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Exploring Dimensions of Stiffness in Rheumatoid and Psoriatic Arthritis: The ARAD and OMERACT Stiffness Special Interest Group collaboration


Sinnathura P1, Bartlett SJ1, Halls S1, Hewlett S1, Orbai AM1, Buchbinder R1, Henderson L1, Hill CL1, Lassere M1, March L1. J Rheumatol. 2019 Apr 1. pii: jrheum.181251. doi: 10.3899/jrheum.181251. [Epub ahead of print]

Author Information

1 From the Institute of Bone and Joint Research, Kolling Institute, St Leonards, NSW Australia; Rheumatology Department, Royal North Shore Hospital, St Leonards, NSW Australia; Sydney Medical School, University of Sydney, Sydney, NSW Australia; Divisions of Clinical Epidemiology, Rheumatology, and Respiratory Epidemiology, McGill University, Montreal Canada; Division of Rheumatology, Johns Hopkins Medicine, Baltimore USA; Department of Nursing and Midwifery, University of the West of the England, Bristol, United Kingdom; Monash Department of Clinical Epidemiology, Cabrini Institute, Melbourne, Victoria, Australia; Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Rheumatology Unit, The Queen Elizabeth Hospital, Adelaide, SA Australia; Discipline of Medicine, University of Adelaide, South Australia;1 School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW Australia; Rheumatology Department, St George Hospital, Kogarah, NSW Australia. The Australian Rheumatology Association Database is currently supported by unrestricted educational grants administered through the Australian Rheumatology Association from AbbVie Pty Ltd, Pfizer Australia, Sanofi Australia, Celgene Australian & NZ, Bristol-Myers Squibb Australia Pty Ltd. Previous sponsorship for ARAD included an Australian National Health and Medical Research Council (NHMRC) Enabling Grant [384330], Amgen Australia Pty Ltd, Aventis, AstraZeneca, Roche, Monash University, Cabrini Health. Infrastructure support for ARAD received from Cabrini Hospital, Royal North Shore Hospital and the Australian Rheumatology Association. P. Sinnathurai is supported by an NHMRC Postgraduate Scholarship. R. Buchbinder is funded by an NHMRC Senior Principal Research Fellowship. Address correspondence to Premarani Sinnathurai, Rheumatology Department, Royal North Shore Hospital, Reserve Road, St Leonards NSW 2125 AUSTRALIA.



It is not known how the experience of stiffness varies between diagnoses or how best to measure stiffness. The aims of this study were to: 1) compare stiffness in psoriatic arthritis (PsA) and rheumatoid arthritis (RA) using patient-reported outcomes, 2) explore how dimensions of stiffness are associated with each other and reflect the patient experience, 3) explore how different dimensions of stiffness are associated with physical function.


An online survey was sent to Australian Rheumatology Association Database participants (158 PsA, and 158 age- and sex-matched RA), assessing stiffness severity, duration, impact, importance, coping and physical function (mHAQ). Scores were compared between diagnoses and correlations among stiffness dimensions calculated. Multivariate regression was performed for stiffness severity, impact and duration on mHAQ, adjusting for age, sex, disease duration, obesity and pain. Cognitive debriefing was conducted via semi-structured telephone interviews.


Overall, 240/316 (75.9%) responded (124/158 RA (78.5%) and 116/158 (73.4%) PsA), with no significant difference in stiffness ratings between diagnoses. Scores for all stiffness dimensions were strongly correlated (r=0.52-0.89) and severity and impact were associated with mHAQ in both diagnoses. Stiffness duration was not associated with mHAQ in RA. In cognitive debriefing, participants described stiffness severity and impact by the effect on daily activities (10/16 and 14/16 participants respectively).


Stiffness ratings were similar between PsA and RA. Different dimensions of stiffness were strongly correlated. Stiffness severity and impact both independently predicted mHAQ. Stiffness was important to participants, however, measuring multiple dimensions of stiffness may have minimal additive value.