Related Experiment Video
Updated: Apr 11, 2026
Preliminary Study on Acupuncture Combined with Grain-sized Moxibustion for Treating Rheumatoid Arthritis with Finger Joint Pain
Published on: May 16, 2025
Minimal Clinically Important Difference as Applied in Rheumatology: An OMERACT Rasch Working Group Systematic Review
Beyza Doganay Erdogan1, Ying Ying Leung2, Christoph Pohl2
1From the Ankara University Faculty of Medicine, Department of Biostatistics, Ankara, Turkey; Department of Rheumatology and Immunology, Singapore General Hospital, Singapore; Duke-NUS Graduate Medical School, Singapore; Department of Internal Medicine II, Rheumatology, Clinical Immunology, Osteology, Physical Therapy, and Sports Medicine, Schlosspark-Klinik, Teaching Hospital of the Charité, University Medicine Berlin, Berlin, Germany; Swiss Paraplegic Research, Nottwil, Switzerland; Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and UK National Institute for Health Research Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.B. Doganay Erdogan, PhD, Assistant Professor, Ankara University Faculty of Medicine, Department of Biostatistics; Y.Y. Leung, MD, Assistant Professor, Duke-NUS Graduate Medical School, Singapore; C. Pohl, MD, Department of Internal Medicine II, Rheumatology, Clinical Immunology, Osteology, Physical Therapy and Sports Medicine, Schlosspark-Klinik, Teaching Hospital of the Charité, University Medicine Berlin; A. Tennant, PhD, MD, Scientific Adviser, Swiss Paraplegic Research; P.G. Conaghan, MBBS, PhD, FRACP, FRCP, Professor of Musculoskeletal Medicine, Leeds Institute of Rheumatic and Musculoskeletal Medicine. beyzadoganay@gmail.com.
Objective:
We aimed to evaluate how minimal (clinically) important differences (MCID/MID) were calculated in rheumatology in the past 2 decades and demonstrate how the calculation is compromised by the lack of interval scaling.
Methods:
We conducted a systematic literature review on articles reporting MCID calculation in osteoarthritis (OA) and rheumatoid arthritis (RA) from January 1, 1989, to May 9, 2014. We evaluated the methods of MCID calculation and recorded the ranges of MCID for common patient-reported outcome measures (PROM). Taking data from the Health Assessment Questionnaire (HAQ), we showed the effects of performing mathematical calculations on ordinal data.
Results:
A total of 330 abstracts were reviewed and 123 articles chosen for full text review. Thirty-six (19 OA, 16 RA and 1 OA-RA) articles were included in the final evaluation. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was the most frequently reported PROM with relevant calculations in OA, and the HAQ in RA. Sixteen articles used anchor-based methods alone for calculation of MCID, and 1 article used distribution-based methods alone. Nineteen articles used both anchor and distribution-based methods. Only 1 article calculated MCID using an interval scale. Wide ranges in MCID for the WOMAC in OA and HAQ in RA were noted. Ordinal-based derivations of MCID are shown to understate true change at the margins, and overstate change in the mid-range of a scale.
Conclusion:
The anchor-based method is commonly used in the calculation of MCID. However, the lack of interval scaling is shown to compromise validity of MCID calculation.
Related Concept Videos
01:22Rheumatic Heart Disease II: Clinical Manifestations and Diagnostic Studies
01:21Rheumatic Heart Disease III: Medical Management
01:22Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence
01:23Rheumatic Heart Disease I: Introduction