Factors associated with impaired physical function in elderly rheumatoid arthritis patients who had achieved low disease activity.

Objectives: We aimed to investigate factors associated with impaired physical function [defined as Health Assessment Questionnaire Disability Index (HAQ-DI) >0.5] of old-old (aged 75-84 years) patients with rheumatoid arthritis.

Methods: Data from 15,185 rheumatoid arthritis patients in the National Database of Rheumatic Disease in Japan were extracted from 2017 to 2018. We enrolled 3708 patients aged 55-84 years in Simplified Disease Activity Index (SDAI) ≤11 and Steinbrocker Stage I/II. Factors associated with HAQ-DI >0.5 were analysed by multivariable logistic regression.

Results: About half of the old-old patients received methotrexate, which was lower than middle-aged (55-64 years) and young-old patients (65-74 years). The proportion of glucocorticoids in the old-old patients was highest among the three groups, and biological disease-modifying antirheumatic drugs were similarly used. The prevalence of HAQ-DI >0.5 was significantly higher in old-old patients with low disease activity than in those with remission. The same was true in the middle-aged and young-old patients. Multivariable analysis showed age, higher SDAI, glucocorticoid use, and methotrexate nonuse were significantly associated with HAQ-DI >0.5 in the old-old patients.

Conclusions: Achieving SDAI remission was an ideal goal for old-old patients in terms of physical function. Glucocorticoids and a low proportion of methotrexate use may influence the physical function of old-old patients.