Effect of Hydroxychloroquine in Hospitalized Patients with COVID-19

Background Hydroxychloroquine and chloroquine have been proposed as treatments for coronavirus disease 2019 (COVID-19) on the basis of in vitro activity, uncontrolled data, and small randomized studies. Methods The Randomised Evaluation of COVID-19 therapy (RECOVERY) trial is a randomized, controlled, open-label, platform trial comparing a range of possible treatments with usual care in patients hospitalized with COVID-19. We report the preliminary results for the comparison of hydroxychloroquine vs. usual care alone. The primary outcome was 28-day mortality. Results 1561 patients randomly allocated to receive hydroxychloroquine were compared with 3155 patients concurrently allocated to usual care. Overall, 421 (27.0%) patients allocated hydroxychloroquine and 790 (25.0%) patients allocated usual care died within 28 days (rate ratio 1.09; 95% confidence interval [CI] 0.97 to 1.23; P=0.15). Consistent results were seen in all pre-specified subgroups of patients. The results suggest that patients allocated to hydroxychloroquine may be less likely to be discharged from hospital alive within 28 days (59.9% vs. 63.0%; rate ratio 0.90; 95% CI 0.84-0.98) and that those not on invasive mechanical ventilation at baseline may be more likely to reach the composite endpoint of invasive mechanical ventilation or death (30.2% vs. 26.8%; risk ratio 1.13; 95% CI 1.02-1.25). There was no excess of new major cardiac arrhythmia. Conclusions In patients hospitalized with COVID-19, hydroxychloroquine was not associated with reductions in 28-day mortality but was associated with an increased length of hospital stay and increased risk of progressing to invasive mechanical ventilation or death. Funding Medical Research Council and NIHR (Grant ref: MC_PC_19056). Trial registrations The trial is registered with ISRCTN (50189673) and clinicaltrials.gov (NCT04381936).


INTRODUCTION
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 , emerged in China in late 2019 from a zoonotic source. 1 The majority of COVID-19 infections are either asymptomatic or result in only mild disease. However, a substantial proportion of infected individuals develop a respiratory illness requiring hospital care, 2 which can progress to critical illness with hypoxemic respiratory failure requiring prolonged ventilatory support. [3][4][5][6] Amongst COVID-19 patients admitted to UK hospitals, the case fatality rate is around 26%, and is over 37% in patients requiring invasive mechanical ventilation. 7 Hydroxychloroquine and chloroquine, 4-aminoquinoline drugs developed over 70 years ago and used to treat malaria and rheumatological conditions, have been proposed as treatments for COVID-19. Chloroquine has in vitro activity against a variety of viruses, including SARS-CoV-2 and the related SARS-CoV-1. [8][9][10][11][12][13] The exact mechanism of antiviral action is uncertain but these drugs increase the pH of endosomes that the virus uses for cell entry and also interfere with the glycosylation of the cellular receptor of SARS-CoV, angiotensin-converting enzyme 2 (ACE2), and associated gangliosides. 10,14 The 4-aminoquinoline concentrations required to inhibit SARS-CoV-2 replication in vitro are relatively high by comparison with the free plasma concentrations observed in the prevention and treatment of malaria. 15 These drugs are generally well tolerated, inexpensive and widely available. Following oral administration they are rapidly absorbed, even in severely ill patients. If active, therapeutic hydroxychloroquine concentrations could be expected in the human lung shortly after an initial loading dose.
Small pre-clinical studies have reported that hydroxychloroquine prophylaxis or treatment had no beneficial effect of clinical disease or viral replication. 16 Clinical benefit and antiviral effect from the administration of these drugs alone or in combination with azithromycin to patients with COVID-19 infections has been reported in some observational studies [17][18][19][20][21] but not in others. [22][23][24] A few small controlled trials of hydroxychloroquine or chloroquine for the treatment of COVID -19 infection have been inconclusive, whilst one larger randomized controlled trial of patients hospitalized with mild to moderate Covid-19 has reported that hydroxychloroquine 400 mg twice daily, with or without azithromycin, did not improve clinical status at day 15 as compared with usual care. [25][26][27][28][29] Here we report preliminary results of the effects of a randomized controlled trial of hydroxychloroquine in patients hospitalized with COVID-19.

Trial design and participants
The RECOVERY trial is an investigator-initiated, individually randomized, controlled, open-label, platform trial to evaluate the effects of potential treatments in patients hospitalized with COVID- The trial is coordinated by the Nuffield Department of Population Health at University of Oxford, the trial sponsor. Although the hydroxychloroquine, dexamethasone, and lopinavir-ritonavir arms have now been stopped, the trial continues to study the effects of azithromycin, tocilizumab, and convalescent plasma (and other treatments may be studied in the future).
Hospitalized patients were eligible for the study if they had clinically suspected or laboratory confirmed SARS-CoV-2 infection and no medical history that might, in the opinion of the attending clinician, put the patient at significant risk if they were to participate in the trial. Initially, recruitment was limited to patients aged at least 18 years but from 9 May 2020, the age limit was removed. Patients with known prolonged electrocardiograph QTc interval were ineligible for the hydroxychloroquine arm. Co-administration with medications that prolong the QT interval was not an absolute contraindication but attending clinicians were advised to check the QT interval by performing an electrocardiogram.
Written informed consent was obtained from all patients or from a legal representative if they were too unwell or unable to provide consent. The trial was conducted in accordance with the

Randomization
Baseline data collected using a web-based case report form included demographics, level of respiratory support, major comorbidities, the suitability of the study treatment for a particular patient, and treatment availability at the study site. Eligible and consenting patients were assigned to either usual standard of care or usual standard of care plus hydroxychloroquine or one of the other available treatment arms using web-based simple (unstratified) randomization with allocation concealment (see Supplementary Appendix). Randomization to usual care was twice that of any of the active arms the patient was eligible for (e.g. 2:1 in favor of usual care if the patient was eligible for only one active arm, 2:1:1 if the patient was eligible for two active arms, etc.) For some patients, hydroxychloroquine was unavailable at the hospital at the time of enrolment or was considered by the managing physician to be either definitely indicated or definitely contraindicated. These patients were excluded from entry in the randomized comparison between hydroxychloroquine and usual care and hence were not included in this report.
Patients allocated to hydroxychloroquine sulfate (200mg tablet containing 155mg base equivalent) received a loading dose of 4 tablets (800 mg) at zero and 6 hours, followed by 2 tablets (400 mg) starting at 12 hours after the initial dose and then every 12 hours for the next 9 days or until discharge (whichever occurred earlier) (see Supplementary Appendix). 15 Allocated treatment was prescribed by the attending clinician. Patients and local study staff were not blinded to the allocated treatment.

Procedures
A single online follow-up form was to be completed when participants were discharged, had died or at 28 days after randomization (whichever occurred earlier). Information was recorded on adherence to allocated study treatment, receipt of other study treatments, duration of admission, receipt of respiratory support (with duration and type), receipt of renal dialysis or hemofiltration, and vital status (including cause of death). From 12 May 2020, extra information was recorded on the occurrence of new major cardiac arrhythmia. In addition, routine health care and registry data were obtained including information on vital status (with date and cause of death); discharge from hospital; respiratory and renal support therapy.

Outcome measures
The primary outcome was all-cause mortality within 28 days after randomization; further analyses were specified at 6 months. Secondary outcomes were time to discharge from hospital and, among patients not on invasive mechanical ventilation at randomization, invasive mechanical ventilation (including extra-corporal membrane oxygenation) or death. Subsidiary clinical outcomes included cause-specific mortality, use of hemodialysis or hemofiltration, major cardiac arrhythmia (recorded in a subset), and receipt and duration of ventilation. All information presented is based on a data-cut of 27 July 2020. Information on the primary outcome is complete for all patients.

Statistical Analysis
For the primary outcome of 28-day mortality, the log-rank 'observed minus expected' statistic and its variance were used to both test the null hypothesis of equal survival curves and to calculate the one-step estimate of the average mortality rate ratio, comparing all patients allocated hydroxychloroquine with all patients allocated usual care. Kaplan-Meier survival curves were constructed to display cumulative mortality over the 28-day period. The same methods were used to analyze time to hospital discharge, with patients who died in hospital right-censored on day 29. Median time to discharge was derived from the Kaplan-Meier estimates. For the pre-specified composite secondary outcome of invasive mechanical ventilation or death within 28 days (among those not receiving invasive mechanical ventilation at randomization), the precise date of starting invasive mechanical ventilation was not available and so the risk ratio was estimated instead. Estimates of absolute risk differences between patients allocated hydroxychloroquine and patients allocated usual care were also calculated.
Pre-specified analyses of the primary outcome were performed in six subgroups defined by characteristics at randomization: age, sex, race, level of respiratory support, days since symptom onset, and predicted 28-day mortality risk (See Supplementary Appendix). Observed effects within subgroup categories were compared using a chi-square test for trend (which is equivalent to a test for heterogeneity for subgroups that have only two levels).
Estimates of rate and risk ratios (both hereon denoted RR) are shown with 95% confidence intervals (without adjustment for multiple testing). The p-value for the assessment of the primary outcome is 2-sided. All analyses were done according to the intention-to-treat principle. The full database is held by the study team which collected the data from study sites and performed the analyses at the Nuffield Department of Population Health, University of Oxford.

Role of the independent Data Monitoring Committee and decision to stop enrolment
The independent Data Monitoring Committee reviewed unblinded analyses of the study data and any other information considered relevant at intervals of around 2 weeks. The committee was charged with determining if, in their view, the randomized comparisons in the study provided evidence on mortality that is strong enough (with a range of uncertainty around the results that is narrow enough) to affect national and global treatment strategies. In such a circumstance, the Committee would inform the Trial Steering Committee who would make the results available to the public and amend the trial arms accordingly. Unless that happened, the Trial Steering Committee, investigators, and all others involved in the trial would remain blind to the interim results until 28 days after the last patient had been randomized to a particular intervention arm.
On 4 June, in response to a request from the MHRA, the independent Data Monitoring Committee conducted a review of the data and recommended the chief investigators review the unblinded data on the hydroxychloroquine arm of the trial. The chief investigators and Trial Steering Committee concluded that the data showed no beneficial effect of hydroxychloroquine in patients hospitalized with COVID-19. Therefore, enrolment of participants to the hydroxychloroquine arm was closed on 5 June and the preliminary result for the primary outcome was made public. Investigators were advised that any patients currently taking hydroxychloroquine as part of the study should discontinue the treatment.

Patients
Of the 11,197 patients randomized while the hydroxychloroquine arm was open (25 March to 5 June 2020), 7513 (67%) were eligible to be randomized to hydroxychloroquine (that is hydroxychloroquine was available in the hospital at the time and the attending clinician was of the opinion that the patient had no known indication for or contraindication to hydroxychloroquine) ( Figure 1 and Table S1). Of these, 1561 were randomized to hydroxychloroquine and 3155 were randomized to usual care with the remainder being randomized to one of the other treatment arms. Mean age of study participants in this comparison was 65.4 (SD 15.3) years (Table 1), 38% patients were female, and 18% were Black, Asian, or minority ethnic. No children were enrolled in the hydroxychloroquine comparison. A history of diabetes was present in 27% of patients, heart disease in 26%, and chronic lung disease in 22%, with 57% having at least one major comorbidity recorded. In this analysis, 90% of patients had laboratory confirmed SARS-CoV-2 infection, with the result currently awaited for 1%. At randomization, 17% were receiving invasive mechanical ventilation or extracorporeal membrane oxygenation, 60% were receiving oxygen only (with or without noninvasive ventilation), and 24% were receiving neither.
Among the 4681 patients with a completed follow-up form, 1425 (92%) patients allocated to hydroxychloroquine received at least 1 dose (Table S2) and the median number of days of treatment was 6 days (IQR 3 to 10 days). 12 (<0.5%) of the usual care arm received hydroxychloroquine. Use of azithromycin or other macrolide drug during the follow-up period was similar in both arms (18% vs. 20%) as was use of dexamethasone (9% vs. 9%). Remdesivir was used by <0.5% patients.

Primary outcome
There was no significant difference in the proportion of patients who met the primary outcome of 28- (Figure 2). Similar results were seen across all six pre-specified subgroups (Figure 3). In post hoc exploratory analyses restricted to the 4257 (90%) patients with a positive SARS-CoV-2 test result, the result was similar (rate ratio, 1.09, 95% CI 0.96 to 1.23).

Secondary outcomes
Allocation to hydroxychloroquine was associated with a longer time until discharge alive from hospital than usual care (median 16 days vs. 13 days) and a lower probability of discharge alive within 28 days (rate ratio 0.90, 95% CI 0.84 to 0.98) ( Table 2). Among those not on invasive mechanical ventilation at baseline, the number of patients progressing to the pre-specified composite secondary outcome of invasive mechanical ventilation or death was higher among those allocated to hydroxychloroquine (risk ratio 1.13, 95% CI 1.02 to 1.25).
Information on the occurrence of new major cardiac arrhythmia was collected for 730 (46.7%) patients in the hydroxychloroquine arm and 1413 (44.7%) in the usual care arm since these fields were added to the follow-up form on 12 May 2020. Among these patients, there were no significant differences in the frequency of supraventricular tachycardia (7.5% vs. 5.9%), ventricular tachycardia or fibrillation (0.8% vs. 0.6%) or atrioventricular block requiring intervention (0.1% vs. 0.1%) (Table S4). There was one report of a serious adverse reaction believed related to hydroxychloroquine; a case of torsades de pointes from which the patient recovered without the need for intervention. Analyses of receipt of renal dialysis or hemofiltration, and duration of ventilation will be presented once all relevant information is available.

DISCUSSION
Although preliminary, these results indicate that hydroxychloroquine is not an effective treatment for patients hospitalized with COVID-19. The lower bound of the confidence limit for the primary outcome rules out any reasonable possibility of a meaningful mortality benefit. The results were consistent across subgroups of age, sex, race, time since illness onset, level of respiratory support, and baseline-predicted risk. In addition, the results suggest that allocation to hydroxychloroquine was associated with an increase in the duration of hospitalization and an increased risk of requiring invasive mechanical ventilation or dying for those not on invasive mechanical ventilation at baseline.
RECOVERY is a large, pragmatic, randomized, controlled platform trial designed to provide rapid and robust assessment of the impact of readily available potential treatments for COVID-19 on 28-day mortality. Around 15% of all patients hospitalized with COVID-19 in the UK over the study period were enrolled in the trial and the fatality rate in the usual care arm is consistent with the hospitalized case fatality rate in the UK and elsewhere. 7,30,31 Only essential data were collected at hospital sites with additional information (including long-term mortality) ascertained through linkage with routine data sources. We did not collect information on physiological, electrocardiographic, laboratory or virologic parameters.
Hydroxychloroquine has been proposed as a treatment for COVID-19 based largely on its in vitro SARS-CoV-2 antiviral activity and on data from observational studies reporting effective reduction in viral loads. However, the 4-aminoquinoline drugs are relatively weak antivirals. 15 Demonstration of therapeutic efficacy of hydroxychloroquine in severe COVID-19 would require rapid attainment of efficacious levels of free drug in the blood and respiratory epithelium. 32 Thus, to provide the greatest chance of providing benefit in life threatening COVID-19, the dose regimen was designed to result in rapid attainment and maintenance of plasma concentrations that were as high as safely possible. 15 These concentrations were predicted to be at the upper end of those observed during steady state treatment of rheumatoid arthritis with hydroxychloroquine. 33 Our dosing schedule was based on hydroxychloroquine pharmacokinetic modelling referencing a SARS-CoV-2 half maximal effective concentration (EC 50) of 0.72 μM scaled to whole blood concentrations and an assumption that cytosolic concentrations in the respiratory epithelium are in dynamic equilibrium with blood concentrations. 8,15,34 The primary concern with short-term high dose 4-aminoquinoline regimens is cardiovascular toxicity. Hydroxychloroquine causes predictable prolongation of the electrocardiograph QT interval that is exacerbated by co-administration with azithromycin, as widely prescribed in COVID-19 treatment. [16][17][18] Although torsade de pointes has been described, serious cardiovascular toxicity has been reported very rarely despite the high prevalence of cardiovascular disease in hospitalized patients, the common occurrence of myocarditis in COVID-19, and the extensive use of hydroxychloroquine and azithromycin together. The exception is a Brazilian study which was stopped early because of cardiotoxicity. However in that study, chloroquine 600 mg base was given twice daily for ten days, a substantially higher total dose than used in other trials, including RECOVERY. 35,36 Pharmacokinetic modelling in combination with blood concentration and mortality data from a case series of 302 chloroquine overdose patients predicts that the base equivalent chloroquine regimen to the RECOVERY hydroxychloroquine regimen is safe. 36 Hydroxychloroquine is considered to be safer than chloroquine. 15 We did not observe excess mortality in the first 2 days of treatment with hydroxychloroquine, the time when early effects of dose-dependent toxicity might be expected.
Furthermore, the preliminary data presented here did not show any excess in ventricular tachycardia (including torsade de pointes) or ventricular fibrillation in the hydroxychloroquine arm.
The findings indicate that hydroxychloroquine is not an effective treatment for hospitalized patients with COVID-19 but do not address its use as prophylaxis or in patients with less severe SARS-CoV-2 infection managed in the community. A review of COVID-19 treatment guidelines produced early in the pandemic found that chloroquine or hydroxychloroquine was recommended in China, France, Italy, Netherlands, and South Korea. 37

Conflicts of interest
The authors have no conflict of interest or financial relationships relevant to the submitted work to disclose. No form of payment was given to anyone to produce the manuscript. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest.
The Nuffield Department of Population Health at the University of Oxford has a staff policy of not accepting honoraria or consultancy fees directly or indirectly from industry (see https://www.ndph.ox.ac.uk/files/about/ndph-independence-of-research-policy-jun-20.pdf). Results are count (%), mean ± standard deviation, or median (inter-quartile range). *No children (aged <18 years) were enrolled. †Includes 6 pregnant women. † † Black, Asian, or minority ethnic. ¶ All tests for difference in baseline characteristics between treatment arms give p>0.05.
The 'oxygen only' group includes non-invasive ventilation. Severe liver disease defined as requiring ongoing specialist care. Severe kidney impairment defined as estimated glomerular filtration rate <30 mL/min/1.73m 2 . 9 (0.6%) patients allocated to hydroxychloroquine and 9 (0.3%) patients allocated to usual care alone had missing data for days since symptom onset. If a person was randomized on the day of admission their 'days since admission' would be zero days.

Table 2: Effect of allocation to hydroxychloroquine on main study outcomes
RR=rate ratio for the outcomes of 28-day mortality and hospital discharge, and risk ratio for the outcome of receipt of invasive mechanical ventilation or death. CI=confidence interval.
* Analyses exclude those on invasive mechanical ventilation at randomization.