The problem of chronic pain is relevant to health because of its widespread occurrence. Approximately 55% of people in the world suffer from chronic pain. Recently, the results of a study of chronic pain syndrome in Europe with the participation of 16 countries were published. Questioning was carried out only in individuals with pain of moderate and strong intensity (5 points or more when evaluating on a 0-10-point scale). It turned out that in Europe, the prevalence of pronounced chronic pain syndromes ranged from 11 to 30% and averaged 19%. The average duration of this pain was 7 years, and the vast majority suffered more than two years. Every fifth patient lost his job, and every fifth patient developed depression associated with pain.
Especially often chronic pain syndromes accompany diseases of the musculoskeletal system. Thus, the leading causes of chronic pain were arthritis and osteo-arthritis (34%), pathology of the intervertebral disc (15%), rheumatoid arthritis (8%). The pains were most often localized in the knee (16%) and shoulder joints (9%), as well as in other joints (10%), in the lower back (24%). The vast majority of respondents (78%) tried to take prescribed medications, and 52% continued to be treated at the time of interviewing. At the same time, two thirds of the patients reported that the pain was not sufficiently suppressed and two thirds were ready to try new drugs. These data convincingly show the magnitude of the problem of chronic pain and confirm the already formed opinion that not enough is being done to treat pain syndromes, especially severe ones. It is necessary to improve the quality of care for patients suffering from chronic pain. In Europe, general practitioners occupy a large place in a comprehensive solution to this problem, to which about 70% of patients turn, as well as orthopedists, neuropathologists and rheumatologists.
Methods of treating chronic pain
The principles and methods of treating chronic pain associated with various diseases have much in common. Curation of pain is primarily aimed at determining the underlying disease that causes its occurrence, i.e. on finding out the cause of pain. To select an adequate analgesic therapy, it is necessary to assess the patient’s condition and measure the intensity of pain over time. It is important to determine the real goal of treatment and discuss it with the patient. In most cases, the goal is to reduce the intensity of pain (as far as possible) and its duration, functional abilities of the patient and improve the patient’s adaptation to everyday life.
In the fight against non-cancer (“non-cancerous”) or non-oncological pain, the principles of pain treatment are partly borrowed from the experience of oncologists (for example, WHO’s “analgesic ladder”), but for many reasons they cannot simply be transferred to rheumatological practice. Thus, in patients with a rheumatological profile, a decrease in the intensity of pain is impossible without pathogenetic antirheumatic therapy, which suppresses chronic autoimmune inflammation, which is the basis of the damaging processes that cause pain. Therefore, among the methods of treating chronic pain syndrome in rheumatology patients, systemic pharmacotherapy, including the so-called disease-modifying and “basic” drugs, corticosteroids, chondroprotectors, etc., is in the first place.
The effect of systemic pharmacotherapy is well complemented by local effects (intra-articular administration of drugs, the imposition of ointments and gels, transdermal therapeutic systems), as well as physiotherapeutic methods. But sometimes it takes many months before it is possible to suppress the activity of the underlying disease, and in this long period the patient has to deal with chronic pain. Pathogenetic therapy, even with high efficiency, does not always sufficiently suppress the clinical manifestations of the disease and, in particular, pain. This is especially true for long-term sick people, in whom the long-term pathological process in the joints is accompanied by the development of irreversible destructive changes leading to the “decompensation” of the function of the joints. The development of irreversible structural changes in the joints is naturally associated with an increase in pain, which often reaches considerable intensity. In such situations, it is necessary to increase precisely the analgesic effects and, often, the connection of drugs with a mandatory analgesic effect. In the later stages of rheumatic diseases, analgesics, as well as in oncology, are essentially palliative care and are used according to the “analgesics ladder”, when the increase in pain intensity is the basis for the sequential (stepwise) use of more and more powerful analgesics.
Study of chronic pain in Europe
As shown above cited a study of chronic pain in Europe, nonsteroidal anti-inflammatory drugs — NSAIDs (44% of patients), paracetamol (23%) and weak opioids (18%) are most often prescribed to patients for pain relief. Paracetamol is considered a first-stage drug and is prescribed for mild and moderate pain, not associated with inflammation. Paracetamol is a non-opioid analgesic of central action, apparently blocking cyclooxygenase (COX) in CNS structures. The lack of influence of paracetamol on the synthesis of prostaglandins in peripheral tissues explains the fact that it does not have a negative effect on the mucous membrane of the gastrointestinal tract (GIT) and water-salt metabolism (sodium and water retention). With more severe pain and inflammation, NSAIDs are prescribed, in particular Coxibs (second stage of the analgesic ladder). With severe pain and ineffectiveness of paracetamol and NSAIDs use opioids (third stage).
In the choice of medicine, modern doctors are guided by generally accepted clinical guidelines. For the treatment of osteoarthritis of large joints, the recommendations of the European League against rheumatism in 2000 were the most famous. According to these recommendations, along with paracetamol, NSAIDs, which were first-line drugs in Russia, were widely prescribed. Over the past few years, recommendations for the treatment of musculoskeletal pains have undergone significant changes. With the advent of selective COX-2 inhibitors (coxibs), which have less damaging potential for the gastrointestinal tract, these drugs have gained an advantage over NSAIDs in patients with medicinal gastropathy. In later recommendations, the emphasis shifted to Coxibs and non-selective NSAIDs as the basis of pharmacological therapy. After accumulating sufficient extensive experience in the use of coxibs and non-selective NSAIDs, it became obvious that with prolonged use these drugs can have a toxic effect not only on the gastrointestinal tract, but also on other internal organs such as the heart, kidneys, and liver. This was the basis for recommendations to limit the long-term use of drugs of this class. Thus, influential organizations in the United States (Food and Drug Administration) and Europe (European Medicines Agency) concluded that there was an undoubted increase in cardiovascular risk in patients taking NSAIDs, especially such a COX-2 inhibitor as rofecoxib, and strongly recommended limiting the use of all NSAIDs based on the principle of the lowest possible dose for the shortest possible period. General practitioners found themselves in a difficult position, since generally accepted recommendations in the light of new data actually expired, and new recommendations have not yet been proposed by official organizations. In this situation, doctors should find alternative options for analgesic therapy, replacing NSAIDs or combining their lower doses with other drugs.
Improving the effectiveness of treatment of acute and chronic pain is achieved by using a combination of painkillers with different but complementary mechanisms and temporal characteristics of the action. The main purpose of the combination of drugs is to achieve greater analgesic activity, compared with each of the drugs included in the combination. Increased analgesia is possible with smaller doses of each of the active ingredients, which potentially improves the tolerability and safety characteristics of the analgesics used. Most often, NSAIDs and paracetamol are combined with weak opioids. Combinations of paracetamol with opioids are recommended by WHO for the treatment of moderate to severe pain. In this regard, interest in opioid analgesics significantly increased, which, compared with NSAIDs, have significantly less organ-toxic effects. This interest is reflected in the latest recommendations of the European League against rheumatism (EULAR) for the treatment of hip joint osteoarthritis. Opioid analgesics are considered as a useful alternative to NSAIDs and coxibs in cases of intolerance, ineffectiveness or contraindications to their use (bronchial asthma, high risk of cardiovascular events, ulcers, bleeding or perforation of the intestines).
These recommendations are based on literature data and expert opinions, which indicate that opioids lack cardiovascular complications and have a negative effect on the kidneys and mucous membrane of the gastrointestinal tract, typical of NSAIDs. The Working Group on Pain Management (WGPM), which has been active for several years, proposed its algorithm for treating pain in osteoarthritis in patients with such risk factors as cardiovascular and gastrointestinal. According to the recommendations of WGPM, mild opioids are initially used for moderate and severe pain, and if they are ineffective, more active opioid analgesics are used (quoted in S.A. Schug, 2007 ).
Tramadol hydrochloride is a weak opioid that is not on the list of drugs. In recent years, it has become more widely used in the treatment of osteoarthritis, since it does not cause gastrointestinal problems, kidney complications and does not damage the articular cartilage.