DAS28-ESR may underestimate disease activity in rheumatoid arthritis patients with nonalcoholic fatty liver disease:...

Although approximately one-third of patients with rheumatoid arthritis (RA) have comorbid nonalcoholic fatty liver disease (NAFLD), the clinical characteristics of these patients remain unclear. The aim of this study was to clarify the clinical characteristics of RA patients classified as having NAFLD based on imaging, with a focus on composite disease activity assessment.

This retrospective cohort study analysed data from 349 RA patients enrolled in the Nagahama Riumachi Cohort between March 2017 and August 2023. Patients with liver diseases other than NAFLD were excluded. NAFLD was classified based on findings from abdominal computed tomography and/or ultrasonography performed during the cohort period. Disease activity was assessed using the Clinical Disease Activity Index (CDAI), Simplified Disease Activity Index (SDAI), Disease Activity Score in 28 joints using C-reactive protein (DAS28-CRP), and Disease Activity Score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR). Functional status was evaluated using the Health Assessment Questionnaire Disability Index (HAQ-DI). Factors associated with NAFLD were examined by logistic regression, and repeated measurements during follow-up were analysed using linear mixed-effects models.

Seventy-three patients (20.9%) were classified as having NAFLD and 276 (79.1%) as not having NAFLD. Patients in the NAFLD group were younger, had a higher proportion of men, and had a higher prevalence of body mass index (BMI) ≥ 25 kg/m². There were no significant differences between the groups in disease activity assessed by CDAI, SDAI, or DAS28-CRP. However, the NAFLD group had significantly lower DAS28-ESR and erythrocyte sedimentation rate (ESR) values despite similar C-reactive protein (CRP) levels. HAQ-DI was lower in the NAFLD group, especially in the lower-limb domain. In multivariable analysis, younger age and higher (BMI) were independently associated with NAFLD, but ESR and HAQ-DI were not significantly associated. In linear mixed-effects models, NAFLD classification was not significantly associated with ESR, although ESR tended to be lower in the NAFLD group.

Among patients with RA classified as having NAFLD, DAS28-ESR may underestimate disease activity compared with CRP-based or clinical indices. In these patients, DAS28-CRP, CDAI, and SDAI may provide complementary information.