Physicians should consider maximum HCQ dose on Ideal weight for patients who are short and obese and real weight for short, thin individuals.
COULD NOT REPLICATE THE DATA
Dr. Browning's group tried to replicate the results of Melles and Marmor by analyzing an independent database including 567 patients taking HCQ of whom 41 had retinopathy.3
"We found that for the ideal body weight method, the results mirrored those of the authors-there was higher risk at lower BMIs-but we could not replicate the results using the real body weight method (Figures 4 and 5). Instead of invariance, there was a higher risk for the real body weight method at lower BMIs," he said.
Melles and Marmor calculated receiver operating characteristic curves to assess the sensitivity and specificity of real versus ideal body weight in predicting toxicity, noting that a higher area under the curve (AUC) implies a better ability to predict retinopathy.
"They reported AUCs of 0.78 for real and 0.75 for ideal weight (Figure 6)," Dr. Browning said. "Although this difference in the two methods is statistically significant, it is clinically unimportant and achieves statistical significance by having a massive sample size (n = 2,361). Furthermore, the analysis was univariate, and it ignored the effects of covariates such as gender, age, cumulative dose, and BMI."
This article was adapted from Dr. Browning's presentation during the 2017 meeting of the American Academy of Ophthalmology. He had no disclosures that were relevant to this talk.
1. Marmor MF, Kellner U, Lai TYY, et al. AAO Statement. Recommendations on screening for chloroquine and hydroxychloroquine retinopathy 2016 revision. Ophthalmology. 2016;123:1386-1394.
2. Melles RB, Marmor MF. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA Ophthalmol. 2014;132:1453-1460.
3. Browning DJ, Lee C. Somatotype, the risk of hydroxychloroquine retinopathy, and safe daily dosing guidelines. Clinical Ophthalmology. 2018;12:811-818.