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. 2021 Feb;25(14):1–90. doi: 10.3310/hta25140

Reduced exposure to vasopressors through permissive hypotension to reduce mortality in critically ill people aged 65 and over: the 65 RCT.

Paul R Mouncey, Alvin Richards-Belle, Karen Thomas, David A Harrison, M Zia Sadique, Richard D Grieve, Julie Camsooksai, Robert Darnell, Anthony C Gordon, Doreen Henry, Nicholas Hudson, Alexina J Mason, Michelle Saull, Chris Whitman, J Duncan Young, François Lamontagne, Kathryn M Rowan; 65 trial investigators
PMCID: PMC7957458  PMID: 33648623

Abstract

BACKGROUND

Vasopressors are administered to critical care patients to avoid hypotension, which is associated with myocardial injury, kidney injury and death. However, they work by causing vasoconstriction, which may reduce blood flow and cause other adverse effects. A mean arterial pressure target typically guides administration. An individual patient data meta-analysis (Lamontagne F, Day AG, Meade MO, Cook DJ, Guyatt GH, Hylands M, et al. Pooled analysis of higher versus lower blood pressure targets for vasopressor therapy septic and vasodilatory shock. Intensive Care Med 2018;44:12-21) suggested that greater exposure, through higher mean arterial pressure targets, may increase risk of death in older patients.

OBJECTIVE

To estimate the clinical effectiveness and cost-effectiveness of reduced vasopressor exposure through permissive hypotension (i.e. a lower mean arterial pressure target of 60-65 mmHg) in older critically ill patients.

DESIGN

A pragmatic, randomised clinical trial with integrated economic evaluation.

SETTING

Sixty-five NHS adult general critical care units.

PARTICIPANTS

Critically ill patients aged ≥ 65 years receiving vasopressors for vasodilatory hypotension.

INTERVENTIONS

Intervention - permissive hypotension (i.e. a mean arterial pressure target of 60-65 mmHg). Control (usual care) - a mean arterial pressure target at the treating clinician's discretion.

MAIN OUTCOME MEASURES

The primary clinical outcome was 90-day all-cause mortality. The primary cost-effectiveness outcome was 90-day incremental net monetary benefit. Secondary outcomes included receipt and duration of advanced respiratory and renal support, mortality at critical care and acute hospital discharge, and questionnaire assessment of cognitive decline and health-related quality of life at 90 days and 1 year.

RESULTS

Of 2600 patients randomised, 2463 (permissive hypotension, n = 1221; usual care, n = 1242) were analysed for the primary clinical outcome. Permissive hypotension resulted in lower exposure to vasopressors than usual care [mean duration 46.0 vs. 55.9 hours, difference -9.9 hours (95% confidence interval -14.3 to -5.5 hours); total noradrenaline-equivalent dose 31.5 mg vs. 44.3 mg, difference -12.8 mg (95% CI -18.0 mg to -17.6 mg)]. By 90 days, 500 (41.0%) patients in the permissive hypotension group and 544 (43.8%) patients in the usual-care group had died (absolute risk difference -2.85%, 95% confidence interval -6.75% to 1.05%; p = 0.154). Adjustment for prespecified baseline variables resulted in an odds ratio for 90-day mortality of 0.82 (95% confidence interval 0.68 to 0.98) favouring permissive hypotension. There were no significant differences in prespecified secondary outcomes or subgroups; however, patients with chronic hypertension showed a mortality difference favourable to permissive hypotension. At 90 days, permissive hypotension showed similar costs to usual care. However, with higher incremental life-years and quality-adjusted life-years in the permissive hypotension group, the incremental net monetary benefit was positive, but with high statistical uncertainty (£378, 95% confidence interval -£1347 to £2103).

LIMITATIONS

The intervention was unblinded, with risk of bias minimised through central allocation concealment and a primary outcome not subject to observer bias. The control group event rate was higher than anticipated.

CONCLUSIONS

In critically ill patients aged ≥ 65 years receiving vasopressors for vasodilatory hypotension, permissive hypotension did not significantly reduce 90-day mortality compared with usual care. The absolute treatment effect on 90-day mortality, based on 95% confidence intervals, was between a 6.8-percentage reduction and a 1.1-percentage increase in mortality.

FUTURE WORK

Future work should (1) update the individual patient data meta-analysis, (2) explore approaches for evaluating heterogeneity of treatment effect and (3) explore 65 trial conduct, including use of deferred consent, to inform future trials.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN10580502.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 14. See the NIHR Journals Library website for further project information.

Plain language summary

Low blood pressure is common in patients in intensive care. It is associated with a high risk of death. It can be treated with drugs called vasopressors. These drugs raise blood pressure, but also come with risks and side effects. Usually, a blood pressure target is used to guide how much of the drugs to give to patients. Two previous clinical trials suggested that using a lower blood pressure target (and therefore giving less of the drugs) might reduce the number of deaths among older patients. However, although these results were promising, more research was needed to find out if they were correct. The 65 trial was carried out to test if using a lower blood pressure target really did improve outcomes for older patients. The trial also looked at whether or not it would provide value for money for the NHS. A total of 2600 patients aged ≥ 65 years who had low blood pressure in intensive care joined the trial. Half were randomly assigned to the new lower blood pressure target (less drugs). The other half were assigned to usual care (control group). As we had hoped, patients in the low blood pressure target group received less vasopressor drugs than the usual-care group. After 90 days, 41% of patients in the new low blood pressure target group had died, compared with 44% in the usual-care group. Although fewer patients died in the low blood pressure target group, the difference was small and may have occurred by chance. On average, the new target saved a small amount of money for the NHS. Although we could not prove that use of a lower blood pressure target saves lives for older patients in intensive care, our trial suggests that it might. Receiving less vasopressor drugs appeared safe for patients.

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