Inter- and Intra-Observer Reliability of Modified Rodnan
Skin Score Assessment in Thai Systemic Sclerosis Patients:
A Validation for Multicenter Scleroderma Cohort Study
Chingching Foocharoen MD*1, Bandit Thinkhamrop PhD*2, Ajanee Mahakkanukrauh MD*1,
Siraphop Suwannaroj MD*1, Sittichai Netwijitpan MD*1, Kwanleutai Sripavatakul MD*3,
Wiriya Chuealee MD*4, Bodin Boottam MD*5, Patapong Towiwat MD*5, Patcharawan Seubmee MD*6,
Kittikorn Daungkum MD*7, Darunee Kongpan MD*3, Jintara Mangkala MD*8, Ratanavadee Nanagara MD*1
Affiliation :
*1 Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
*2 Department of Biostatistics and Demography, Faculty of Public Health, Khon Kaen University, Khon Kaen, Thailand
*3 Department of Medicine, Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand
*4 Department of Medicine, Sapphasitthiprasong Hospital, Ubon Ratchathani, Thailand
*5 Department of Medicine, Faculty of Medicine, Naresuan University, Phitsanulok, Thailand
*6 Department of Medicine, Roi Et Hospital, Roi Et, Thailand
*7 Department of Medicine, Khon Kaen Hospital, Khon Kaen, Thailand
*8 Department of Medicine, Nong Khai Hospital, Nong Khai, Thailand
Background : Assessment of the severity of skin tightness by the modified Rodnan skin score (mRSS) for systemic sclerosis
(SSc) has been found feasible, valid, and reliable. Despite being a major clinical outcome, it has not yet been validated by
Scleroderma Research Group.
Objective : To (a) determine the inter-observer variability vis-à-vis mRSS assessment by members of the Scleroderma Research
Group before and after mRSS-assessment training by an experienced rheumatologist and (b) determine intra-observer
variability.
Material and Method: Between June and August 2013, we conducted a descriptive study of Thai adult SSc patients and all
rheumatologists in the Scleroderma Research Group at Srinagarind Hospital, Khon Kaen University, Northeast Thailand.
Eleven rheumatologists assessed the mRSS of 22 SSc patients three times (i.e., before and after training, and eight weeks
after training). The intra-class correlation coefficient (ICC) and its 95% CI were estimated at week 8 after training.
Results : The mean and standard deviation (SD) of mRSS for inter-observer variability analysis was slightly decreased from
before training, after training (by an experienced rheumatologist), and at week 8 after training (17.311.9, 16.511.1, and
16.210.3, respectively). Intra-observer variability had moderate agreement before training (ICC 0.59; 95% CI 0.38-0.78),
which increased to good agreement after training and at week 8 after training (ICC 0.60; 95% CI 0.42-0.76 vs. 0.68;
95% CI 0.53-0.82, respectively).
Conclusion : Inter-observer variability for mRSS assessment decreased after training and the reduction persisted for eight
weeks after training. The ICC rose from moderate agreement at baseline to good agreement at the end of the study. The
mRSS assessment by members of the Scleroderma Research Group was reliable.
Keywords : Systemic sclerosis, Scleroderma, Modified Rodnan skin score, Validation, Inter-observer variability, Intra-observer
variability
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