Lower vs Higher Oxygenation Target and Days Alive Without Life Support in COVID-19: The HOT-COVID Randomized Clinical Trial

Importance

Supplemental oxygen is ubiquitously used in patients with COVID-19 and severe hypoxemia, but a lower dose may be beneficial.

Objective

To assess the effects of targeting a Pao2 of 60 mm Hg vs 90 mm Hg in patients with COVID-19 and severe hypoxemia in the intensive care unit (ICU).

Design, Setting, and Participants

Multicenter randomized clinical trial including 726 adults with COVID-19 receiving at least 10 L/min of oxygen or mechanical ventilation in 11 ICUs in Europe from August 2020 to March 2023. The trial was prematurely stopped prior to outcome assessment due to slow enrollment. End of 90-day follow-up was June 1, 2023.

Interventions

Patients were randomized 1:1 to a Pao2 of 60 mm Hg (lower oxygenation group; n = 365) or 90 mm Hg (higher oxygenation group; n = 361) for up to 90 days in the ICU.

Main Outcomes and Measures

The primary outcome was the number of days alive without life support (mechanical ventilation, circulatory support, or kidney replacement therapy) at 90 days. Secondary outcomes included mortality, proportion of patients with serious adverse events, and number of days alive and out of hospital, all at 90 days.

Results

Of 726 randomized patients, primary outcome data were available for 697 (351 in the lower oxygenation group and 346 in the higher oxygenation group). Median age was 66 years, and 495 patients (68%) were male. At 90 days, the median number of days alive without life support was 80.0 days (IQR, 9.0-89.0 days) in the lower oxygenation group and 72.0 days (IQR, 2.0-88.0 days) in the higher oxygenation group (P = .009 by van Elteren test; supplemental bootstrapped adjusted mean difference, 5.8 days [95% CI, 0.2-11.5 days]; P = .04). Mortality at 90 days was 30.2% in the lower oxygenation group and 34.7% in the higher oxygenation group (risk ratio, 0.86 [98.6% CI, 0.66-1.13]; P = .18). There were no statistically significant differences in proportion of patients with serious adverse events or in number of days alive and out of hospital.

Conclusion and Relevance

In adult ICU patients with COVID-19 and severe hypoxemia, targeting a Pao2 of 60 mm Hg resulted in more days alive without life support in 90 days than targeting a Pao2 of 90 mm Hg.

Trial Registration

ClinicalTrials.gov Identifier: NCT04425031.

A survey of preferences for respiratory support in the intensive care unit for patients with acute hypoxaemic respiratory failure

BACKGROUND

When caring for mechanically ventilated adults with acute hypoxaemic respiratory failure (AHRF), clinicians are faced with an uncertain choice between ventilator modes allowing for spontaneous breaths or ventilation fully controlled by the ventilator. The preferences of clinicians managing such patients, and what motivates their choice of ventilator mode, are largely unknown. To better understand how clinicians' preferences may impact the choice of ventilatory support for patients with AHRF, we issued a survey to an international network of intensive care unit (ICU) researchers.

METHODS

We distributed an online survey with 32 broadly similar and interlinked questions on how clinicians prioritise spontaneous or controlled ventilation in invasively ventilated patients with AHRF of different severity, and which factors determine their choice.

RESULTS

The survey was distributed to 1337 recipients in 12 countries. Of these, 415 (31%) completed the survey either fully (52%) or partially (48%). Most respondents were identified as medical specialists (87%) or physicians in training (11%). Modes allowing for spontaneous ventilation were considered preferable in mild AHRF, with controlled ventilation considered as progressively more important in moderate and severe AHRF. Among respondents there was strong support (90%) for a randomised clinical trial comparing spontaneous with controlled ventilation in patients with moderate AHRF.

CONCLUSIONS

The responses from this international survey suggest that there is clinical equipoise for the preferred ventilator mode in patients with AHRF of moderate severity. We found strong support for a randomised trial comparing modes of ventilation in patients with moderate AHRF.

Long-term outcomes in COVID-19 patients admitted to intensive care in Denmark: A nationwide observational study

BACKGROUND

Among ICU patients with COVID-19, it is largely unknown how the overall outcome and resource use have changed with time, different genetic variants, and vaccination status.

METHODS

For all Danish ICU patients with COVID-19 from March 10, 2020 to March 31, 2022, we manually retrieved data on demographics, comorbidities, vaccination status, use of life support, length of stay, and vital status from medical records. We compared patients based on the period of admittance and vaccination status and described changes in epidemiology related to the Omicron variant.

RESULTS

Among all 2167 ICU patients with COVID-19, 327 were admitted during the first (March 10-19, 2020), 1053 during the second (May 20, 2020 to June 30, 2021) and 787 during the third wave (July 1, 2021 to March 31, 2022). We observed changes over the three waves in age (median 72 vs. 68 vs. 65 years), use of invasive mechanical ventilation (81% vs. 58% vs. 51%), renal replacement therapy (26% vs. 13% vs. 12%), extracorporeal membrane oxygenation (7% vs. 3% vs. 2%), duration of invasive mechanical ventilation (median 13 vs. 13 vs. 9 days) and ICU length of stay (median 13 vs. 10 vs. 7 days). Despite these changes, 90-day mortality remained constant (36% vs. 35% vs. 33%). Vaccination rates among ICU patients were 42% as compared to 80% in society. Unvaccinated versus vaccinated patients were younger (median 57 vs. 73 years), had less comorbidity (50% vs. 78%), and had lower 90-day mortality (29% vs. 51%). Patient characteristics changed significantly after the Omicron variant became dominant including a decrease in the use of COVID-specific pharmacological agents from 95% to 69%.

CONCLUSIONS

In Danish ICUs, the use of life support declined, while mortality seemed unchanged throughout the three waves of COVID-19. Vaccination rates were lower among ICU patients than in society, but the selected group of vaccinated patients admitted to the ICU still had very severe disease courses. When the Omicron variant became dominant a lower fraction of SARS-CoV-2 positive patients received COVID treatment indicating other causes for ICU admission.

Haloperidol for the Treatment of Delirium in ICU Patients

BACKGROUND

Haloperidol is frequently used to treat delirium in patients in the intensive care unit (ICU), but evidence of its effect is limited.

METHODS

In this multicenter, blinded, placebo-controlled trial, we randomly assigned adult patients with delirium who had been admitted to the ICU for an acute condition to receive intravenous haloperidol (2.5 mg 3 times daily plus 2.5 mg as needed up to a total maximum daily dose of 20 mg) or placebo. Haloperidol or placebo was administered in the ICU for as long as delirium continued and as needed for recurrences. The primary outcome was the number of days alive and out of the hospital at 90 days after randomization.

RESULTS

A total of 1000 patients underwent randomization; 510 were assigned to the haloperidol group and 490 to the placebo group. Among these patients, 987 (98.7%) were included in the final analyses (501 in the haloperidol group and 486 in the placebo group). Primary outcome data were available for 963 patients (97.6%). At 90 days, the mean number of days alive and out of the hospital was 35.8 (95% confidence interval [CI], 32.9 to 38.6) in the haloperidol group and 32.9 (95% CI, 29.9 to 35.8) in the placebo group, with an adjusted mean difference of 2.9 days (95% CI, -1.2 to 7.0) (P = 0.22). Mortality at 90 days was 36.3% in the haloperidol group and 43.3% in the placebo group (adjusted absolute difference, -6.9 percentage points [95% CI, -13.0 to -0.6]). Serious adverse reactions occurred in 11 patients in the haloperidol group and in 9 patients in the placebo group.

CONCLUSIONS

Among patients in the ICU with delirium, treatment with haloperidol did not lead to a significantly greater number of days alive and out of the hospital at 90 days than placebo. (Funded by Innovation Fund Denmark and others; AID-ICU ClinicalTrials.gov number, NCT03392376; EudraCT number, 2017-003829-15.).

Restriction of Intravenous Fluid in ICU Patients with Septic Shock

BACKGROUND

Intravenous fluids are recommended for the treatment of patients who are in septic shock, but higher fluid volumes have been associated with harm in patients who are in the intensive care unit (ICU).

METHODS

In this international, randomized trial, we assigned patients with septic shock in the ICU who had received at least 1 liter of intravenous fluid to receive restricted intravenous fluid or standard intravenous fluid therapy; patients were included if the onset of shock had been within 12 hours before screening. The primary outcome was death from any cause within 90 days after randomization.

RESULTS

We enrolled 1554 patients; 770 were assigned to the restrictive-fluid group and 784 to the standard-fluid group. Primary outcome data were available for 1545 patients (99.4%). In the ICU, the restrictive-fluid group received a median of 1798 ml of intravenous fluid (interquartile range, 500 to 4366); the standard-fluid group received a median of 3811 ml (interquartile range, 1861 to 6762). At 90 days, death had occurred in 323 of 764 patients (42.3%) in the restrictive-fluid group, as compared with 329 of 781 patients (42.1%) in the standard-fluid group (adjusted absolute difference, 0.1 percentage points; 95% confidence interval [CI], -4.7 to 4.9; P = 0.96). In the ICU, serious adverse events occurred at least once in 221 of 751 patients (29.4%) in the restrictive-fluid group and in 238 of 772 patients (30.8%) in the standard-fluid group (adjusted absolute difference, -1.7 percentage points; 99% CI, -7.7 to 4.3). At 90 days after randomization, the numbers of days alive without life support and days alive and out of the hospital were similar in the two groups.

CONCLUSIONS

Among adult patients with septic shock in the ICU, intravenous fluid restriction did not result in fewer deaths at 90 days than standard intravenous fluid therapy. (Funded by the Novo Nordisk Foundation and others; CLASSIC ClinicalTrials.gov number, NCT03668236.).

Long term cognitive and functional status in Danish ICU patients with COVID-19

Background

ICU admission due to COVID‐19 may result in cognitive and physical impairment. We investigated the long‐term cognitive and physical status of Danish ICU patients with COVID‐19.

Methods

We included all patients with COVID‐19 admitted to Danish ICUs between March 10 and May 19, 2020. Patients were the contacted prospectively at 6 and 12 months for follow‐up. Our primary outcomes were cognitive function and frailty at 6 and 12 months after ICU admission, estimated by the Mini Montreal Cognitive Assessment, and the Clinical Frailty Scale. Secondary outcomes were 6‐ and 12‐month mortality, health‐related quality of life (HRQoL) assessed by EQ‐5D‐5L, functional status (Barthel activities of daily living and Lawton–Brody instrumental activities of daily living), and fatigue (Fatigue Assessment Scale). The study had no information on pre‐ICU admission status for the participants.

Results

A total of 326 patients were included. The 6‐ and 12‐month mortality was 37% and 38%, respectively. Among the 204 six‐month survivors, 105 (51%) participated in the 6‐month follow‐up; among the 202 twelve‐month survivors, 95 (47%) participated in the 12‐month follow‐up. At 6 months, cognitive scores indicated impairment for 26% (95% confidence interval [CI], 11.4–12.4) and at 12 months for 17% (95% CI, 12.0–12.8) of participants. Frailty was indicated in 20% (95% CI, 3.4–3.9) at 6 months, and for 18% (95% CI, 3.3–3.8) at 12 months. Fatigue was reported by 52% at 6 months, and by 47% at 12 months. For HRQoL, moderate, severe, or extreme health problems were reported by 28% at 6 months, and by 25% at 12 months.

Conclusion

Long‐term cognitive, functional impairment was found in up to one in four of patients surviving intensive care for COVID‐19. Fatigue was present in nearly half the survivors at both 6 and 12 months. However, pre‐ICU admission status of the patients was unknown.

Agents intervening against delirium in the intensive care unit trial-Protocol for a secondary Bayesian analysis

Background

Delirium is highly prevalent in the intensive care unit (ICU) and is associated with high morbidity and mortality. The antipsychotic haloperidol is the most frequently used agent to treat delirium although this is not supported by solid evidence. The agents intervening against delirium in the intensive care unit (AID‐ICU) trial investigates the effects of haloperidol versus placebo for the treatment of delirium in adult ICU patients.

Methods

This protocol describes the secondary, pre‐planned Bayesian analyses of the primary and secondary outcomes up to day 90 of the AID‐ICU trial. We will use Bayesian linear regression models for all count outcomes and Bayesian logistic regression models for all dichotomous outcomes. We will adjust for stratification variables (site and delirium subtype) and use weakly informative priors supplemented with sensitivity analyses using sceptical priors. We will present results as absolute differences (mean differences and risk differences) and relative differences (ratios of means and relative risks). Posteriors will be summarised using median values as point estimates and percentile‐based 95% credibility intervals. Probabilities of any benefit/harm, clinically important benefit/harm and clinically unimportant differences will be presented for all outcomes.

Discussion

The results of this secondary, pre‐planned Bayesian analysis will complement the primary frequentist analysis of the AID‐ICU trial and facilitate a nuanced and probabilistic interpretation of the trial results.

Distribution of delirium motor subtypes in the intensive care unit: a systematic scoping review

Background

Delirium is the most common cerebral dysfunction in the intensive care unit (ICU) and can be subdivided into a hypoactive, hyperactive, or mixed motor subtype based on the clinical manifestation. The aim of this review was to describe the distribution, pharmacological interventions, and outcomes of delirium motor subtypes in ICU patients.

Methods

This systematic scoping review was performed according to the PRISMA-ScR and Cochrane guidelines. We performed a systematic search in six major databases to identify relevant studies. A meta-regression analysis was performed where pooled estimates with 95% confidence intervals were computed by a random effect model.

Results

We included 131 studies comprising 13,902 delirious patients. There was a large between-study heterogeneity among studies, including differences in study design, setting, population, and outcome reporting. Hypoactive delirium was the most prevalent delirium motor subtype (50.3% [95% CI 46.0–54.7]), followed by mixed delirium (27.7% [95% CI 24.1–31.3]) and hyperactive delirium (22.7% [95% CI 19.0–26.5]). When comparing the delirium motor subtypes, patients with mixed delirium experienced the longest delirium duration, ICU and hospital length of stay, the highest ICU and hospital mortality, and more frequently received administration of specific agents (antipsychotics, α2-agonists, benzodiazepines, and propofol) during ICU stay. In studies with high average age for delirious patients (> 65 years), patients were more likely to experience hypoactive delirium.

Conclusions

Hypoactive delirium was the most prevalent motor subtype in critically ill patients. Mixed delirium had the worst outcomes in terms of delirium duration, length of stay, and mortality, and received more pharmacological interventions compared to other delirium motor subtypes. Few studies contributed to secondary outcomes; hence, these results should be interpreted with care. The large between-study heterogeneity suggests that a more standardized methodology in delirium research is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03931-3.

Management of acute atrial fibrillation in the intensive care unit: An international survey

BACKGROUND

Atrial fibrillation (AF) is common in intensive care unit (ICU) patients and is associated with poor outcomes. Different management strategies exist, but the evidence is limited and derived from non-ICU patients. This international survey of ICU doctors evaluated the preferred management of acute AF in ICU patients.

METHOD

We conducted an international online survey of ICU doctors with 27 questions about the preferred management of acute AF in the ICU, including antiarrhythmic therapy in hemodynamically stable and unstable patients and use of anticoagulant therapy.

RESULTS

A total of 910 respondents from 70 ICUs in 14 countries participated in the survey with 24%-100% of doctors from sites responding. Most ICUs (80%) did not have a local guideline for the management of acute AF. The preferred first-line strategy for the management of hemodynamically stable patients with acute AF was observation (95% of respondents), rhythm control (3%), or rate control (2%). For hemodynamically unstable patients, the preferred strategy was observation (48%), rhythm control (48%), or rate control (4%). Overall, preferred antiarrhythmic interventions included amiodarone, direct current cardioversion, beta-blockers other than sotalol, and magnesium in that order. A total of 67% preferred using anticoagulant therapy in ICU patients with AF, among whom 61% preferred therapeutic dose anticoagulants and 39% prophylactic dose anticoagulants.

CONCLUSION

This international survey indicated considerable practice variation among ICU doctors in the clinical management of acute AF, including the overall management strategies and the use of antiarrhythmic interventions and anticoagulants.

Long-term cognitive and pulmonary functions following a lower versus a higher oxygenation target in the HOT-ICU trial: protocol and statistical analysis plan

BACKGROUND

Although supplemental oxygen can be lifesaving, liberal oxygen administration causing hyperoxaemia may be harmful. The targets for oxygenation in patients with acute hypoxaemic respiratory failure acutely admitted to the intensive care unit (ICU) are strongly debated, and consensus on which targets to recommend has not been reached. The Handling Oxygenation Targets in the ICU (HOT-ICU) trial is a multicentre, randomised, parallel-group trial of a lower oxygenation target (arterial partial pressure of oxygen [PaO₂ ] = 8 kPa) versus a higher oxygenation target (PaO₂  = 12 kPa) in adult ICU patients with acute hypoxaemic respiratory failure. In this study, we aim to evaluate the effects of these targets on long-term cognitive and pulmonary function in Danish patients, enrolled in the HOT-ICU trial and surviving to 1-year follow-up. We hypothesise that a lower oxygenation target throughout the ICU stay may result in cognitive impairment, whereas a higher oxygenation target may result in impaired pulmonary function.

METHODS

All patients enrolled in the HOT-ICU trial at Danish sites and surviving to 1 year after randomisation are eligible to participate. The last patient is expected to be included by November 2021. A Repeatable Battery for the Assessment of Neuropsychological Status and a body plethysmography, including diffusion capacity for carbon monoxide, both pre-planned secondary long-term outcomes of the HOT-ICU trial, will be obtained.

CONCLUSION

This study will provide important information on the long-term effects of a lower versus a higher oxygenation target on cognitive and pulmonary function in adult ICU patients with acute hypoxaemic respiratory failure.

Health-related quality of life, anxiety and depression and physical recovery after critical illness - A prospective cohort study

BACKGROUND

Critical illness is often followed by mental and physical impairments. We aimed to assess the health-related quality of life (HRQoL), symptoms of anxiety and depression, and physical function in critically ill patients after discharge from the intensive care unit.

METHODS

For this prospective cohort study we included all available adult patients admitted to the ICU for >24 h during a 12-month period. Home visits took place at 3 and 12 months after discharge from the hospital and included Short-Form Health Survey (SF-36), Hospital Anxiety and Depression Scale, and Chelsea Critical Care Assessment Too (CPAx).

RESULTS

We visited 79 patients at 3 and 53 at 12 months. In patients with data from both visits the mental components SF-36 scores (median (IQR)) were 55 (43-63) at 3, and 58.5 (49.5-64) at 12 months; physical component SF-36 scores were 35 (28-45) at 3, and 36 (28-42) at 12 months. SF-36 subdomains of mental health, social functioning, and role emotional were close to normal. Vitality, bodily pain, general health, physical functioning, and role physical were severely affected. Incidences of anxiety and depression symptoms were 16%/8% at 3 and 13%/8% at 12 months) and physical function (CPAx) was 47 at both time points).

CONCLUSION

We found no change in HRQoL, anxiety, and depression, or physical function from 3 months to 1 year. Physical health-related quality of life was impaired at both time points. Subdomain scores for physical health-related quality of life were affected more than mental domains at both time points.

Interactions in clinical trials: Protocol and statistical analysis plan for an explorative study of four randomized ICU trials on use of pantoprazole, oxygenation targets, haloperidol and intravenous fluids

BACKGROUND

Intensive care unit (ICU) patients receive numerous interventions, but knowledge about potential interactions between these interventions is limited. Co-enrolment in randomized clinical trials represents a unique opportunity to investigate any such interactions. We aim to assess interactions in four randomized clinical trials with overlap in inclusion periods and patient populations.

METHODS

This protocol and statistical analysis plan describes a secondary explorative analysis of interactions in four international ICU trials on pantoprazole, oxygenations targets, haloperidol and intravenous fluids, respectively. The primary outcome will be 90-day all-cause mortality. The secondary outcome will be days alive and out of hospital in 90 days after randomization. All patients included in the intention-to-treat populations of the four trials will be included. Four co-primary analyses will be conducted, one with each of the included trials as reference using a logistic regression model adjusted for the reference trial's stratification variables and for the co-interventions with interactions terms. The primary analytical measure of interest will be the analyses' tests of interaction. A p-value below .05 will be considered statically significant. The stratification variable- and co-intervention-adjusted effect estimates will be reported with 95% confidence intervals without adjustments for multiplicity.

CONCLUSION

This exploratory analysis will investigate the presence of any interactions between pantoprazole, oxygenation targets, haloperidol and amount of intravenous fluids in four international ICU trials using co-enrolment. Assessment of possible interactions represents valuable information to guide the design, statistical powering and conduct of future trials.

Oxygenation targets in ICU patients with COVID-19: A post hoc subgroup analysis of the HOT-ICU trial

Background

Supplemental oxygen is the key intervention for severe and critical COVID‐19 patients. With the unstable supplies of oxygen in many countries, it is important to define the lowest safe dosage.

Methods

In spring 2020, 110 COVID‐19 patients were enrolled as part of the Handling Oxygenation Targets in the ICU trial (HOT‐ICU). Patients were allocated within 12 h of ICU admission. Oxygen therapy was titrated to a partial pressure of arterial oxygen (PaO₂) of 8 kPa (lower oxygenation group) or a PaO₂ of 12 kPa (higher oxygenation group) during ICU stay up to 90 days. We report key outcomes at 90 days for the subgroup of COVID‐19 patients.

Results

At 90 days, 22 of 54 patients (40.7%) in the lower oxygenation group and 23 of 55 patients (41.8%) in the higher oxygenation group had died (adjusted risk ratio: 0.87; 95% confidence interval, 0.58–1.32). The percentage of days alive without life support was significantly higher in the lower oxygenation group (p = 0.03). The numbers of severe ischemic events were low with no difference between the two groups. Proning and inhaled vasodilators were used more frequently, and the positive end‐expiratory pressure was higher in the higher oxygenation group. Tests for interactions with the results of the remaining HOT‐ICU population were insignificant.

Conclusions

Targeting a PaO₂ of 8 kPa may be beneficial in ICU patients with COVID‐19. These results come with uncertainty due to the low number of patients in this unplanned subgroup analysis, and insignificant tests for interaction with the main HOT‐ICU trial.

Trial registration number: ClinicalTrials.gov number, NCT03174002.

Date of registration: June 2, 2017.

Effect of 12 mg vs 6 mg of Dexamethasone on the Number of Days Alive Without Life Support in Adults With COVID-19 and Severe Hypoxemia: The COVID STEROID 2 Randomized Trial

IMPORTANCE

A daily dose with 6 mg of dexamethasone is recommended for up to 10 days in patients with severe and critical COVID-19, but a higher dose may benefit those with more severe disease.

OBJECTIVE

To assess the effects of 12 mg/d vs 6 mg/d of dexamethasone in patients with COVID-19 and severe hypoxemia.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter, randomized clinical trial was conducted between August 2020 and May 2021 at 26 hospitals in Europe and India and included 1000 adults with confirmed COVID-19 requiring at least 10 L/min of oxygen or mechanical ventilation. End of 90-day follow-up was on August 19, 2021.

INTERVENTIONS

Patients were randomized 1:1 to 12 mg/d of intravenous dexamethasone (n = 503) or 6 mg/d of intravenous dexamethasone (n = 497) for up to 10 days.

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of days alive without life support (invasive mechanical ventilation, circulatory support, or kidney replacement therapy) at 28 days and was adjusted for stratification variables. Of the 8 prespecified secondary outcomes, 5 are included in this analysis (the number of days alive without life support at 90 days, the number of days alive out of the hospital at 90 days, mortality at 28 days and at 90 days, and ≥1 serious adverse reactions at 28 days).

RESULTS

Of the 1000 randomized patients, 982 were included (median age, 65 [IQR, 55-73] years; 305 [31%] women) and primary outcome data were available for 971 (491 in the 12 mg of dexamethasone group and 480 in the 6 mg of dexamethasone group). The median number of days alive without life support was 22.0 days (IQR, 6.0-28.0 days) in the 12 mg of dexamethasone group and 20.5 days (IQR, 4.0-28.0 days) in the 6 mg of dexamethasone group (adjusted mean difference, 1.3 days [95% CI, 0-2.6 days]; P = .07). Mortality at 28 days was 27.1% in the 12 mg of dexamethasone group vs 32.3% in the 6 mg of dexamethasone group (adjusted relative risk, 0.86 [99% CI, 0.68-1.08]). Mortality at 90 days was 32.0% in the 12 mg of dexamethasone group vs 37.7% in the 6 mg of dexamethasone group (adjusted relative risk, 0.87 [99% CI, 0.70-1.07]). Serious adverse reactions, including septic shock and invasive fungal infections, occurred in 11.3% in the 12 mg of dexamethasone group vs 13.4% in the 6 mg of dexamethasone group (adjusted relative risk, 0.83 [99% CI, 0.54-1.29]).

CONCLUSIONS AND RELEVANCE

Among patients with COVID-19 and severe hypoxemia, 12 mg/d of dexamethasone compared with 6 mg/d of dexamethasone did not result in statistically significantly more days alive without life support at 28 days. However, the trial may have been underpowered to identify a significant difference.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04509973 and ctri.nic.in Identifier: CTRI/2020/10/028731.

Higher vs lower doses of dexamethasone in patients with COVID-19 and severe hypoxia (COVID STEROID 2) trial: Protocol and statistical analysis plan

Background

The coronavirus disease 2019 (COVID‐19) pandemic has resulted in millions of deaths and overburdened healthcare systems worldwide. Systemic low‐dose corticosteroids have proven clinical benefit in patients with severe COVID‐19. Higher doses of corticosteroids are used in other inflammatory lung diseases and may offer additional clinical benefits in COVID‐19. At present, the balance between benefits and harms of higher vs. lower doses of corticosteroids for patients with COVID‐19 is unclear.

Methods

The COVID STEROID 2 trial is an investigator‐initiated, international, parallel‐grouped, blinded, centrally randomised and stratified clinical trial assessing higher (12 mg) vs. lower (6 mg) doses of dexamethasone for adults with COVID‐19 and severe hypoxia. We plan to enrol 1,000 patients in Denmark, Sweden, Switzerland and India. The primary outcome is days alive without life support (invasive mechanical ventilation, circulatory support or renal replacement therapy) at day 28. Secondary outcomes include serious adverse reactions at day 28; all‐cause mortality at day 28, 90 and 180; days alive without life support at day 90; days alive and out of hospital at day 90; and health‐related quality of life at day 180. The primary outcome will be analysed using the Kryger Jensen and Lange test adjusted for stratification variables and reported as adjusted mean differences and median differences. The full statistical analysis plan is outlined in this protocol.

Discussion

The COVID STEROID 2 trial will provide evidence on the optimal dosing of systemic corticosteroids for COVID‐19 patients with severe hypoxia with important implications for patients, their relatives and society.

Sleep-wake rhythms determined by actigraphy during in-hospital stay following discharge from an intensive care unit

BACKGROUND

Sleep and circadian disturbances play a major role in recovery after critical illness. Ample research has shown sleep to be disturbed during the stay at the intensive care unit (ICU); however, the trajectory of sleep after ICU discharge is sparsely described. The current study aimed to describe the development of the sleep-wake rhythm in subjects discharged from ICU to a hospital ward.

METHODS

Following discharge from the ICU to a general hospital ward, the participants were monitored with an ActiGraph for sleep assessment for 7 days or until hospital discharge or death. Data were analysed for day-to-day change with t-tests and for the whole period with repeated measures analysis.

RESULTS

For the 38 included patients, repeated measures analysis showed no significant improvement in total sleep time and wake time. However, for secondary outcomes, improvements for wake after sleep onset (P = .02) and reduction in the number of naps (P = .03) both in the day-to-day and overall trend analysis were observed.

CONCLUSION

The duration of sleep and wake time did not improve during ward stay. However, sleep became less fragmented and naps during the day declined. Due to the small sample size further, larger trials are needed.

Lower or Higher Oxygenation Targets for Acute Hypoxemic Respiratory Failure

BACKGROUND

Patients with acute hypoxemic respiratory failure in the intensive care unit (ICU) are treated with supplemental oxygen, but the benefits and harms of different oxygenation targets are unclear. We hypothesized that using a lower target for partial pressure of arterial oxygen (Pao₂) would result in lower mortality than using a higher target.

METHODS

In this multicenter trial, we randomly assigned 2928 adult patients who had recently been admitted to the ICU (≤12 hours before randomization) and who were receiving at least 10 liters of oxygen per minute in an open system or had a fraction of inspired oxygen of at least 0.50 in a closed system to receive oxygen therapy targeting a Pao₂ of either 60 mm Hg (lower-oxygenation group) or 90 mm Hg (higher-oxygenation group) for a maximum of 90 days. The primary outcome was death within 90 days.

RESULTS

At 90 days, 618 of 1441 patients (42.9%) in the lower-oxygenation group and 613 of 1447 patients (42.4%) in the higher-oxygenation group had died (adjusted risk ratio, 1.02; 95% confidence interval, 0.94 to 1.11; P = 0.64). At 90 days, there was no significant between-group difference in the percentage of days that patients were alive without life support or in the percentage of days they were alive after hospital discharge. The percentages of patients who had new episodes of shock, myocardial ischemia, ischemic stroke, or intestinal ischemia were similar in the two groups (P = 0.24).

CONCLUSIONS

Among adult patients with acute hypoxemic respiratory failure in the ICU, a lower oxygenation target did not result in lower mortality than a higher target at 90 days. (Funded by the Innovation Fund Denmark and others; HOT-ICU ClinicalTrials.gov number, NCT03174002.).

Health care use before and after intensive care unit admission-A nationwide register-based study

BACKGROUND

The aim of this study was to describe healthcare utilization of patients admitted to ICU before and after ICU admission.

METHODS

Register-based study including adult patients discharged from ICU between January 1st, 2011 and December 31st, 2014. Reference group was a sex- and age-matched population not admitted to an ICU in the study period. Outcomes were hospital admissions, contacts to general practitioner or emergency services and municipality services from 1 year before ICU admission and up to 3 years after.

RESULTS

The study included 82 384 patients and an equal number of reference persons. Of patients with ICU admission, 48% were married (reference group 57%), 48% had elementary school education (reference group 38%) and 18% had a Charlson co-morbidity score of 5+ (4% in reference group). We found that 51% of patients with an ICU admission had been admitted to hospital in the year before ICU admission (reference group 15%) and 97% had a contact to a general practitioner (reference group 89%) in the same period.

CONCLUSIONS

Patients admitted to an ICU had increased use of both primary and secondary health care both before and for years after ICU treatment, even after adjustment for comorbidities and socio-economic factors.

Mortality and HRQoL in ICU patients with delirium: Protocol for 1-year follow-up of AID-ICU trial

BACKGROUND

Intensive care unit (ICU)-acquired delirium is frequent and associated with poor short- and long-term outcomes for patients in ICUs. It therefore constitutes a major healthcare problem. Despite limited evidence, haloperidol is the most frequently used pharmacological intervention against ICU-acquired delirium. Agents intervening against Delirium in the ICU (AID-ICU) is an international, multicentre, randomised, blinded, placebo-controlled trial investigates benefits and harms of treatment with haloperidol in patients with ICU-acquired delirium. The current pre-planned one-year follow-up study of the AID-ICU trial population aims to explore the effects of haloperidol on one-year mortality and health related quality of life (HRQoL).

METHODS

The AID-ICU trial will include 1000 participants. One-year mortality will be obtained from the trial sites; we will validate the vital status of Danish participants using the Danish National Health Data Registers. Mortality will be analysed by Cox-regression and visualized by Kaplan-Meier curves tested for significance using the log-rank test. We will obtain HRQoL data using the EQ-5D instrument. HRQoL analysis will be performed using a general linear model adjusted for stratification variables. Deceased participants will be designated the worst possible value.

RESULTS

We expect to publish results of this study in 2022.

CONCLUSION

We expect that this one-year follow-up study of participants with ICU-acquired delirium allocated to haloperidol vs. placebo will provide important information on the long-term consequences of delirium including the effects of haloperidol. We expect that our results will improve the care of this vulnerable patient group.

The Agents Intervening against Delirium in the Intensive Care Unit Trial (AID-ICU trial): A detailed statistical analysis plan

BACKGROUND

The AID-ICU trial aims to assess the benefits and harms of haloperidol for the treatment of delirium in acutely admitted, adult intensive care unit (ICU) patients. This paper describes the detailed statistical analysis plan for the primary publication of results from the AID-ICU trial.

METHODS

The AID-ICU trial is an investigator-initiated, pragmatic, international, multicentre, randomized, blinded, parallel-group trial allocating 1000 adult ICU patients with manifest delirium 1:1 to haloperidol or placebo. The primary outcome measure is days alive and out of hospital within 90 days post-randomization. Secondary outcome measures are days alive without delirium or coma, serious adverse reactions (SARs) to haloperidol, use of escape medicine, days alive without mechanical ventilation, and mortality, health-related quality-of-life measures and cognitive function 1-year post-randomization. Statistical analysis will be conducted in accordance with the current pre-specified statistical analysis plan. One formal interim analysis will be performed. The primary outcome will be adjusted for stratification variables (site and delirium motor subtype) and compared between treatment groups using a likelihood ratio test described by Jensen et al A secondary analysis will be conducted with additional adjustment of the primary outcome for prognostic variables at baseline. The primary conclusion of the trial will be based on the intention-to-treat analysis of the primary outcome adjusted for stratification variables.

CONCLUSION

The AID-ICU trial will provide important, high-quality data on the benefits and harms of treatment with haloperidol in acutely admitted, adult patients with manifest delirium in the ICU.

Healthcare providers' knowledge and handling of impairments after intensive unit treatment: A questionnaire survey

BACKGROUND

Numerous patients experience long-term impairments after discharge from the intensive care unit (ICU), including physical, psychological and cognitive deficiencies. This study aims to investigate the knowledge and handling of post-intensive care impairments among Danish doctors and nurses in the medical and surgical wards.

METHODS

An electronic questionnaire survey was distributed to consultants and development nurses, head nurses and assistant head nurses at departments of abdominal surgery and internal medicine of hospitals with an ICU in the Region Zealand of Denmark.

RESULTS

We invited 350 employees to participate, 48% responded. Most participants, 82.8% nurses and 86.6% doctors, reported their knowledge of in-hospital needs of the ICU patients to be average or higher. Sixty per cent of doctors reported having average or higher knowledge of the patients' post-discharge needs. More than half the doctors (60.2%) reported that they "Rarely" or "Never" addressed possible ICU-related impairments in the discharge summary. During hospital admission, 22.9% replied "No screening performed" for physical impairment, while the rates for psychological and cognitive impairments were 70.7% and 57.3%, respectively. Most respondents believed that doctors (92.8%) and nurses (92.1%) in the ward and ICU doctors (89.4%) play an important role in detecting ICU-related impairments; 63.8% felt that general practitioners play a key role.

CONCLUSION

Doctors and nurses generally reported having average or higher knowledge of ICU patients' in-hospital needs, but few screened systematically for ICU-related impairments. Most respondents believed that detecting these problems is a shared responsibility between professionals in the primary and, especially, the secondary healthcare sector.

Recovery after acute illness after hospital discharge - a prospective cohort study

BACKGROUND

Long-term outcomes after acute medical and surgical illness are largely unknown.

AIM

To describe cognitive and physical function, health-related quality of life and risk of anxiety and depression after acute illness.

DESIGN

Prospective cohort study.

METHODS

Home visit at three and twelve months measuring: Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Chelsea Critical Care Physical Assessment tool, Short Form Health Survey, Hospital Anxiety and Depression Scale and Trail Making Test.

RESULTS

Of 101 included patients, 60 were visited at three and 36 at twelve months. The RBANS value was 84 (69-96) at three months and 88 (69-101) at twelve months.

CONCLUSIONS

We found a moderately reduced cognitive function three and twelve months after acute illness.

Agents intervening against delirium in the intensive care unit (AID-ICU) - Protocol for a randomised placebo-controlled trial of haloperidol in patients with delirium in the ICU

BACKGROUND

Delirium among patients in the intensive care unit (ICU) is a common condition associated with increased morbidity and mortality. Haloperidol is the most frequently used pharmacologic intervention, but its use is not supported by firm evidence. Therefore, we are conducting Agents Intervening against Delirium in the Intensive Care Unit (AID-ICU) trial to assess the benefits and harms of haloperidol for the treatment of ICU-acquired delirium.

METHODS

AID-ICU is an investigator-initiated, pragmatic, international, randomised, blinded, parallel-group, trial allocating adult ICU patients with manifest delirium 1:1 to haloperidol or placebo. Trial participants will receive intravenous 2.5 mg haloperidol three times daily or matching placebo (isotonic saline 0.9%) if they are delirious. If needed, a maximum of 20 mg/daily haloperidol/placebo is given. An escape protocol, not including haloperidol, is part of the trial protocol. The primary outcome is days alive out of the hospital within 90 days post-randomisation. Secondary outcomes are number of days without delirium or coma, serious adverse reactions to haloperidol, usage of escape medication, number of days alive without mechanical ventilation; mortality, health-related quality-of-life and cognitive function at 1-year follow-up. A sample size of 1000 patients is required to detect a 7-day improvement or worsening of the mean days alive out of the hospital, type 1 error risk of 5% and power 90%.

PERSPECTIVE

The AID-ICU trial is based on gold standard methodology applied to a large sample of clinically representative patients and will provide pivotal high-quality data on the benefits and harms of haloperidol for the treatment ICU-acquired delirium.

Physical function and actigraphy in intensive care survivors-A prospective 3-month follow-up cohort study

BACKGROUND

Impaired physical function after intensive care unit (ICU) stay is common. We aimed to study the association between activity levels in the ward after discharge from ICU and physical function at 3-month follow-up.

METHODS

Prospective cohort study of adult patients admitted to the ICU for more than 24 hours. Patients wore an accelerometer for up to 7 days at the ward. At discharge from ICU and at 3-month follow-up, patients were tested with the Chelsea Critical Care Physical Assessment Tool (CPAx).

RESULTS

We screened 66 consecutive, eligible patients; 41 completed actigraphy and 19 patients were visited at 3 months. The median CPAx increased from 31 (IQR 23-41) at discharge from ICU to 47 (IQR 44-49) at follow-up (P < 0.0001). Mean daily activity for the first week was correlated with CPAx at ICU discharge (R²  = 0.14, P = 0.017; all 41 patients). For the 19 visited patients, we found no significant correlation for activity levels with CPAx at ICU discharge (R²  = 0.12, P = 0.14) nor at visit (R²  = 0.2, P = 0.058).

CONCLUSION

We found improved physical function for most patients 3 months after ICU treatment. Activity levels for 1 week after ICU discharge at the ward were not associated with better physical function at 3-month follow-up.

Randomized multicentre feasibility trial of intermediate care versus standard ward care after emergency abdominal surgery (InCare trial)

Background

Emergency abdominal surgery carries a considerable risk of death and postoperative complications. Early detection and timely management of complications may reduce mortality. The aim was to evaluate the effect and feasibility of intermediate care compared with standard ward care in patients who had emergency abdominal surgery.

Methods

This was a randomized clinical trial carried out in seven Danish hospitals. Eligible for inclusion were patients with an Acute Physiology And Chronic Health Evaluation (APACHE) II score of at least 10 who were ready to be transferred to the surgical ward within 24 h of emergency abdominal surgery. Participants were randomized to either intermediate care or standard surgical ward care after surgery. The primary outcome was 30-day mortality.

Results

In total, 286 patients were included in the modified intention-to-treat analysis. The trial was terminated after the interim analysis owing to slow recruitment and a lower than expected mortality rate. Eleven (7·6 per cent) of 144 patients assigned to intermediate care and 12 (8·5 per cent) of 142 patients assigned to ward care died within 30 days of surgery (odds ratio 0·91, 95 per cent c.i. 0·38 to 2·16; P = 0·828). Thirty (20·8 per cent) of 144 patients assigned to intermediate care and 37 (26·1 per cent) of 142 assigned to ward care died within the total observation period (hazard ratio 0·78, 95 per cent c.i. 0·48 to 1·26; P = 0·310).

Conclusion

Postoperative intermediate care had no statistically significant effect on 30-day mortality after emergency abdominal surgery, nor any effect on secondary outcomes. The trial was stopped prematurely owing to slow recruitment and a much lower than expected mortality rate among the enrolled patients. Registration number: NCT01209663 (http://www.clinicaltrials.gov).

Red blood cell transfusion in septic shock - clinical characteristics and outcome of unselected patients in a prospective, multicentre cohort

Background

Treating anaemia with red blood cell (RBC) transfusion is frequent, but controversial, in patients with septic shock. Therefore we assessed characteristics and outcome associated with RBC transfusion in this group of high risk patients.

Methods

We did a prospective cohort study at 7 general intensive care units (ICUs) including all adult patients with septic shock in a 5-month period.

Results

Ninety-five of the 213 included patients (45%) received median 3 (interquartile range 2–5) RBC units during shock. The median pre-transfusion haemoglobin level was 8.1 (7.4–8.9) g/dl and independent of shock day and bleeding. Patients with cardiovascular disease were transfused at higher haemoglobin levels. Transfused patients had higher Simplified Acute Physiology Score (SAPS) II (56 (45-69) vs. 48 (37-61), p = 0.0005), more bleeding episodes, lower haemoglobin levels days 1 to 5, higher Sepsis-related Organ Failure Assessment (SOFA) scores (days 1 and 5), more days in shock (5 (3-10) vs. 2 (2-4), p = 0.0001), more days in ICU (10 (4-19) vs. 4 (2-8), p = 0.0001) and higher 90-day mortality (66 vs. 43%, p = 0.001). The latter association was lost after adjustment for admission category and SAPS II and SOFA-score on day 1.

Conclusions

The decision to transfuse patients with septic shock was likely affected by disease severity and bleeding, but haemoglobin level was the only measure that consistently differed between transfused and non-transfused patients.

Transfusion requirements in septic shock (TRISS) trial - comparing the effects and safety of liberal versus restrictive red blood cell transfusion in septic shock patients in the ICU: protocol for a randomised controlled trial

BACKGROUND

Transfusion of red blood cells (RBC) is recommended in septic shock and the majority of these patients receive RBC transfusion in the intensive care unit (ICU). However, benefit and harm of RBCs have not been established in this group of high-risk patients.

METHODS/DESIGN

The Transfusion Requirements in Septic Shock (TRISS) trial is a multicenter trial with assessor-blinded outcome assessment, randomising 1,000 patients with septic shock in 30 Scandinavian ICUs to receive transfusion with pre-storage leuko-depleted RBC suspended in saline-adenine-glucose and mannitol (SAGM) at haemoglobin level (Hb) of 7 g/dl or 9 g/dl, stratified by the presence of haematological malignancy and centre. The primary outcome measure is 90-day mortality. Secondary outcome measures are organ failure, ischaemic events, severe adverse reactions (SARs: anaphylactic reaction, acute haemolytic reaction and transfusion-related circulatory overload, and acute lung injury) and mortality at 28 days, 6 months and 1 year.The sample size will enable us to detect a 9% absolute difference in 90-day mortality assuming a 45% event rate with a type 1 error rate of 5% and power of 80%. An interim analysis will be performed after 500 patients, and the Data Monitoring and Safety Committee will recommend the trial be stopped if a group difference in 90-day mortality with P ≤0.001 is present at this point.

DISCUSSION

The TRISS trial may bridge the gap between clinical practice and the lack of efficacy and safety data on RBC transfusion in septic shock patients. The effect of restrictive versus liberal RBC transfusion strategy on mortality, organ failure, ischaemic events and SARs will be evaluated.

Hydroxyethyl starch 130/0.42 versus Ringer's acetate in severe sepsis

BACKGROUND

Hydroxyethyl starch (HES) [corrected] is widely used for fluid resuscitation in intensive care units (ICUs), but its safety and efficacy have not been established in patients with severe sepsis.

METHODS

In this multicenter, parallel-group, blinded trial, we randomly assigned patients with severe sepsis to fluid resuscitation in the ICU with either 6% HES 130/0.42 (Tetraspan) or Ringer's acetate at a dose of up to 33 ml per kilogram of ideal body weight per day. The primary outcome measure was either death or end-stage kidney failure (dependence on dialysis) at 90 days after randomization.

RESULTS

Of the 804 patients who underwent randomization, 798 were included in the modified intention-to-treat population. The two intervention groups had similar baseline characteristics. At 90 days after randomization, 201 of 398 patients (51%) assigned to HES 130/0.42 had died, as compared with 172 of 400 patients (43%) assigned to Ringer's acetate (relative risk, 1.17; 95% confidence interval [CI], 1.01 to 1.36; P=0.03); 1 patient in each group had end-stage kidney failure. In the 90-day period, 87 patients (22%) assigned to HES 130/0.42 were treated with renal-replacement therapy versus 65 patients (16%) assigned to Ringer's acetate (relative risk, 1.35; 95% CI, 1.01 to 1.80; P=0.04), and 38 patients (10%) and 25 patients (6%), respectively, had severe bleeding (relative risk, 1.52; 95% CI, 0.94 to 2.48; P=0.09). The results were supported by multivariate analyses, with adjustment for known risk factors for death or acute kidney injury at baseline.

CONCLUSIONS

Patients with severe sepsis assigned to fluid resuscitation with HES 130/0.42 had an increased risk of death at day 90 and were more likely to require renal-replacement therapy, as compared with those receiving Ringer's acetate. (Funded by the Danish Research Council and others; 6S ClinicalTrials.gov number, NCT00962156.).

Identification of cytotoxic T cell epitopes within Epstein-Barr virus (EBV) oncogene latent membrane protein 1 (LMP1): evidence for HLA A2 supertype-restricted immune recognition of EBV-infected cells by LMP1-specific cytotoxic T lymphocytes

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) and latent membrane proteins (LMP) are the only antigens consistently expressed in malignancies such as nasopharyngeal carcinoma (NPC) and Hodgkin's disease (HD). Since EBNA1 is not recognized by EBV-specific cytotoxic T lymphocytes (CTL), there is increasing interest in the identification of the potential target epitopes within LMP1. Although LMP1-specific CTL have been isolated from seropositive individuals, earlier attempts to identify the peptide epitopes recognized by these T cells have been unsuccessful. In the present report we used a novel protocol to identify CTL epitopes within LMP1 which can be recognized by both polyclonal and clonal CTL. Firstly, a computer-based program was employed to identify the potential HLA-binding peptides within LMP1. Polyclonal CD8+ CTL were then isolated from seropositive donors that recognized the peptide epitopes YLLEMLWRL and YLQQNWWTL from LMP1 in association with HLA A2. Limiting dilution analysis of the memory CTL response revealed that the LMP1-specific CTL response constitutes a minor component of the CTL response in healthy virus carriers. Interestingly, analysis of YLLEMLWRL-specific CTL revealed that these CTL were able to lyse EBV-infected B cells expressing different HLA A2 supertype alleles including A*0201, A*0202, A*0203, A*0204, A*0206, A*6802 and A*6901. These data strongly support the notion that HLA class I supertype-restricted CTL may be of significant use in the development of peptide-based immunotherapeutics against EBV-associated malignancies in different ethnic populations.

Class I processing-defective Burkitt's lymphoma cells are recognized efficiently by CD4+ EBV-specific CTLs

In the present study, we have isolated CD4+ CTLs that recognize an epitope from EBV nuclear Ag 2 in association with two different HLA-DQ Ags, DQA1*0501/DQB1*0201 (DQ2) or DQA1*0501/DQB1*0301 (DQ7). Both the HLA-DQ2 and HLA-DQ7 alleles displayed a similar efficiency in the endogenous and exogenous presentation of this epitope. Since earlier studies have shown that the EBV-associated malignancy, Burkitt's lymphoma (BL), escapes class I-restricted immune recognition by down-regulating the expression of peptide transporter genes, we have explored the possibility that these tumor cells can process class II-restricted CTL epitopes. The data presented in this study clearly demonstrate that BL cells were recognized efficiently by CD4+, MHC class II-restricted EBV-specific CTLs following infection with recombinant vaccinia encoding EBV nuclear Ag 2. Analysis of surface MHC class II expression on BL cells revealed high levels of HLA-DR and HLA-DQ molecules, and most of these molecules were negative for the invariant chain peptide, referred to as CLIP. Moreover, these tumor cells also showed normal levels of HLA-DMB gene expression, which has been shown previously to be an essential component of the class II processing pathway. The present finding of efficient processing function through the class II pathway in BL cells provides a novel mechanism for immune targeting of EBV-positive malignancies.

Class I processing-defective Burkitt's lymphoma cells are recognized efficiently by CD4+ EBV-specific CTLs

In the present study, we have isolated CD4+ CTLs that recognize an epitope from EBV nuclear Ag 2 in association with two different HLA-DQ Ags, DQA1*0501/DQB1*0201 (DQ2) or DQA1*0501/DQB1*0301 (DQ7). Both the HLA-DQ2 and HLA-DQ7 alleles displayed a similar efficiency in the endogenous and exogenous presentation of this epitope. Since earlier studies have shown that the EBV-associated malignancy, Burkitt's lymphoma (BL), escapes class I-restricted immune recognition by down-regulating the expression of peptide transporter genes, we have explored the possibility that these tumor cells can process class II-restricted CTL epitopes. The data presented in this study clearly demonstrate that BL cells were recognized efficiently by CD4+, MHC class II-restricted EBV-specific CTLs following infection with recombinant vaccinia encoding EBV nuclear Ag 2. Analysis of surface MHC class II expression on BL cells revealed high levels of HLA-DR and HLA-DQ molecules, and most of these molecules were negative for the invariant chain peptide, referred to as CLIP. Moreover, these tumor cells also showed normal levels of HLA-DMB gene expression, which has been shown previously to be an essential component of the class II processing pathway. The present finding of efficient processing function through the class II pathway in BL cells provides a novel mechanism for immune targeting of EBV-positive malignancies.

Cytotoxic T-lymphocyte clones specific for an immunodominant epitope display discerning antagonistic response to naturally occurring Epstein-Barr virus variants

In the present study we have identified Epstein-Barr virus isolates which encode variant sequences within an HLA B35-restricted immunodominant cytotoxic T-lymphocyte (CTL) epitope that act as natural antagonists and can inhibit CTL activity on the wild-type epitope. This effect can be demonstrated if the wild-type epitope is presented as a synthetic peptide or when processed from a full-length Epstein-Barr virus protein expressed by recombinant vaccinia constructs. However, this antagonistic effect was only selectively seen with some CTL clones, while a strong agonistic effect was evident for other clones in the presence of the same variant peptide. The data presented in this study strongly suggest that it is unlikely that the variant viruses can completely antagonize a virus-specific CTL response by this mechanism since the host immune response is capable of generating CTLs expressing a diverse array of T-cell receptors. Moreover, many of these CTLs can recognize the variant sequences as efficiently as wild-type epitope.

Unusually high frequency of Epstein-Barr virus genetic variants in Papua New Guinea that can escape cytotoxic T-cell recognition: implications for virus evolution

Cytotoxic T lymphocytes (CTLs) which recognize viral antigens in association with human leukocyte antigens (HLAs) play an important role in controlling persistent virus infections. These viruses use several mechanisms to evade the immune response, including mutations that affect either T-cell receptor recognition or binding of viral epitopes to the HLA. It has recently been proposed that the distribution of HLA frequencies and the specific CTL response may influence the long-term evolution of Epstein-Barr virus (EBV) by selecting variants which lack immunodominant CTL epitopes. To test this hypothesis, we have studied EBV isolates from two genetically distinct Papua New Guinea (PNG) populations, residing in coastal and highland regions, for polymorphism within seven viral CTL epitope sequences restricted through several class I HLAs. Surprisingly, all EBV isolates analyzed displayed identical amino acid substitutions within HLA A11-, B35- and B8-restricted CTL epitope sequences which completely abrogated CTL recognition and binding of synthetic peptides to HLA molecules. Furthermore, these substitutions revealed no correlation with the contemporary distribution of HLAs in the different PNG populations, which argues for a minimal influence of immune pressure. The sequence homology between EBV isolates from coastal and highland PNG suggests that the virus may have had a single origin and, more importantly, that these isolates are genetically distinct from those present in a Caucasian population.