Hydroxychloroquine treatment does not reduce COVID-19 mortality; underdosing to the wrong patients?

Abstract

An observational study published in The Lancet Rheumatology by Christopher T Rentsch and colleagues1 showed no association between pre-exposure use of hydroxychloroquine and reduced mortality in patients with COVID-19 who also have systemic lupus erythematosus or rheumatoid arthritis. 138 440 (71·1%) participants were women, and the study population was relatively young, with 50% of the participants younger than 66 years. In a previous study,2 the death rate in patients younger than 70 years was low, and it was lower for women than men; therefore, the differences in mortality might be very difficult to appreciate in the study by Rentsch and colleagues,1 in which half of the participants are under 70 years old and more than two thirds are women.