Symptom-modifying effects of oral avocado/soybean unsaponifiables in routine treatment of knee osteoarthritis in Poland. An open, prospective observational study of patients adherent to a 6-month treatment

Abstract

Objectives: Observational studies provide insights into real-life situations. Therefore, we assessed the effects of oral avocado/soybean unsaponifiable (ASU) capsules on pain relief and functional ability in patients, while they were receiving a routine treatment for knee osteoarthritis (OA).

Material and methods: An open, prospective, observational 6-month study was conducted in 99 centers in Poland in a group of 4822 patients with symptomatic knee OA receiving one 300 mg ASU capsule/day as a routine medication. The patients had no diagnoses of other rheumatic diseases and were not treated with other symptomatic slow-acting drugs for osteoarthritis (SYSADOAs). Data on OA symptoms and therapy were collected from the initiation of ASU treatment (visit 0) and during 3 consecutive control visits performed every 2 months (visits 1-3). Functional Lequesne index, severity of joint pain of one symptomatic knee (Laitinen index and VAS), use of analgesics and non-steroidal anti-inflammatory drugs (NSAIDs), adherence to treatment and adverse events were evaluated and recorded using electronic Case Report Forms.

Results: Four thousand one hundred and eighty-six patients (86.8%) attended all 4 visits. In 94.2% of patients (mean age 60.7 ±11.6 years SD, 73.4% female) at least one OA risk factor was identified. There was a significant improvement in functional ability between the last and baseline visits as evidenced by the median Lequesne index decreasing from 8 to 4 points (p < 0.001). Measures of pain intensity also fell significantly (p < 0.001) throughout the study: median Laitinen score decreased from 6 to 3 points, median pain at rest VAS - from 1.8 to 0 cm and median pain during walking VAS - from 5.6 to 1.9 cm. The significant differences were also noted between consecutive visits. The proportion of patients using analgesics and NSAIDs declined from 58.8% at the baseline visit to 24.9% at the last visit 3 (p < 0.001). Defined daily dose of NSAIDs decreased significantly from 1 at the baseline visit to 0.67 at the visit 3. Severe adverse events associated with ASU treatment were not observed.

Conclusions: It was the first observational study in Poland evaluating the effects of routine knee OA treatment with oral ASU. Only a small group of patients (13.2%) treated with ASU discontinued the study. The majority of patients adherent to the ASU treatment for 6 months showed gradual alleviation of joint pain, improvement in functional ability and a significant reduction in NSAIDs intake.

Keywords: NSAIDs-sparing effect; avocado/soybean unsaponifiables; osteoarthritis treatment.

Fig. 1

Assessment of pain at rest. The figure presents the significance of differences between median VAS values (Q1–Q3, min–max) at a given visit vs. visit 0 tested with Wilcoxon test (n = 4186).

Fig. 2

Pain at rest during ASU treatment measured with the VAS and with Laitinen scale in the subgroups of patients: A) VAS values in BMI subgroups, B) VAS values in the compliant and not fully compliant patients, C) Laintinen scale values in BMI subgroups, D) Laitinen scale values in the compliant and not fully compliant patients. Figures 2A and 2C present medians of pain assessment scores at consecutive visits in patients by BMI subgroups (2A VAS, 2C Laitinen scale). Figures 2B and 2D present medians of pain assessment scores at consecutive visits in the subgroups of compliant and not fully compliant patients (2B VAS, 2D Laitinen scale) (n = 4186).

Fig. 3

Functional impairment measured with the Lequesne index – overall assessment during ASU treatment (n = 4186)*. *Figure presents the significance of difference between medians of the Lequesne index values at a given visit vs. visit 0 tested with Wilcoxon test.

Fig. 4

Use of analgesics and NSAIDs – overall assessment. Figure 4A presents statistical significance of differences between proportions of patients using analgesics and NSAIDs at a given visit and at visit 0. Statistical analysis was performed with McNemar test. Figure 4B shows the use of NSAIDs in defined daily dosage (DDD) median values (only patients taking NSAIDs at a given visit). The significance of differences at a given visit vs. visit 0 were tested with Wilcoxon test