, Dr Moore sees a problem in such limited formularies. Speaking at the
EFIC Congress he put forward an alternative concept: “I am in favour of specifying the number of
medications that have to be included in a formulary, so that all suitable patients can receive effective
treatment for certain types of pain.”
Sources: EFIC Abstract C09 Refresher Courses: Moore, Effectiveness and adverse effects of pain medications:
Lessons from 20 years experience of systematic reviews in pain management; Moore et al. Duloxetine use in
chronic painful conditions – individual patient data responder analysis. European Journal of Pain 2014;18:67-75
EFIC Press Office
B&K - Bettschart&Kofler Kommunikationsberatung
Dr. Birgit Kofler
Ph.: +43 1 3194378; +43 676 6368930; +49 172 7949286
E-mail: kofler@bkkommunikation.com