Clinical diagnosis of osteoarthritis

Significant progress in understanding the pathophysiology and evolution of osteoarthritis has led not only to improved diagnostics of the disease, but also to a reassessment of the methodology and metrology of clinical studies in osteoarthritis. Clinical diagnostics of osteoarthritis is difficult. This is due to a number of factors:

• often asymptomatic disease,
• dissociation between radiological picture and clinical manifestation,
• frequent discrepancies between arthroscopy and radiography data of the affected joints,
• the lack of reliable biological markers of cartilage metabolism that reflect the progression of osteoarthritis and have prognostic value,
• individual assessment criteria for each localization of osteoarthritis (hands, knees, hip joints, etc.), but taken together they are not suitable for the generalized form of osteoarthritis.

Due to the emergence of new drugs for the treatment of osteoarthrosis on the pharmaceutical market and a large number of publications with the results of controlled studies, it became necessary to develop unified criteria for effectiveness. The list of indicators that could be included in the protocol of a clinical study of osteoarthrosis is quite large. These indicators can be conditionally divided into: subjective (indicators of pain, functional capacity, quality of life) and objective - characterizing the progression of the disease (according to X-ray, MRI, arthroscopy, ultrasound, radioisotope scanning; biological markers).

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Pain

Most often, the visual pain scale (Huskisson VAS) and the Likert scale are used to assess pain in patients with osteoarthritis. The results of numerous studies have demonstrated their high information content. The first is a vertical or horizontal line 10 cm long (0 cm - no pain, 10 cm - maximum pain), the second is the same line, on which "pain scores" from 0 (no pain) to 5 (maximum pain) are plotted. Variants of "classic" analog scales - chromatic analog scale and others - are rarely used in clinical studies of osteoarthritis. Since pain is a subjective symptom, its severity on the appropriate scale should be noted by the patient himself.

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Morning stiffness

Morning stiffness in patients with osteoarthritis is an inconstant symptom; compared to patients with rheumatoid arthritis, its duration is significantly shorter (no more than 30 min). Therefore, it is of less importance in assessing the status of a patient with osteoarthritis than, for example, joint pain. N. Bellamy and WW Buchanan (1986) asked patients with osteoarthritis to assess the importance of this symptom themselves. Most patients considered morning stiffness to be a moderately important symptom. Given the short duration of this symptom, it is advisable to assess its severity rather than duration (unlike rheumatoid arthritis). To facilitate assessment, analog scales have been adapted for the morning stiffness indicator.

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Time to travel 50 feet

This indicator is applicable only in the study of patients with osteoarthrosis of the joints of the lower extremities. The results of the study conducted by N. Bellamy and WW. Buchanan (1984) showed that even in patients with gonarthrosis and coxarthrosis this indicator is of little information, therefore the use of the 50-foot walking time indicator in clinical studies of patients with osteoarthrosis is questionable.

Time to climb stairs

Similar to the previous one, the stair climbing time indicator is applicable only in case of lower limb joint damage. There are no standards defined for it (for example, the required number of steps). In addition, a number of concomitant diseases ( cardiovascular diseases, diseases of the nervous system ) can significantly affect the performance of this test. Thus, using the stair climbing time indicator in osteoarthritis is also inappropriate.

Determining the range of motion

Determination of the range of motion in patients with osteoarthritis is applicable only to the knee joint. Limited range of motion in the knee joint may reflect not only changes in the articular cartilage, but also in the joint capsule, periarticular muscles, and ligamentous apparatus. When the limb is bent at the knee joint, the relative position of the axes of the femur and tibia changes in such a way that a standard mechanical goniometer will not be able to measure the angle correctly. However, a properly trained specialist can correctly measure the flexion and extension angles in the knee joint, in which case this test can be included in the study protocol. It should be noted that clinical studies have found a statistically significant difference in the range of motion in the knee joint between patients receiving active treatment (NSAIDs) and placebo.

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Distance between ankles

Distance between ankles with maximum abduction of lower limbs. This test, which characterizes the range of adduction in the hip joint, can be quite informative if performed by a skilled specialist. Its informativeness has been demonstrated in studies of the effectiveness of NSAIDs in patients with coxarthrosis. However, like other indicators of joint geometry, this test is not recommended for use in clinical studies.

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Distance between the medial condyles of the femurs

The distance between the medial condyles of the femurs with maximum abduction of the lower limbs is a multifaceted test characterizing the volumes of adduction and external rotation in the hip joints and the volume of flexion in the knee joints. It can be informative only if performed by a trained specialist. Similar to the previous one, the informativeness of this indicator was demonstrated in a clinical study of the use of NSAIDs in osteoarthrosis. The need to include this test in the study protocol is questionable.

Doyle Index

The Doyle index is an adapted Ritchie index developed specifically for rheumatoid arthritis and osteoarthrosis. The test methodology includes an assessment of the sensitivity of joints on palpation, during movements, and an assessment of joint swelling using a point system. For unknown reasons, it did not arouse interest among rheumatologists; no one has determined its informativeness. It is possible that after additional studies, the Doyle index will be recommended for inclusion in the protocol of clinical trials of patients with generalized osteoarthrosis.

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Evaluation of joint swelling

Evaluation of joint swelling seems controversial, since in patients with osteoarthritis it can be caused not only by soft tissue swelling, but also by bone growth. In the first case, dynamics of the corresponding indicators can be expected against the background of treatment, in the second - no. Despite the fact that measuring the joint circumference in centimeters was included in the protocol of several studies, the informativeness of this test is limited and depends on the level of training of the researcher. Measuring the circumference is applicable only to the knee joints and joints of the hands. In the first case, a standard centimeter tape can be used, in the second - special plastic or wooden rings of different sizes. Even in clinical studies, in which the experience of using this test is much greater, it is rarely included in the research protocol.

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Assessment of wrist strength

Assessment of wrist strength using a pneumatic dynamometer is rarely included in osteoarthrosis research protocols, probably because these studies rarely focus on hand osteoarthrosis. This test should certainly be performed by a trained investigator. By pinching the dynamometer with the first and second fingers, the first carpometacarpal joint of the hand of a patient with osteoarthrosis can be assessed separately. The difficulty in interpreting the dynamics of the wrist strength indicator reduces the value of the test for clinical research.

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Consumption of analgesics

When assessing the effectiveness of symptomatic drugs used in the treatment of osteoarthritis, the main criterion is joint pain. In such cases, an indicator of analgesic intake is used for additional assessment of the dynamics of the pain syndrome. Paracetamol is usually used for this. Along with the drug under study, the patient is recommended to take paracetamol if necessary during the study with the mandatory completion of a specially designed diary. For additional assessment of the effect on pain of drugs that are not symptomatic (for example, chondroprotectors), NSAIDs can be used instead of paracetamol with subsequent recalculation of the dose taken to the equivalent of diclofenac. Given the higher incidence of side effects when prescribing NSAIDs, preference should still be given to paracetamol. To objectify the accounting of painkillers, special containers with a microchip placed in the lid are being developed, which records the number of times the container is opened.

Doses of NSAIDs equivalent to 150 mg diclofenac (Recommendations of the French Ministry of Health for conducting clinical trials in osteoarthritis

NSAIDs	Dose equivalent to 150 mg diclofenac, mg
Naproxen	1100
Ibuprofen	2400
Indomethacin	100
Flurbiprofen	300
Ketoprofen	300
Piroxicam	20

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Overall rating

This method can be used to evaluate:

• treatment effectiveness,
• tolerability of treatment,
• the functional capacity of the patient,
• severity of pain syndrome.

The first three points are assessed independently by the doctor and the patient, the last one - only by the patient. Usually the overall assessment is carried out using a point system.

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Health assessment

Methods for assessing the health of patients with osteoarthritis can be divided into specific and generic. This division is somewhat artificial, but it allows us to differentiate between methods used for all joints simultaneously (specific) and for individual joint groups (generic).

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WOMAC Index (Western Ontario and McMaster Universities osteoarthritis Index)

The WOMAC test is a questionnaire for self-completion by the patient, consists of 24 questions characterizing the severity of pain (5 questions), stiffness (2 questions) and functional ability (17 questions) of patients with gonarthrosis and coxarthrosis. It takes 5-7 minutes to complete the WOMAC questionnaire. The WOMAC index is a highly informative indicator that can be used to assess the effectiveness of drug and non-drug (surgical, physiotherapeutic) treatment.

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Algofunctional indices (AFI) of Lequesne

M. Lequesne developed two AFI - for osteoarthrosis of the knee and hip joints. Lequesne tests are also questionnaires for self-completion by the patient, the questions are divided into three groups - pain or discomfort, maximum walking distance and daily activity. The question concerning the patient's sexual sphere, which was included by the author in the questionnaire for coxarthrosis, is not required for studying the effectiveness of antirheumatic drugs. Lequesne indices were recommended by EULAR as an efficiency criterion for conducting clinical trials in patients with osteoarthrosis (WHO, 1985), and along with the WOMAC index - for assessing the efficiency of the so-called slow-acting drugs (SADOA). Statistically, the informativeness and reliability of the WOMAC and Lequesne indices are the same.

Dreiser's Algofunktional Index

The Dreiser Algofunctional Index was developed specifically for clinical studies of hand joint osteoarthritis and is a ten-item questionnaire. Nine out of ten questions concern the function of the hand joints, and the tenth (how willingly the patient responds to a handshake) rather reflects the severity of the pain syndrome. The Dreiser Index is a relatively new and little-studied test, so until its informativeness and reliability are determined, it is better not to include it in the study protocol.

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Health Assessment Questionnaire

The Health Assessment Questionnaire (HAQ) was developed at Stanford University by JF Fries et al. (1980), which is why it also has a second name - the Stanford Questionnaire. The questionnaire is easy to use and can be filled out by the patient within 5-8 minutes without the intervention of a doctor. The questions in the questionnaire are divided into 2 categories: self-care (dressing, getting out of bed, personal hygiene, etc.) and movement. The questionnaire is informative and reliable, it is recommended to use it to assess the health of a patient with generalized osteoarthritis.

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AIMS

AIMS (Arthritis Impact Measurement Scale) was developed by RF Meenan et al. (1980). 46 questions of the AIMS questionnaire are divided into 9 categories - mobility, physical activity, dexterity, social role, social activity, daily life, pain, depression, anxiety. G. Griffiths et al. conducted a comparative study of the WOMAC, HAQ and AIMS questionnaires and found some advantage of the first. The authors recommend using the WOMAC questionnaire in studies of knee and/or hip OA, and the HAQ and AIMS questionnaires - in studies of generalized osteoarthritis.

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FSI

FSI (Functional Status Index) was developed by A.M. Jette, O.L. Deniston (1978) as part of the Pilot Geriatric Arthritis Project. There are two versions of FSI: the "classic" version, consisting of 45 questions classified into three categories (dependence, pain, daily activities), which takes 60-90 minutes to complete, and the shortened (revised) version, consisting of 18 questions grouped into 5 groups (general mobility, hand mobility, self-care, housework, interpersonal contacts), which takes 20-30 minutes to complete. A special feature of FSI is the mandatory participation of the interviewer (doctor, researcher) when filling out the questionnaire. FSI can be used in clinical trials in patients with generalized osteoarthritis, although preference should still be given to HAQ and AIMS.

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Methods for assessing quality of life

Several methods for assessing quality of life have been developed to date. Four of them can be used in clinical studies of patients with osteoarthritis: the Short Form-36 (SF-36) Health Status Questionnaire, EuroQol, Health Utilities Index, and Nottingham Health Profile.

The Short Form-36 (SF-36) Health Status Questionnaire consists of 36 questions to be completed by the patient in 5 minutes. The SF-36 and the EuroQol questionnaire below are designed so that they can be completed by an interviewer over the telephone or sent to patients by mail.

EuroQol (European Quality of Life Questionnaire) consists of two parts - the questionnaire itself with 5 questions and the VAS, on which the patient evaluates his health.

The Health Utilities Index questionnaire was developed specifically for patients with malignant tumors. The questionnaire questions cover 8 features: vision, hearing, speech, mobility, dexterity, cognitive ability, pain and discomfort, emotions. This questionnaire is very rarely used to assess the quality of life of patients with a rheumatic profile. Usually, preference is given to the SF-36, less often to the EuroQol.

The Nottingham Health Profile questionnaire includes 38 items divided into 6 sections: mobility, pain, sleep, social isolation, emotional reactions, activity level. The patient can also fill out this questionnaire independently. Like the previous questionnaire, the Nottingham Health Profile is extremely rarely used in rheumatology.

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Visualization methods

To date, chondroprotective properties, defined as "...the ability to slow down, stop or reverse the degenerative process in hyaline cartilage in patients with osteoarthrosis", have not been proven for any medicinal substance. This is largely due to the fact that the question of the method for identifying the phenomenon of chondroprotection and the possibilities of radiography or alternative methods (arthroscopy, MRI) in this regard has not yet been widely discussed.

X-ray

In recent years, a large number of publications have appeared on radiography of joints affected by osteoarthrosis. Shooting techniques have been improved, many quantitative (measuring the width of the joint space) and semi-quantitative (assessment in points, degrees) methods for assessing radiographs in patients with osteoarthrosis have appeared. When conducting large controlled studies, radiography is the most preferred visualization method, which can indirectly characterize the dynamics of morphological changes in the tissues of a joint affected by osteoarthrosis.

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MRI

The use of MRI in controlled studies of osteoarthrosis is limited by its high cost and low availability. Moreover, there is evidence of only partial concordance of articular cartilage damage detected by MRI and arthroscopy. L. Pilch et al. (1994) found errors in the computer software used for volumetric studies of articular cartilage in osteoarthrosis. Thus, further study of the capabilities of MRI in clinical studies of patients with osteoarthrosis is necessary.

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Scintigraphy

P. Dieppe et al. (1993) confirmed the ability of scintigraphy to predict joint space narrowing in osteoarthrosis. However, its role in assessing the dynamics of morphological changes in the tissues of affected joints during clinical studies remains questionable.

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Ultrasound

SL Myers et al. (1995) demonstrated in vitro that high-frequency ultrasound provides accurate measurement of human articular cartilage thickness and produces an accurate image of its surface. In addition, ultrasound is a fairly accessible method that does not involve radiation exposure. However, the ability to determine the chondroprotective properties of drugs using ultrasound has not been proven. Further study of the capabilities of ultrasound in this area is required.

Arthroscopy

Arthroscopy provides the most reliable information about the condition of articular cartilage and tissues of the joint cavity. A large number of chondroscopy assessment systems have been developed. Despite this, the high invasiveness of the method sharply limits its use in clinical studies.

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