Modified sharp method: Factors influencing reproducibility and variability*,**
Section snippets
Patients
Three hundred and seventy-six patients were monitored from 1985 at the outpatient clinic of the Department of Rheumatology at the University Hospital of Nijmegen. Only patients who met the American Rheumatism Association (ARA) classification criteria for rheumatoid arthritis with a disease duration of less than 1 year and who had not been treated with disease-modifying antirheumatic drugs (DMARDs) were included in the study. The follow-up period varied from 0 (only baseline) to 108 months.
I. Reproducibility: Interobserver variation study
Table 1 shows the Pearson correlation coefficients of the absolute Sharp scores between the 3 observers.The correlation coefficients between observers 1 and 2 vary between 0.82 and 0.94; the correlations with observer 3 are much lower—between 0.58 and 0.85.
II. Reproducibility: Interobserver variation, influence of follow-up time
There appears to be higher reproducibility when the follow-up time increases; after 3 years the correlation coefficients between observers 1 and 3 have almost significantly increased (z score = −1.70, P =.089) and those between observers 2
I. Reproducibility: Interobserver variation study
Interobserver variability of radiologic assessment is reasonably well documented. Tables 5 and 6 give an overview of studies in which interobserver variation has been calculated.
Table 5 summarizes the results of 9 studies on interobserver correlation coefficients. It includes only studies using the (modified) Sharp method, possibly with minimal methodologic deviations. In 6 of the studies 6, 8, 9, 10, 11, 12, the correlation coefficients between observers are very high, above 0.90. But in 3
Conclusions
This study demonstrates that interobserver and intraobserver variability, the time interval between readings, and the number of measurements within a given period considerably affect precision, sensitivity to change, and the validity of van der Heijde's modification of the Sharp method. Attention must be paid to these factors if radiographic scoring is to be applied in clinical research. The regular calibration of radiographic scoring (by the same observer and by various observers) seems
Acknowledgements
This study was supported by a grant from The Dutch Arthritis Association.
References (20)
- et al.
Effects of hydroxychloroquine and sulphasalazine on progression of joint damage in rheumatoid arthritis
The Lancet
(1989) Toward an understanding of patient outcome measurement
Arthritis Rheum
(1983)- et al.
Methods of scoring the progression of radiologic changes in rheumatoid arthritis
Arthritis Rheum
(1971) - et al.
How many joints in the hands and wrists should be included in a score of radiologic abnormalities used to assess rheumatoid arthritis?
Arthritis Rheum
(1985) - et al.
Standardized radiological evaluation of rheumatoid arthritis in therapeutic trials.
- et al.
A methodological framework for developing and selecting endpoints in clinical trials
J Rheumatol
(1982) - et al.
Combination of sulphasalazine and methotrexate versus the single components in early rheumatoid arthritis: a randomized, controlled, double-blind, 52 week clinical trial
Br J Rheumatol
(1997) - et al.
Measurement and prediction of radiological progression in early rheumatoid arthritis
J Rheumatol
(1994) - et al.
Prognostic factors for radiographic damage and physical disability in early rheumatoid arthritis. A prospective follow-up study of 147 patients
Br J Rheumatol
(1992) - et al.
Observer variation in quantitative assessment of rheumatoid arthritis. Part I. Scoring erosions and joint space narrowing
Invest Radiol
(1986)
Cited by (22)
Imaging as a follow-up tool in clinical trials and clinical practice
2008, Best Practice and Research: Clinical RheumatologyCitation Excerpt :Although the Sharp score may have an advantage over the Larsen score in early arthritis37, there is still no universally accepted technique, and modifications to the existing schemes are often proposed. Considerable interobserver variation must be taken into account, especially when dealing with multicentre trials, when applying any of these methods.38 Recently, methods have been proposed for fully automated measurement of joint space width in hand X-rays, automated erosion spotting, and visualization of pathological deviations from healthy bone texture caused by RA.39,40
Assessing damage in individual joints in rheumatoid arthritis: A new method based on the Larsen system
2004, Revue du Rhumatisme (Edition Francaise)Obesity associated with active, but preserved joints in rheumatoid arthritis: Results from our national registry
2016, Archives of Rheumatology
- *
Hilde L. Swinkels, MSc: Health Scientist, Department of Rheumatology, University Medical Centre I Nijmegen, The Netherlands; Roland F.J.M. Laan, MD, PhD: Department of Rheumatology, University Medical Centre Nijmegen, The Netherlands; Martin A. van 't Hof, PhD: Department of Medical Statistics, University Medical Centre Nijmegen, The Netherlands; Désirée M.F.M. van der Heijde, MD, PhD: Department of Rheumatology, University Hospital of Maastricht, The Netherlands; Niek de Vries, MD, PhD: Department of Rheumatology and Clinical Immunology, University Medical Centre Utrecht, The Netherlands; Piet L.C.M. van Riel, MD, PhD: Professor of Rheumatology, Department of Rheumatology, University Medical Centre Nijmegen, The Netherlands.
- **
Address reprints to Prof. Dr. Piet L.C.M. van Riel, Department of Rheumatology, University Medical Centre Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands. E-mail: [email protected]