Physicians should consider maximum HCQ dose on Ideal weight for patients who are short and obese and real weight for short, thin individuals.
Recent years have brought major changes to the recommendations on screening patients for chloroquine and hydroxychloroquine (HCQ) retinopathy.
Daily dosing is the only modifiable risk factor. Previous guidance from 2011 said this was unimportant, except in short obese patients and recommended <6.5 mg/kg of ideal body weight, said David J. Browning, MD, PhD.
In 2016, the AAO revised its recommendations, stating that patients taking doses >5.0 mg/kg of real body weight per day were at greater risk of developing toxicity.1
"Real weight correlates better with risk compared with ideal weight," the authors stated.
WHERE DOES THE GUIDANCE COME FROM?
The real weight guidance is based on data from a retrospective chart review of 2,361 patients who had taken HCQ for >5 years; authors Melles and Marmor used logistic regression and receiver operating curves to analyze the data,2 Dr. Browning noted.
The risk of retinopathy as per body habitus indicated by body mass index (BMI) based on ideal weight showed the risk was greater for aesthenic somatotypes.
"This was not the case, however, when they looked at real body weight-instead there was an invariant risk over BMI (Figures 1 and 2)," he said.
When the two graphs are plotted on the same axis, the data reveal that for obese patients with BMIs >30 kg/m2, the ideal body weight method yields lower risk (Figure 3).
"This presents a paradoxical situation in which the guidelines encourage the real weight method using a new threshold of 5 mg/kg, but the data show that dose increases the risk of toxicity in patients who are obese," Dr. Browning said.
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.