Have we been comparing apples to oranges when it comes to the minimum clinically important difference (MCID) measure? Indeed, clinicians need uniformity in order to determine whether a statistically detectable improvement in a postoperative patient-reported outcome measure (PROM) is likely big enough to be of value to a patient or to justify an intervention.
A group from Massachusetts General Hospital, Harvard Medical School, including co-author Daniel Tobert, M.D., set out to achieve some clarity on this issue. Their study, “What Is the Clinical Benefit of Common Orthopaedic Procedures as Assessed by the PROMIS Versus Other Validated Outcomes Tools?” was published in the September 1, 2022, edition of Clinical Orthopaedics and Related Research.
“PROMIS (Patient-reported Outcomes Measurement Information System) is a metric that is increasingly being used to track patient improvement and measure healthcare value,” stated Dr. Tobert to OTW. “However, as a relatively new metric, it is unclear what numerical change in PROMIS scores represents clinical improvement. This is important as clinical research uses this outcome as a way to determine the success of treatment.”
The study authors enrolled patients undergoing the following surgeries: total hip arthroplasty (THA) for osteoarthritis, total knee arthroplasty (TKA) for osteoarthritis, one-level posterior lumbar fusion for lumbar spinal stenosis or spondylolisthesis, anatomic total shoulder arthroplasty or reverse total shoulder arthroplasty for glenohumeral arthritis or rotator cuff arthropathy, arthroscopic anterior cruciate ligament reconstruction, arthroscopic partial meniscectomy, or arthroscopic rotator cuff repair.
A total of 9,925 patients completed preoperative PROMIS assessments, with 9,478 completing other preoperative outcomes tools (Hip Disability and Osteoarthritis Outcome Score, Knee Disability and Osteoarthritis Outcome Score, numerical rating scale for leg pain, numerical rating scale for back pain, and QuickDASH).
“This work is advantaged by using only primary procedures and procedures that are common in orthopaedic surgery,” explained Dr. Tobert. “The most important findings were that the minimum clinically important difference in PROMIS scores were relatively similar across different procedures.”
“Using THA as an example,” wrote the authors, “minimum clinically important difference attainment using PROMIS was achieved by 76% of patients using an anchor-based threshold of 7.9 points. However, 82% of THA patients attained minimum clinically important difference using the MDC 95 [95% confidence minimal detectable change] method (6.1 points), and 88% reached minimum clinically important difference using the 1/2 SD [standard deviation] method (3.9 points).”
“Using the Hip Disability and Osteoarthritis Outcome Score metric, 86% of THA patients reached the anchor-based minimum clinically important difference threshold (17.5 points). However, 91% of THA patients attained the minimum clinically important difference using the MDC 90 [90% confidence minimal detectable change]. method (12.5 points), and 93% reached minimum clinically important difference using the 1/2 SD [standard deviation] method (8.4 points).”
“In general, the proportion of patients reaching minimum clinically important difference was lower for PROMIS than for other validated outcomes tools; for example, with the 1/2 SD method, 72% of patients who underwent arthroscopic partial meniscectomy reached the minimum clinically important difference on PROMIS Physical Function compared with 86% on the Knee Disability and Osteoarthritis Outcome Score.”
Dr. Tobert indicated to OTW, “These results set benchmarks for PROMIS scores and will help healthcare systems measure improvement initiatives. Additionally, the MCID thresholds can be used in future clinical research efforts.”
