P132 An exploration of the clinical and functional characteristics of a thumb base osteoarthritis cohort
Authors: Mbanasor Edward C , Arden Nigel K , Dean Ben J. F , Rombach Ines , Adams Jo 
Published: April 2020

Abstract

Background
Base-of-thumb osteoarthritis (BTOA) is common in older people and presents with significant levels of pain and disability. In the UK over four million people live with BTOA and this is likely to significantly increase with an increasingly elderly demographic. There is currently no consensus on the diagnostic criteria for BTOA. This study explored and reported the local signs and symptoms of BTOA in a patient cohort. Aims and objectives: to characterise the localised signs and symptoms; identify which factors contribute to differences in pain, function and quality of life outcomes in patients treated for BTOA; determine whether there is any association between hand impairment and hand function.

Methods
An exploratory secondary analysis of Osteoarthritis of the Thumb Therapy Trial II (OTTER II) participants was conducted. This was a cohort of patients with BTOA in an out-patient setting. Data analysed included clinician- and patient-reported outcomes using a combination of standardised and non-standardised questionnaires to capture impairment and functional outcomes. Cohort characteristics were summarised and described using appropriate descriptive and exploratory analysis. The independent t-test and Pearson’s correlation coefficient were used to report statistical significance and associations.

Results
Baseline data from 349 patients (mean age of 62.7 years, 78.5% females) were analysed. The most prevalent signs and symptoms (≥ 75% of cohort) were hand pain that worsens on span grip (87.4%), hard tissue enlargement of the carpometacarpal joint (76.8%) and positive thumb adduction provocation test (75.6%). Signs and symptoms presentation were most severe for females and there was notable gender-age group variation. Females presented with significantly worse disability in recreational activity performance (DASH component score - median: 3 vs 2; P &lt; 0.001) and those aged over 65 presented with significantly worse pain outcomes. Right-hand dominant males had significantly worse pain and function. A moderate-positive association was found between AUSCAN Hand Pain Total Score and AUSCAN Hand Function Total Score (r = 0.66, P = &lt;0.001).
This analysis identified and reported for the first time the most prevalent signs and symptoms and differences in their presentations (gender and age group) in a large cohort of BTOA patients. These data can contribute to defining robust and evidence-based diagnostic criteria. These data can assist in identifying patients with BTOA who experience worse pain, function and quality of life outcomes.

Conclusion
This study has identified the pertinent signs and symptoms and clinically relevant patient characteristics and associations. This could assist clinicians in accurately identifying patients for early intervention and contribute to the development of efficient, effective and personalised management strategies and improve BTOA prognosis.

Disclosures
E.C. Mbanasor None. N.K. Arden None. B.J.F. Dean None. I. Rombach None. J. Adams None.