A randomized, double blind, placebo-controlled single-center study was designed to assess the efficacy and safety of Hyal-Joint® (active test product, AP) compared to placebo for pain relief and improvement of quality of life in adult subjects with osteoarthritis of the knee. The active test product is a dietary ingredient that consists of an extract of chicken combs containing HA (60–70%) and hydrolyzed proteins mostly collagen and other polysaccharides. The duration of the study was 8 weeks. The study took place from June 2005 to April 2006 in the United States and involved the participation of a single clinical service organization center (Miami Research Associates). The study protocol was approved by the IntegReview Ethical Review Board (Austin, Texas), and was conducted in accordance with the principles of the Declaration of Helsinki and its amendments. Written informed consent was obtained from all participants prior to enrollment in the study.
Male and female subjects of any race, aged 40 years or over, with symptomatic osteoarthritis of the knee were eligible provided that subjects experienced pain for at least 15 of the 30 days prior to the start of the study, symptoms had been present for at least 6 months, and a confirmatory X-ray diagnosis (Kellgren/Lawrence score ≥ 2) within the previous 6 months was available. Exclusion criteria were: known allergy to chicken (sodium hyaluronate is derived from chicken combs), corn, potato, rice or cellulose (derived from wood pulp); any inflammatory arthritic condition; multiple sclerosis or autoimmune disorder; treatment with oral corticosteroids within 4 weeks before screening; intra-articular corticosteroids in the target joint within 3 months before screening; significant injury to the target joint within the past 12 months; presence of any clinically significant medical condition judged by the investigator to preclude the patient's inclusion in the study; renal dysfunction (serum creatinine concentration > 1.5 times the upper limit of normal); liver dysfunction (serum alkaline phosphatase and aminotransferases > 2 times the upper limit of normal); and participation in a clinical study in the previous 30 days. Pregnant women, nursing mothers, or women of childbearing potential not using adequate methods of contraception were also excluded. A urine pregnancy test was performed before enrollment. New onset use of glucosamine, chondroitin sulfate, methylsulfonylmethane, or milk protein-based dietary supplements was not allowed. Subjects using these dietary products and willing to continue had to maintain stable doses within 3 months before screening and throughout the course of the study.
Treatment and patient evaluation
Study participants attended a screening visit (visit 1), which included medical history, physical examination, laboratory tests, radiographic confirmation of Kellgren/Lawrence score ≥ 2, assessment of the use of concomitant medication and/or dietary supplements, urine pregnancy test (when applicable), and first signing the informed consent. Subjects were instructed to discontinue or taper off gradually any treatment with NSAIDs, cyclooxygenase-2 inhibitors, or analgesics with the exception of acetaminophen, to ensure a minimum 3-day drug-washout period and were scheduled to return to the study center in 7 days for the baseline/randomization visit.
All eligible participants were sequentially assigned to one of the two masked products according to a predetermined computer-generated randomization schedule. Subjects were randomized (1:1) to Hyal-Joint® (Bioibérica, Barcelona, Spain), 80 mg, or matched placebo capsules. Subjects were instructed to take one capsule a day, in the morning immediately after breakfast. The study product was dispensed to subjects at each visit to cover the period of time until the next visit. On the other hand, patients were instructed to take rescue medication (paracetamol 500 mg) as needed with no more than four tablets (Tylenol) per day. The use of rescue medication was assessed by the pill return (pill count) method at each visit.
Assessments were performed at baseline (visit 2) and at 4 weeks (visit 3) and 8 weeks (visit 4) after initiation of the treatment. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC 3.0 Index) and the Short Form-36 (SF-36v2, Acute US Version 2.0) questionnaires were administered at each visit. The WOMAC is a disease-specific, self-administered questionnaire that evaluates three dimensions: pain, stiffness, and physical function with 5, 2, and 17 questions, respectively. Each question is rated on an ordinal scale of zero to four, with lower scores indicating minimal symptoms or physical disability. The three subscales can be scored separately or as a composite measure (aggregated total symptoms). The SF-36v2 is a multi-purpose, short-form health survey with 36 questions. The SF-36v2 yields an 8-scale profile of functional health and well-being scores as well as psychometrically-based physical and mental health summary measures and a preference-based health utility index. The SF-36v2 yields information on physical health (comprised of physical functioning, role-physical, bodily pain, and general health) and mental health (comprised of vitality, social functioning, role-emotional, and mental health). Finally, the physical (PCS-36) and the mental (MCS-36) component summaries can be calculated.
Efficacy and safety parameters
The primary efficacy variable was the comparative difference between the AP and the placebo arms in scores of the pain subscale of WOMAC and bodily pain of SF-36v2 at week 8. Secondary efficacy variables included the comparative difference between AP and placebo groups for all other WOMAC and SF-36v2 subscales, and the change over 8 weeks compared with baseline for the WOMAC and SF-36v2 subscales recorded in each study group.
At the end of the study (at 8 weeks), a subjective acceptance questionnaire was administered to determine the overall acceptability of the study products ("Do you believe the product you were taken during the study decreased your joint pain?" yes/no; "Do you believe the product you were taken during this clinical trial decreased any muscle aches that you experience?" yes/no). In addition, subjects were asked "Do you think you were taking the active product or placebo?".
Tolerability and safety parameters were the incidence and severity of adverse events reported throughout the study as well as changes in blood pressure, heart rate, and laboratory tests including complete blood cell count and biochemical profile. Treatment compliance was also recorded. Non-compliance was defined as taking less than 80% of the prescribed course of the study product. Use of rescue medication (paracetamol 500 mg) during the study period was also checked.
A sample size of 20 subjects (10 per group) provided 80% power at the alpha level of 0.05 to detect a mean change over time that is about equal to the within-group standard deviations for the change over time in score points for WOMAC and SF-36v2 endpoints, which were estimated from previous studies in subjects with osteoarthritis conducted at the clinical service organization center.
All randomized subjects were included in the intent-to-treat population. The ITT population was defined as all subjects who received the product and who had some follow-up evaluation. It includes subjects who dropped out of the study, were removed or lost to follow-up, or were seriously non-compliant with the regimen specified in the protocol. The efficacy (per-protocol) population consisted of subjects who completed all visits, and who were suitably compliant with the prescribed regimen (supplement or placebo), with an overall compliance rate between 80% and 120% inclusive. Last observation carried forward (LOCF) imputation method was performed for missing efficacy variables in the intent-to-treat and per-protocol analyses (PP). The safety population included all subjects who were randomized and received at least one dose of study product and for whom any safety follow-up evaluation (physical examination, laboratory tests, adverse events, subjective comments) were obtained.
Baseline characteristics in the two study groups were compared with the Student's t test of the Mann-Whitney U test for continuous variables, and with the chi-square (χ2) test or the Fisher's exact test for categorical variables. Changes over time from baseline to each subsequent visit within each study group were assessed for significance by the paired Student's t test or the non-parametric Wilcoxon signed-rank test. Statistical significance was set at P < 0.05.