Background There is ample evidence demonstrating that hydroxychloroquine (HCQ) prevents lupus flares, increases long-term survival, and protects against irreversible organ damage in SLE (Pons-Estel Arth Care Res 2010). However, in recent years, ophthalmology guidelines have encouraged providers to limit cumulative HCQ exposure to prevent ocular toxicity. We examined whether a) HCQ use in our UCLA cohort has changed over time and b) whether patients who discontinue HCQ accumulate damage at a different rate than continuous or never users.
Methods SLE subjects participating in our longitudinal ‘Biomarkers of Atherosclerosis’ carotid ultrasound cohort were evaluated. Medication use (and reasons for disuse) were recorded at cohort entry, and at each subsequent study visit.
303 SLE subjects participated in the baseline study (2004–2006), 229 in the 2nd follow-up (2008–2010), and 102 in the 3rd follow-up exam (2015-present).
For continuity, SLICC Damage Index (SDI) was measured at baseline, 3 years, and 5 years after cohort entry.
Results At baseline, 69.8% of patients were taking HCQ, 62.1% at first follow-up, and 58.6% at second follow-up (p=ns). Patient preference and physician preference were the most common reasons for HCQ non-use. Less than 3% of subjects who discontinued HCQ did so due to concern for eye toxicity at baseline and first follow-up, but this increased to 7.4% at second follow-up.
We compared SDI at baseline in patients who were never HCQ users (n=29), vs previous users (n=93), vs continuously users (n=181). We found evidence of SLE-related damage (SDI≥1) in 75.9% of never HCQ users, 74.1% of previous users, and 52.4% of subjects on HCQ at baseline (p=0.001, Chi-Square). At 5 years, we found SDI≥1 in 94.7% of never HCQ users, 82.7% of previous users vs 68.2% of subjects on HCQ at baseline (p=0.004, Chi-Square).
Conclusions Although the frequency HCQ use in our longitudinal SLE cohort has decreased slightly over the last 13 years, the percentage of subjects who discontinued HCQ due to eye-related eye toxicity has increased recently. Further studies will be required to determine whether this increase is due solely to cumulative HCQ dose vs more frequent detection because of adherence to ophthalmology testing guidelines vs earlier detection due to more sensitive testing modalities. Our data also demonstrate that damage accumulation is similar in subjects who previously used HCQ and those who never used, and higher compared to continuous users, suggesting continuous HCQ use may be important for damage prevention in SLE.
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