FRI0434 Blood Hydroxychloroquine (HCQ) Levels do not PREDICT Quality of Life in Systemic Lupus Erythematosus (SLE)

Background Benefits of use of HCQ on physician reported outcomes (PRO) have been well documented in SLE and Rheumatoid arthritis (RA). HCQ can be measured in blood ([HCQ]) and a target threshold of 1000ng/ml has been proposed. No studies have assessed the predictive role of [HCQ] on PRO in SLE. Objectives Assess the predictive value of [HCQ] with health related quality of life (HRQOL) among patients with SLE. Methods Data from the PLUS study (a prospective randomized, double-blind, placebo-controlled, multicentre study comparing standard and adjusted HCQ dosing schedules and [HCQ]) were utilized. Blood HCQ levels were quantified by HPLC, along with HRQOL PRO assessments (Medical Outcomes Study-Short Form 36 or SF-36) at baseline (J0) and month 7 visits (M7). Paired t test were used to compare HCQ concentrations at the two visits. Spearman correlation coefficients between HCQ concentrations (continuous variable) and HRQOL at J0 and M7 were obtained. Nonparametric t test to compare HRQOL (J0) stratified by HCQ concentrations categories (0-499, 500-1000, >1000 ng/ml) was performed. Linear regression analysis with physical or mental component summary scores as dependent variables, and HCQ (J0) concentration as the predictor variable was performed. P value of ≤0.05 on two tailed tests was considered significant. Results 166 SLE patients' data were analyzed. Mean (SD) age and disease duration were 44.4 (10.7) and 9.3 (6.8) years. Eighty seven percent were women. Mean (SD, median, IQR) HCQ concentrations in the blood at J0 were 660 (314, 615, 424) ng/ml and increased to 1020 (632, 906, 781) ng/ml at M7 (mean difference 366 units, 95% CI -472 to -260, p