Within a large healthcare system, the incidence of positive COVID-19 results and mortality are lower in patients on chronic hydroxychloroquine therapy

In addition to causing significant mortality and adverse changes to the quality of life of billions globally, the COVID-19 pandemic has significantly burdened healthcare systems and will continue doing so unless more-effective means of management and treatment are identified [1]. Projections estimate that, without improved treatment methods, COVID-19 could cause 100,000–240,000 deaths in the USA [1]. In vitro and in vivo studies have identified the antimalarial medicine hydroxychloroquine as a potential pharmacological treatment option [2,3,4]. Currently, hydroxychloroquine is a well-established medication prescribed to treat systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) [4].

To understand the incidence of patients with existing hydroxychloroquine prescriptions for either SLE or RA testing positive for COVID-19, data from a large healthcare system were examined.

Between 1 April 2019 and 31 March 2020, there were 1,271,014 unique patient encounters in the database. During this period, a total of 2945 COVID-19 tests were performed, with 125 (4.24%) being positive. Of the tests performed, 2849 were performed in patients without a hydroxychloroquine prescription, with 124 (4.35%) being positive; the remaining 96 tests were performed in patients with existing hydroxychloroquine prescriptions for SLE or RA, with one (1.04%) being positive. Among the COVID-19 positive patients, two (1.61%) who were not prescribed hydroxychloroquine died, but the patient who was prescribed hydroxychloroquine did not. In terms of COVID-19 testing, 0.232% of all patients within the database system were tested, whereas 5.096% of patients with hydroxychloroquine prescriptions within the system were tested.

These results make a preliminary case for using hydroxychloroquine as a form of prophylactic treatment against COVID-19, considering the lower incidence of positive tests and no mortality among patients prescribed hydroxychloroquine. Furthermore, the fact that a greater percentage of patients with a hydroxychloroquine prescription were tested might reflect providers having higher indexes of suspicion of COVID-19 in these patients. This is interesting because our expectation is that an inherently immunocompromised population, such as one prescribed hydroxychloroquine, would be more likely to contract COVID-19. That being said, further study of hydroxychloroquine is warranted to ensure its efficacy as a means of prophylactically preventing the onset or progression of COVID-19. While these data are observational in a relatively small population and a clinical trial would be most helpful, we may lose valuable time and invaluable lives while waiting for trial results, considering the projected mortality due to COVID-19. We encourage other healthcare systems to examine their own databases to see if the trends we identified can be seen more broadly (Table 1).

Table 1 Results of COVID-19 testing in patients prescribed/not prescribed hydroxychloroquine