Effects of Intramuscular vs Intra-articular Glucocorticoid Injection on Pain Among Adults With Knee Osteoarthritis (Part 5)
In our last week’s article, we continued discussing the topics on “Patients” and on “Interventions Done” re the Effects of Intramuscular vs Intra-articular Glucocorticoid Injection on Pain Among Adults With Knee Osteoarthritis.
Let us now go to the topic on OUTCOMES. The study says that the researchers measured outcomes at baseline (the day of completing baseline assessments), and 2, 4, 8, 12, and 24 weeks after administration of the injection via digital or paper questionnaires.
Two of the researchers did the baseline Kellgren and Lawrence grade scoring blinded to the allocated treatment (interrater reliability: prevalence-adjusted κ value: 0.84; 95% CI, 0.75-0.93).
A consensus meeting was held for making final decisions for discrepant grades. The primary outcome was the severity of knee pain at 4 weeks measured with the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale (0-100; 0 indicates extreme pain).
The study further said that the Secondary outcomes included the KOOS pain score at 2, 8, 12, and 24 weeks; KOOS symptom, function, sport and recreation, and quality-of-life scores (0-100; 0 indicates extreme symptoms); Western Ontario and McMaster Universities Osteoarthritis Index pain, function, stiffness, and total scores (0-100; 0 indicates no pain); numeric rating scale of knee pain during the past week (0-10; 0indicates no pain); Intermittent and Constant Osteoarthritis Pain (0-100; 0 indicates no pain); and EuroQol with 5 dimensions and 5 response levels (−0.446 to 1.000; −0.446 indicates worst health related quality of life).
In addition, the researchers measured perceived recovery and the percentage of responders defined by the OMERACT-OARSI criteria.
Patients’ perceived recovery was measured with a 7-point Likert scale, and results were dichotomized into recovered (complete recovery, much improved, and slightly improved) or not recovered (no change, slightly worse, much worse, and worse than ever).
Talking of the Sample Size, the study was powered to test whether IM injection was non-inferior to IA injection regarding the KOOS pain score at 4 weeks’ follow-up. For this, the researchers used data from the trial of Henriksen et.al.for estimating an SD of 16 for the KOOS pain score.
It was said in the study that a sample size of 130 patients (65 per group) was needed to achieve 80% power at a significance level of α = .05 to detect noninferiority, assuming the true between group mean (SD) was 7 (16). Based on the reseachers’ prior experience in glucocorticoid injection trials, they expected a low rate of loss to follow-up of 5%.16,24. Therefore, they aimed to recruit 137 patients, the study said.