RESUMO
BACKGROUND: Rheumatoid Arthritis (RA) is a chronic inflammatory disease with high impact on patients´ quality of life (QoL). The Rheumatoid Arthritis Quality of Life Questionnaire (RAQoL) is a self-completed questionnaire designed to assess QoL in patients with RA. A Portuguese adaptation of the RAQoL was available but required formal validation. AIM: To validate the RAQoL into the Portuguese language. METHODS: Patients with diagnosis of RA were included. The Portuguese RAQoL was administered on two occasions, 14 days apart. Participants also completed the Nottingham Health Profile (NHP) and Health Assessment Questionnaire (HAQ) at Time 1. Internal consistency was assessed using Cronbach's alpha and reliability through Spearman's Correlation Coefficient. Construct validity was evaluated through Spearman's correlation analyses between RAQoL, NHP and HAQ. Known-group validity was tested comparing the RAQoL across different groups, considering self-perceived general health status, flare symptoms and RA severity through non-parametric tests. RESULTS: 178 RA patients (mean age 56.6, 82% female, mean disease duration 13.6 years) were included. The mean score of RAQoL was 11, with low rates of missing data (3.9%), floor (4.5%) and ceiling (2.2%) effects. Cronbach's α was 0.95 and test-retest reliability 0.92. RAQoL scores correlated moderately with scores on the NHP Physical Mobility (r=0.77), Emotional reactions (r=0.69), Pain (r=0.68) and Energy (r=0.65) section scores. RAQoL showed to be discriminative for groups according to self-perceived general health status, flare of arthritis and disease severity. CONCLUSION: The Portuguese version of the RAQoL is a valid, feasible and reliable questionnaire, suitable for use in clinical practice and research purposes.