Key result
The initiation of a trial of a prescribed lower mean arterial pressure target was not associated with a change in mean arterial pressure compared to pre-trial usual care (72.4 vs 72.5 mmHg, p=0.76).
Why the study?
If usual care processes evolve to resemble the intervention during an unblinded trial, differences between intervention and control groups may narrow.
Does the initiation of a trial comparing a lower mean arterial pressure target to usual care change the mean arterial pressure achieved in critically ill patients on vasopressors?
Observational (n=429)
Yes
Does the initiation of a trial comparing a lower mean arterial pressure target to usual care change the mean arterial pressure achieved in critically ill patients on vasopressors?
Answers are grounded in this paper and cite their sources.
The initiation of a trial comparing a lower mean arterial pressure target to usual care did not alter the mean arterial pressure achieved in usual care, suggesting stability in clinical practice over time.
BACKGROUND: In randomized clinical controlled trials, the choice of usual care as the comparator may be associated with better clinician uptake of the study protocol and lead to more generalizable results. However, if care processes evolve to resemble the intervention during the course of a trial, differences between the intervention group and usual care control group may narrow. We evaluated the effect on mean arterial pressure of an unblinded trial comparing a lower mean arterial pressure target to reduce vasopressor exposure, vs. a clinician-selected mean arterial pressure target, in critically ill patients at least 65 years old. METHODS: For this multicenter observational study using data collected both prospectively and retrospectively, patients were recruited from five of the seven trial sites. We compared the mean arterial pressure of patients receiving vasopressors, who met or would have met trial eligibility criteria, from two periods: [1] at least 1 month before the trial started, and [2] during the trial period and randomized to usual care, or not enrolled in the trial. RESULTS: We included 200 patients treated before and 229 after trial initiation. There were no differences in age (mean 74.5 vs. 75.2 years; p = 0.28), baseline Acute Physiology and Chronic Health Evaluation II score (median 26 vs. 26; p = 0.47) or history of chronic hypertension (n = 126 [63.0%] vs. n = 153 [66.8%]; p = 0.41). Mean of the mean arterial pressure was similar between the two periods (72.5 vs. 72.4 mmHg; p = 0.76). CONCLUSIONS: The initiation of a trial of a prescribed lower mean arterial pressure target, compared to a usual clinician-selected target, was not associated with a change in mean arterial pressure, reflecting stability in the net effect of usual clinician practices over time. Comparing prior and concurrent control groups may alleviate concerns regarding drift in usual practices over the course of a trial or permit quantification of any change.
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Masse et al. (2022) conducted an observational in Vasodilatory hypotension (n=429). Initiation of a clinical trial (OVATION-65) vs. Pre-trial period (usual care) was evaluated on Mean arterial pressure (MAP) while receiving vasopressors (p=0.76). The initiation of a trial of a prescribed lower mean arterial pressure target was not associated with a change in mean arterial pressure compared to pre-trial usual care (72.4 vs 72.5 mmHg, p=0.76).
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