Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial

IMPORTANCE

The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive.

OBJECTIVE

To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021.

INTERVENTIONS

The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916).

MAIN OUTCOMES AND MEASURES

The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events.

RESULTS

Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group.

CONCLUSIONS AND RELEVANCE

Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02735707.

Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial

IMPORTANCE

The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive.

OBJECTIVE

To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021.

INTERVENTIONS

The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916).

MAIN OUTCOMES AND MEASURES

The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events.

RESULTS

Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group.

CONCLUSIONS AND RELEVANCE

Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02735707.

Risk of bleeding and use of platelet transfusions in patients with hematologic malignancies: recurrent event analysis

A recent randomized trial (TOPPS) compared prophylactic platelet transfusions (for counts <10×10(9)/L) with a strategy of no-prophylaxis in adults with hematologic malignancies. Seventy percent of enrolled patients received an autologous hematopoietic stem cell transplant. Statistical models were developed to explore which patient factors or clinical characteristics are important prognostic factors for bleeding. These models were presented for baseline characteristics and for recurrent analysis of bleeding to assess the risks of World Health Organization grade 2-4 bleeding on any given day. Additional analyses explored the importance of fever. Treatment plan (chemotherapy/allogeneic hematopoietic stem cell transplant), female sex, and treatment arm (no-prophylaxis) were significantly associated with an increased number of days of bleeding. The number of days with a platelet count <10×109/L was significantly associated with a grade 2-4 bleed (P<0.0001). Patients with a temperature of at least 38°C had the highest hazard of a grade 2-4 bleed (hazard ratio: 1.7, 95% confidence interval: 1.3 to 2.4, compared with the risk in patients with a temperature <37.5°C). There was no evidence that minor bleeding predicted a grade 2-4 bleed. The results highlighted the limited role of correction of thrombocytopenia by platelet transfusion in reducing the risk of bleeding. Clinically stable patients undergoing autologous hematopoietic stem cell transplantation had the lowest risk of bleeding and benefited least from prophylactic platelet transfusions. Prospective studies are required to address the usefulness of risk factors to support better targeted platelet transfusions. TOPPS Controlled-Trials.com number ISRCTN08758735.

AUGMENTATION OF THE EXTRACARDIAC ANASTOMOSES OF THE CORONARY ARTERIES THROUGH PERICARDIAL ADHESIONS

The examination of four hearts, with partial or complete obliteration of the pericardial sac by fibrous adhesions, after injection of the coronary arteries with a colloidal suspension of lamp black showed that the extracardiac anastomoses of the coronary arteries were increased owing to the presence of adhesions. In all four instances a particularly rich injection of the parietal pericardium was obtained and microscopic examination of the adhesions showed them to contain injected vessels, extending from epicardium to parietal pericardium. A microscopic study of cleared blocks (3 mm. in thickness) of myocardium and attached pericardial adhesions, showed the arborization and anastomosis of branches of the arteries of the parietal pericardium with those of the heart. This vascularization was not limited to the usual areas of subepicardial fat, but was seen in regions not ordinarily containing arterial branches. In no one of the four cases were the coronary arteries significantly diseased. In one of the four cases, the normal sites of anastomoses between the cardiac and extracardiac vessels were destroyed by cutting away the great vessels entering and leaving the heart, as well as the peri- and intervascular reflections of parietal pericardium. Injection mass was found however, in the arteries of the parietal pericardium and the diaphragm, showing that it has passed directly through the adhesions from coronary to extracardiac vessels. If the extracardiac anastomoses of the coronary arteries constitute a significant reserve for cardiac circulation, it would appear that this reserve would be augmented by the presence of pericardial adhesions. Direct communication between branches of the coronary arteries and the pericardial branches of the internal mammary arteries with free anastomosis with the anterior branches of the thoracic aorta is established over areas corresponding to the extent of the adhesions. Work is now in progress in this laboratory to study the functional significance of such an experimentally induced collateral circulation in experimental coronary occlusion.

THE EXTRACARDIAC ANASTOMOSES OF THE CORONARY ARTERIES

Widespread anastomoses of the auricular branches and the coronary branches to the pericardial fat with the pericardiacophrenic branches of the internal mammary arteries and the anterior mediastinal, pericardial, bronchial, superior and inferior phrenic, intercostal and esophageal branches of the aorta have been described. The most extensive anastomoses between the cardiac and extracardiac vessels are around the ostia of the pulmonary veins. It was possible not only to demonstrate the passage of injection mass from the coronary arteries into the vessels of surrounding structures, but also to show vessels in the heart injected through the thoracic branches of the aorta. This rich potential extracardiac coronary collateral circulation is probably of significance in compensating for sclerosis of the large trunks of the coronary arteries.

The Ross procedure in children and young adults with congenital aortic valve disease

METHODS

Thirty-three children and young adults with congenital aortic valve disease underwent pulmonary autograft replacement of the aortic valve between October 1993 and March 1997. There wer six females and 27 males; at operation, median age was 16 years (range: 3 to 41 years) and median body weight 60 kg (range: 14 to 121 kg). Fifteen patients (46%) had undergone one or more previous cardiac surgical procedures. A bicuspid aortic valve was present in 31 patients (94%); moderate to severe aortic stenosis and regurgitation was present in 10 (30%) and 26 (79%), respectively.

RESULTS

All patients underwent the Ross procedure while in NYHA class I (64%) or class II (36%). A preoperative shortening fraction of 41 +/- 1.4% suggested well-preserved systolic function, but the mean left ventricular end-diastolic pressure of 16.6 +/- 1.3 mmHg was consistent with preoperative left ventricular pressure and volume overload. The aortic root was replaced using an interrupted suture technique in two patients and with three separate running sutures in 31. The right ventricular outflow tract was reconstructed in all classes with a cryopreserved pulmonary homograft valved conduit (median diameter 23 mm; range 19 to 30 mm). Intraoperative complications included transient atrioventricular dissociation (one), permanent atrioventricular dissociation (one), and left coronary artery distortion relieved by shortening the distal ascending aorta (one). Postoperatively, postpericardiotomy syndrome developed in six patients (18%), supraventricular tachycardia in three (9%), and ventricular tachycardia in one (3%). At three days after surgery, one patient developed ischemic left ventricular dysfunction requiring repositioning of the distorted left coronary artery higher on the neo-aortic root. Hospital survival rate was 100%. During a median follow-up of 17 months (range: 1 to 41 months) one patient suffered a non-cardiac death due to blunt trauma. there has been a significant postoperative improvement in NYHA class among surviving patients (class I, 94%; class II, 6%; p = 0.004 versus preoperative). Postoperative aortic regurgitation was absent or trivial in 17 (60%) and mild in the remaining 11 (40%) patients for whom follow-up echocardiographic data are available. One patient required reoperation 16.5 months after the Ross procedure to replace a rapidly degenerating pulmonary homograft, and one with moderately severe homograft stenosis and five with mild homograft stenosis are being monitored. Postoperatively, a gradual early expansion in the diameter of the neo-aortic root and reduction in echocardiographic indices of left ventricular hypertrophy and dilatation occurred.

CONCLUSIONS

Pulmonary autograft replacement of the aortic valve in young patients with congenital aortic valve disease has produced excellent short-term anatomic/physiologic results and symptomatic relief with no mortality. Indices of left ventricular dilatation and hypertrophy regress after repair when the Ross operation precedes important deterioration in preoperative ventricular function. Important technical considerations include: (i) the native distal ascending aorta should be sufficiently shortened before performing the distal aortic anastomosis; and (ii) the left coronary anastomosis should be positioned relatively high on the neo-aortic root with a slight amount of tension. Both of these maneuvers reduce the likelihood of coronary artery distortion. Rapid degeneration of the pulmonary homograft and the propensity towards progressive dilatation of the neo-aorta are important postoperative considerations. Until more is known about the etiology and natural history of these two potential complications, postoperative anti-inflammatory and/or immunosuppressive therapy and strict control of hypertension should be strongly considered.