Post hoc analysis can’t rule out all confounders
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General anesthesia linked to worsened stroke outcomes

NASHVILLE, TENN. – When acute ischemic stroke patients undergo an emergency endovascular procedure is it best done with general anesthesia or nongeneral anesthesia?

A post hoc analysis of data collected by a Dutch randomized, controlled trial of intra-arterial therapy suggested that nongeneral anesthesia was associated with substantially better patient outcomes, and the findings convinced the Dutch investigators who ran the study to stick with nongeneral anesthesia as their default approach.

In MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) (N. Engl. J. Med. 2015;372:11-20), 216 acute ischemic stroke patients underwent intra-arterial treatment following randomization. Among these patients, 79 were treated with general anesthesia and 137 with nongeneral anesthesia. The anesthesia choice was made on a case-by-case basis by each participating interventionalist.

The study’s primary endpoint – 90-day status rated as a good function based on a modified Rankin sale score of 0-2 – occurred in 38% of the intra-arterial patients treated with nongeneral anesthesia, 23% of the intra-arterial patients treated with general anesthesia, and 19% among the control patients who received standard treatment without intra-arterial intervention.

Dr. Olvert A. Berkhemer
Mitchel L. Zoler/Frontline Medical News
Dr. Olvert A. Berkhemer

“The effect on outcome that we found with intra-arterial treatment in MR CLEAN was not observed in the subgroup of patients treated with general anesthesia,” said Dr. Olvert A. Berkhemer at the International Stroke Conference. The analysis also showed that patients in the general and nongeneral anesthesia subgroups had similar stroke severity as measured by their National Institutes of Health Stroke Scale score, said Dr. Berkhemer, a researcher at the Academic Medical Center in Amsterdam.

But U.S. stroke specialists who heard the report cautioned that unidentified confounders might explain the results, and they also expressed skepticism that the Dutch observations would deter U.S. interventionalists from continuing to use general anesthesia when they perform endovascular procedures.

“The big concern [about this analysis] is that there may have been some things about the general anesthesia patients that they did not account for. I suspect there is a huge bias, that general anesthesia patients were sicker,” said Dr. Bruce Ovbiagele, professor and chief of neurology at the Medical University of South Carolina in Charleston. “At my institution they have used nongeneral anesthesia, but I have been at other places where they usually use general anesthesia; it is variable,” Dr. Ovbiagele added.

Dr. Bruce I. Ovbiagele
Mitchel L. Zoler/Frontline Medical News
Dr. Bruce I. Ovbiagele

Dr. Berkhemer’s analysis also showed that general anesthesia linked with a delayed start to treatment, but without resulting in a significant difference in time to reperfusion. He noted that “sometimes you cannot do the procedure without general anesthesia,” and in MR CLEAN 6 of the 137 intra-arterial patients who started with nongeneral anesthesia eventually received general anesthesia because of discomfort and pain, Dr. Berkhemer said at the conference, sponsored by the American Heart Association.

He speculated that patients who did not receive general anesthesia did better because they did not undergo acute episodes of reduced blood pressure caused by the hypotensive effect of general anesthesia.

Dr. Diederik W.J. .Dippel
Mitchel L. Zoler/Frontline Medical News
Dr. Diederik W.J. .Dippel

The findings reinforced the approach already used in most of the Dutch centers that participated in MR CLEAN, where nongeneral anesthesia is preferred when possible. “In our center we always use nongeneral anesthesia, we are happy with that and we are not going to change,” said Dr. Diederik W.J. Dippel, lead investigator of MR CLEAN and professor of neurology at Erasmus University Medical Center in Rotterdam, The Netherlands. This prejudice against general anesthesia would make it hard to run a trial in The Netherlands that matched the two anesthesia approaches against each other, Dr. Dippel added.

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

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Results from prior analyses had also shown better outcomes of acute ischemic stroke patients undergoing endovascular intervention when they avoided general anesthesia. A notable feature of Dr. Berkhemer’s analysis was that the stroke severity levels were well balanced between the patients who received general anesthesia and those who did not. But many other factors aside from stroke severity can affect whether or not a patient receives general anesthesia.

Dr. Larry B. Goldstein

Although the outcome differences seen in this analysis were striking, many factors could have contributed. Patients received different drugs, patients may have had widely divergent clinical states despite their similar stroke severity, and the people performing the procedures were different. The many variables make it very hard to pinpoint the cause of the different outcomes.

At my institution, Duke, the interventionalists who work on acute ischemic stroke patients almost exclusively use general anesthesia. That’s because of their concern about how patients will act during a very delicate procedure. For example, stroke patients can have an aphasia that makes it hard for them to respond to requests to do something specific during the procedure. I am very skeptical that my colleagues will decide to switch to using no general anesthesia based on the results of this new analysis.

I agree with the Dutch investigators that a randomized, controlled trial of general anesthesia or no general anesthesia would be very hard to perform because individual interventionalists would need to believe there is equipoise between the two anesthesia approaches. Most interventionalists right now probably believe the approach they have always used remains best and so would be unwilling to participate in a randomized controlled trial.

Dr. Larry B. Goldstein is professor of neurology and chief of the stroke center at Duke University in Durham, N.C. He had no relevant disclosures. He made these comments in an interview.

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Results from prior analyses had also shown better outcomes of acute ischemic stroke patients undergoing endovascular intervention when they avoided general anesthesia. A notable feature of Dr. Berkhemer’s analysis was that the stroke severity levels were well balanced between the patients who received general anesthesia and those who did not. But many other factors aside from stroke severity can affect whether or not a patient receives general anesthesia.

Dr. Larry B. Goldstein

Although the outcome differences seen in this analysis were striking, many factors could have contributed. Patients received different drugs, patients may have had widely divergent clinical states despite their similar stroke severity, and the people performing the procedures were different. The many variables make it very hard to pinpoint the cause of the different outcomes.

At my institution, Duke, the interventionalists who work on acute ischemic stroke patients almost exclusively use general anesthesia. That’s because of their concern about how patients will act during a very delicate procedure. For example, stroke patients can have an aphasia that makes it hard for them to respond to requests to do something specific during the procedure. I am very skeptical that my colleagues will decide to switch to using no general anesthesia based on the results of this new analysis.

I agree with the Dutch investigators that a randomized, controlled trial of general anesthesia or no general anesthesia would be very hard to perform because individual interventionalists would need to believe there is equipoise between the two anesthesia approaches. Most interventionalists right now probably believe the approach they have always used remains best and so would be unwilling to participate in a randomized controlled trial.

Dr. Larry B. Goldstein is professor of neurology and chief of the stroke center at Duke University in Durham, N.C. He had no relevant disclosures. He made these comments in an interview.

Body

Results from prior analyses had also shown better outcomes of acute ischemic stroke patients undergoing endovascular intervention when they avoided general anesthesia. A notable feature of Dr. Berkhemer’s analysis was that the stroke severity levels were well balanced between the patients who received general anesthesia and those who did not. But many other factors aside from stroke severity can affect whether or not a patient receives general anesthesia.

Dr. Larry B. Goldstein

Although the outcome differences seen in this analysis were striking, many factors could have contributed. Patients received different drugs, patients may have had widely divergent clinical states despite their similar stroke severity, and the people performing the procedures were different. The many variables make it very hard to pinpoint the cause of the different outcomes.

At my institution, Duke, the interventionalists who work on acute ischemic stroke patients almost exclusively use general anesthesia. That’s because of their concern about how patients will act during a very delicate procedure. For example, stroke patients can have an aphasia that makes it hard for them to respond to requests to do something specific during the procedure. I am very skeptical that my colleagues will decide to switch to using no general anesthesia based on the results of this new analysis.

I agree with the Dutch investigators that a randomized, controlled trial of general anesthesia or no general anesthesia would be very hard to perform because individual interventionalists would need to believe there is equipoise between the two anesthesia approaches. Most interventionalists right now probably believe the approach they have always used remains best and so would be unwilling to participate in a randomized controlled trial.

Dr. Larry B. Goldstein is professor of neurology and chief of the stroke center at Duke University in Durham, N.C. He had no relevant disclosures. He made these comments in an interview.

Title
Post hoc analysis can’t rule out all confounders
Post hoc analysis can’t rule out all confounders

NASHVILLE, TENN. – When acute ischemic stroke patients undergo an emergency endovascular procedure is it best done with general anesthesia or nongeneral anesthesia?

A post hoc analysis of data collected by a Dutch randomized, controlled trial of intra-arterial therapy suggested that nongeneral anesthesia was associated with substantially better patient outcomes, and the findings convinced the Dutch investigators who ran the study to stick with nongeneral anesthesia as their default approach.

In MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) (N. Engl. J. Med. 2015;372:11-20), 216 acute ischemic stroke patients underwent intra-arterial treatment following randomization. Among these patients, 79 were treated with general anesthesia and 137 with nongeneral anesthesia. The anesthesia choice was made on a case-by-case basis by each participating interventionalist.

The study’s primary endpoint – 90-day status rated as a good function based on a modified Rankin sale score of 0-2 – occurred in 38% of the intra-arterial patients treated with nongeneral anesthesia, 23% of the intra-arterial patients treated with general anesthesia, and 19% among the control patients who received standard treatment without intra-arterial intervention.

Dr. Olvert A. Berkhemer
Mitchel L. Zoler/Frontline Medical News
Dr. Olvert A. Berkhemer

“The effect on outcome that we found with intra-arterial treatment in MR CLEAN was not observed in the subgroup of patients treated with general anesthesia,” said Dr. Olvert A. Berkhemer at the International Stroke Conference. The analysis also showed that patients in the general and nongeneral anesthesia subgroups had similar stroke severity as measured by their National Institutes of Health Stroke Scale score, said Dr. Berkhemer, a researcher at the Academic Medical Center in Amsterdam.

But U.S. stroke specialists who heard the report cautioned that unidentified confounders might explain the results, and they also expressed skepticism that the Dutch observations would deter U.S. interventionalists from continuing to use general anesthesia when they perform endovascular procedures.

“The big concern [about this analysis] is that there may have been some things about the general anesthesia patients that they did not account for. I suspect there is a huge bias, that general anesthesia patients were sicker,” said Dr. Bruce Ovbiagele, professor and chief of neurology at the Medical University of South Carolina in Charleston. “At my institution they have used nongeneral anesthesia, but I have been at other places where they usually use general anesthesia; it is variable,” Dr. Ovbiagele added.

Dr. Bruce I. Ovbiagele
Mitchel L. Zoler/Frontline Medical News
Dr. Bruce I. Ovbiagele

Dr. Berkhemer’s analysis also showed that general anesthesia linked with a delayed start to treatment, but without resulting in a significant difference in time to reperfusion. He noted that “sometimes you cannot do the procedure without general anesthesia,” and in MR CLEAN 6 of the 137 intra-arterial patients who started with nongeneral anesthesia eventually received general anesthesia because of discomfort and pain, Dr. Berkhemer said at the conference, sponsored by the American Heart Association.

He speculated that patients who did not receive general anesthesia did better because they did not undergo acute episodes of reduced blood pressure caused by the hypotensive effect of general anesthesia.

Dr. Diederik W.J. .Dippel
Mitchel L. Zoler/Frontline Medical News
Dr. Diederik W.J. .Dippel

The findings reinforced the approach already used in most of the Dutch centers that participated in MR CLEAN, where nongeneral anesthesia is preferred when possible. “In our center we always use nongeneral anesthesia, we are happy with that and we are not going to change,” said Dr. Diederik W.J. Dippel, lead investigator of MR CLEAN and professor of neurology at Erasmus University Medical Center in Rotterdam, The Netherlands. This prejudice against general anesthesia would make it hard to run a trial in The Netherlands that matched the two anesthesia approaches against each other, Dr. Dippel added.

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

NASHVILLE, TENN. – When acute ischemic stroke patients undergo an emergency endovascular procedure is it best done with general anesthesia or nongeneral anesthesia?

A post hoc analysis of data collected by a Dutch randomized, controlled trial of intra-arterial therapy suggested that nongeneral anesthesia was associated with substantially better patient outcomes, and the findings convinced the Dutch investigators who ran the study to stick with nongeneral anesthesia as their default approach.

In MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) (N. Engl. J. Med. 2015;372:11-20), 216 acute ischemic stroke patients underwent intra-arterial treatment following randomization. Among these patients, 79 were treated with general anesthesia and 137 with nongeneral anesthesia. The anesthesia choice was made on a case-by-case basis by each participating interventionalist.

The study’s primary endpoint – 90-day status rated as a good function based on a modified Rankin sale score of 0-2 – occurred in 38% of the intra-arterial patients treated with nongeneral anesthesia, 23% of the intra-arterial patients treated with general anesthesia, and 19% among the control patients who received standard treatment without intra-arterial intervention.

Dr. Olvert A. Berkhemer
Mitchel L. Zoler/Frontline Medical News
Dr. Olvert A. Berkhemer

“The effect on outcome that we found with intra-arterial treatment in MR CLEAN was not observed in the subgroup of patients treated with general anesthesia,” said Dr. Olvert A. Berkhemer at the International Stroke Conference. The analysis also showed that patients in the general and nongeneral anesthesia subgroups had similar stroke severity as measured by their National Institutes of Health Stroke Scale score, said Dr. Berkhemer, a researcher at the Academic Medical Center in Amsterdam.

But U.S. stroke specialists who heard the report cautioned that unidentified confounders might explain the results, and they also expressed skepticism that the Dutch observations would deter U.S. interventionalists from continuing to use general anesthesia when they perform endovascular procedures.

“The big concern [about this analysis] is that there may have been some things about the general anesthesia patients that they did not account for. I suspect there is a huge bias, that general anesthesia patients were sicker,” said Dr. Bruce Ovbiagele, professor and chief of neurology at the Medical University of South Carolina in Charleston. “At my institution they have used nongeneral anesthesia, but I have been at other places where they usually use general anesthesia; it is variable,” Dr. Ovbiagele added.

Dr. Bruce I. Ovbiagele
Mitchel L. Zoler/Frontline Medical News
Dr. Bruce I. Ovbiagele

Dr. Berkhemer’s analysis also showed that general anesthesia linked with a delayed start to treatment, but without resulting in a significant difference in time to reperfusion. He noted that “sometimes you cannot do the procedure without general anesthesia,” and in MR CLEAN 6 of the 137 intra-arterial patients who started with nongeneral anesthesia eventually received general anesthesia because of discomfort and pain, Dr. Berkhemer said at the conference, sponsored by the American Heart Association.

He speculated that patients who did not receive general anesthesia did better because they did not undergo acute episodes of reduced blood pressure caused by the hypotensive effect of general anesthesia.

Dr. Diederik W.J. .Dippel
Mitchel L. Zoler/Frontline Medical News
Dr. Diederik W.J. .Dippel

The findings reinforced the approach already used in most of the Dutch centers that participated in MR CLEAN, where nongeneral anesthesia is preferred when possible. “In our center we always use nongeneral anesthesia, we are happy with that and we are not going to change,” said Dr. Diederik W.J. Dippel, lead investigator of MR CLEAN and professor of neurology at Erasmus University Medical Center in Rotterdam, The Netherlands. This prejudice against general anesthesia would make it hard to run a trial in The Netherlands that matched the two anesthesia approaches against each other, Dr. Dippel added.

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

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General anesthesia linked to worsened stroke outcomes
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Key clinical point: Post hoc analysis of acute ischemic stroke patients treated intra-arterially suggests that avoiding general anesthesia produces better long-term outcomes.

Major finding: After 90 days, 38% of patients treated without general anesthesia and 23% of those who received general anesthesia had good outcomes.

Data source: Analysis of 216 patients in the Dutch MR CLEAN trial who underwent treatment for acute ischemic stroke.

Disclosures: Dr. Berkhemer, Dr. Dippel, and Dr. Ovbiagele had no disclosures.