Cross-cultural validation of a disease-specific patient-reported outcome measure for lupus in Philippines

Abstract

Objective LupusPRO is a disease-targeted patient-reported outcome measure that was developed and validated among US patients with systemic lupus erythematosus (SLE). We report the cross-cultural validation results of the LupusPRO English-language version among Filipino SLE patients. Method The 43-item LupusPRO was pretested in 15 SLE individuals, then administered to 106 SLE patients, along with short-form SF36 and the EQ5D visual analogue scale. A mail/drop-back LupusPRO and change in health status item survey were returned within two to three days. Demographics, clinical and serological characteristics, disease activity and damage measured by PGA, SELENA-SLEDAI, LFA Flare, and SLICC-ACR SLE damage index (SDI) were collected. Internal consistency reliability (ICR), test-retest reliability (TRT), convergent validity (corresponding SF36 domains) and criterion validity (against general health and disease activity measures) were tested. Reported p values are two tailed. Results A total of 121 Filipino SLE subjects (95% women, median age 31.0 ± 16 years) with at least a high school level of English instruction participated. Median (IQR) PGA, SLEDAI and SDI were 0.0 (1.0), 2.0 (10) and 0 (1), respectively. ICR exceeded 0.7 for all domains except the lupus symptoms domain. TRT was greater than 0.85 for all LupusPRO domains. Convergent and criterion validity were observed against corresponding SF36 domains and disease activity measures. The tool was well received by patients. Confirmatory factor analysis showed good fit. Conclusion English LupusPRO has fair psychometric properties among SLE patients in the Philippines, and is now available for inclusion in clinical trials and longitudinal studies to test responsiveness to change.