Validity and reliability of the Japanese version of LupusQoL: Assessment of disease-specific health-related quality of life in systemic lupus erythematosus

ObjectiveTo develop a Japanese version of LupusQoL (LupusQoL-JP) and assess its validity and reliability in patients with systemic lupus erythematosus (SLE).MethodsThis study consisted of two independent cross-sectional analyses using data from two different periods at our university clinic: 2011 (initial period, <i>n</i> = 266) and 2015-2018 (second period, <i>n</i> = 133). The English version of the LupusQoL was translated into Japanese and administered to Japanese patients with SLE, alongside other questionnaires, including the Medical Outcomes Study Short Form-36 (SF-36) and the 5-level EuroQoL 5-Dimensions Questionnaire (EQ-5D-5L). Physicians also completed measures such as the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (ACR) Damage Index (SDI) and SLE Disease Activity Index 2000 (SLEDAI-2K), and assessed lupus low disease activity state (LLDAS) attainment.ResultsLupusQoL-JP showed acceptable internal consistency (Cronbach's α > 0.8). All subscales, except for fatigue, demonstrated good test-retest reliability. The LupusQoL-JP and SF-36 scores were strongly correlated with comparable domains. The LupusQoL-JP subscale scores were moderately to strongly correlated with the EQ-5D-5L index values, while weakly correlated with the SDI and generally not correlated with age, disease duration, prednisolone dosage, or SLEDAI-2K. Some LupusQoL-JP domains were able to differentiate between the LLDAS and non-LLDAS groups.ConclusionLupusQoL-JP was successfully translated, adapted, and validated. It demonstrated good concurrent validity with comparable domains of the SF-36 and was independent of SLEDAI-2K. Patients with SLE in LLDAS were partly associated with better disease-specific health-related quality of life, as assessed by LupusQoL-JP.