Validation and Reliability of the Vietnamese Pain Self-Efficacy Questionnaire in Knee Osteoarthritis

Inclusion criteria

Participants will be eligible for inclusion if they meet all of the following conditions:

• Age ≥ 50 years.
• Diagnosis of knee osteoarthritis (OA) according to the criteria of the American College of Rheumatology (ACR), confirmed by:

• application of ACR criteria by the investigator at the time of enrollment; or
• a prior diagnosis documented in medical records by a rheumatologist or musculoskeletal specialist.
• Presence of chronic pain related to knee OA, with current pain intensity ≥ 1 on the Visual Analog Scale (VAS).
• No acute flare of knee pain within the past 2 weeks.
• Ability to perform activities of daily living (with or without assistance).
• Ability to read, understand, and complete questionnaires in Vietnamese.
• Willingness to participate and provide informed consent.

Exclusion criteria

Participants will be excluded if they meet any of the following conditions:

• Diagnosis of severe psychiatric disorders (e.g., schizophrenia, severe anxiety disorders).
• Presence of cognitive impairment that interferes with the ability to comprehend or answer the questionnaire.
• Diagnosed with systemic inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus, or gout.
• Presence of other chronic pain conditions (unrelated to knee OA) that are predominant and significantly affect mobility and daily functioning.
• History of intra-articular injection or knee surgery within the past 3 months.
• Questionnaire (PSEQ) with ≥ 20% of items missing or invalid.