Objective In 2016, the American Academy of Ophthalmology (AAO) changed the recommended daily dose of hydroxychloroquine (HCQ) from 6.5 mg/kg to <5 mg/kg. However, it is not clear that the lower prescribed dose of HCQ will have the same efficacy for systemic lupus erythematosus (SLE) activity or the same role in protecting against cardiovascular risk factors and thrombosis. This study was undertaken to address the frequency of HCQ retinopathy and the role of HCQ blood levels in identifying those individuals who are at a greater future risk of retinopathy. Methods HCQ blood levels in 537 patients with SLE from a large clinical cohort were repeatedly measured, and patients were tested for HCQ retinopathy. We assessed the risk of retinopathy according to clinical characteristics and blood levels of HCQ. Results The overall frequency of retinopathy was 4.3% (23 of 537 patients). There was a 1% risk of retinopathy in the first 5 years of HCQ treatment, 1.8% from 6 to 10 years, 3.3% from 11 to 15 years, 11.5% from 16 to 20 years, and 8.0% after 21 years of use. We found that older age (P < 0.0001), higher body mass index (P for trend = 0.0160), and longer duration of HCQ intake (P = 0.0024 and P for trend = 0.0006) were associated with a higher risk of HCQ toxicity. Higher blood levels of HCQ predicted later HCQ retinopathy (P = 0.0124 and P = 0.0340 for mean and maximum HCQ blood levels, respectively). Conclusion Our data prove the utility of assessing blood levels of HCQ in the prediction of retinopathy. This would allow clinicians to either decrease the dose or increase monitoring in those patients with high HCQ blood levels.

Objective. Hydroxychloroquine (HCQ) has a primary role in the prophylaxis and treatment of systemic lupus erythematosus (SLE) and may be protective against thrombosis in SLE. Optimal weight-based dosing of HCQ is unknown. This study was undertaken to examine the usefulness of HCQ blood monitoring in predicting thrombosis risk in a longitudinal SLE cohort.Methods. HCQ levels were serially quantified from EDTA whole blood by liquid chromatography-tandem mass spectrometry. The mean HCQ blood levels calculated prior to thrombosis or until the last visit were compared using t-tests between patients with and those without thrombosis. Pooled logistic regression was used to analyze the association between rates of thrombosis and HCQ blood level. Rate ratios (RRs) and 95% confidence intervals (95% CIs) were calculated.Results. In 739 patients with SLE, thrombosis occurred in 38 patients (5.1%). The mean ± SD HCQ blood level was lower in patients who developed thrombosis versus those who did not develop thrombosis (720 ± 489 ng/ml versus 935 ± 580 ng/ml; P = 0.025). Thrombosis rates were reduced by 13% for every 200-ng/ml increase in the most recent HCQ blood level (RR 0.87 [95% CI 0.78-0.98], P = 0.025) and by 13% for mean HCQ blood level (RR 0.87 [95% CI 0.76-1.00], P = 0.056). Thrombotic events were reduced by 69% in patients with mean HCQ blood levels ≥1,068 ng/ml versus those with levels <648 ng/ml (RR 0.31 [95% CI 0.11-0.86], P = 0.024). This remained significant after adjustment for confounders (RR 0.34 [95% CI 0.12-0.94], P = 0.037). Conclusion.Low HCQ blood levels are associated with thrombotic events in SLE. Longitudinal measurement of HCQ levels may allow for personalized HCQ dosing strategies. Recommendations for empirical dose reduction may reduce or eliminate the benefits of HCQ in this high-risk population.

Aim The Lupus Low Disease Activity State (LLDAS) is a potential treat to target goal in systemic lupus erythematosus (SLE). SLE patients in LLDAS for more than half of the observation time have about a 50% lower risk of new organ damage and have reduced mortality. We identified predictors of being in LLDAS ≥50% of the observation time. Methods A total of 2228 SLE patients who had at least three clinical visits were included. Percentage of time in LLDAS was calculated based on the proportion of days under observation. LLDAS-50 was defined as being in LLDAS for ≥50% of the observation time. We used the stepwise selection procedure in logistic regression to identify predictors of LLDAS-50. Results A total of 1169 (52.5%) SLE patients, but only 37.6% of African Americans, achieved LLDAS-50. In the multivariable model, African American ethnicity, hypocomplementemia, serositis, renal activity, arthritis, anti-RNP, anti-dsDNA, vasculitis, malar rash, discoid rash, thrombocytopenia, and immunosuppressive use were negative predictors of LLDAS-50. Older age at diagnosis, longer disease duration, higher education level, and greater percentage of time taking hydroxychloroquine remained positive predictors of LLDAS-50. Conclusion In this large cohort, only 52.5% achieved LLDAS-50. This proportion was even less in African Americans. A higher percentage of time taking hydroxychloroquine was a modifiable positive predictor of LLDAS-50. Anti-RNP, anti-dsDNA, and low complement were negatively associated with LLDAS-50. Our findings further emphasize the importance of inclusion of African Americans in clinical trials and hydroxychloroquine adherence in both clinical practice and clinical trials.