Minimal Clinically Important Difference After Triamcinolone Acetonide Injection for Knee Osteoarthritis

Area of Science:

• Orthopedics
• Rheumatology
• Pharmacology

Background:

• Knee osteoarthritis (OA) significantly impacts patient quality of life.
• Intra-articular corticosteroid injections, such as triamcinolone acetonide (TA), are common treatments for OA.
• Defining the minimal clinically important difference (MCID) is crucial for evaluating treatment efficacy.

Purpose of the Study:

• To define the MCID for TA injections in knee OA patients.
• To assess if MCID values change over a 6-month period.
• To determine the proportion of patients achieving MCID monthly post-injection.

Main Methods:

• Retrospective case series of 277 patients with knee OA receiving TA injections.
• Knee Injury and Osteoarthritis Outcome Score (KOOS) was administered pre-injection and monthly for 6 months.
• MCID was calculated as 0.5 standard deviations from preinjection KOOS scores.

Main Results:

• MCID values varied across KOOS subscales (7.98-12.35).
• The proportion of patients achieving MCID for pain ranged from 36.2% to 50.5% across the 6-month follow-up.
• Patients not achieving MCID for pain by 1 month had a 2.19 times higher odds of receiving a repeat injection within 6 months.

Conclusions:

• Distribution-based MCID values for KOOS subscales in knee OA patients receiving TA injections were established.
• Significant pain improvement is expected within the first month, with diminishing effects over time.
• Lack of early pain improvement is a predictor for repeat injections, highlighting the importance of follow-up assessments.