Distinguish neurogenic from nonneurogenic orthostatic hypotension

 

In order to distinguish neurogenic from nonneurogenic causes of orthostatic hypotension, looking at the change in heart rate (cHR) in relation to the change in systolic blood pressure (cSBP) may be superior to looking at heart rate alone.

A cHR/cSBP ratio of 0.492 beats per minute (bpm)/mm Hg had the best sensitivity and specificity to distinguish neurogenic from nonneurogenic causes, according to results of a prospective study published in Annals of Neurology.

Patients with a ratio less than 0.5 might need additional screening for primary or secondary causes of autonomic failure, according to researcher Lucy Norcliffe-Kaufmann, PhD, associate director of the Dysautonomia Center at NYU Langone Medical Center, New York.

“If you just look at the heart rate increase alone, of course it is blunted, but it doesn’t really give you the bigger picture that you get when you look at the heart rate in relation to the blood pressure fall,” Dr. Norcliffe-Kaufmann said in an interview.

Neurogenic orthostatic hypotension, which indicates an underlying pathology affecting autonomic neurons, has a much worse prognosis than does nonneurogenic orthostatic hypotension, according to Dr. Norcliffe-Kaufmann and her colleagues, who published the results on behalf of the Autonomic Disorders Consortium.

One key difference between the two groups, they added, is that patients with neurogenic orthostatic hypotension typically have little or no heart rate (HR) increase in the upright position, while patients with nonneurogenic orthostatic hypotension may have marked tachycardia.

Despite the importance of orthostatic HR changes in differential diagnosis, however, there has been no systematic evaluation of HR ranges that may be diagnostic, and proposed ranges have been based on expert clinical experience rather than clinical data, they said.

 

Accordingly, Dr. Norcliffe-Kaufmann and her colleagues conducted a study of consecutive adult patients referred for autonomic evaluation at sites of the U.S. Autonomic Consortium.

The analysis was based on 402 patients with orthostatic hypotension who had normal sinus rhythm at the time of evaluation. Of that group, 378 had neurogenic orthostatic hypotension and were diagnosed with Parkinson disease, dementia with Lewy bodies, pure autonomic failure, or multiple system atrophy.

Patients with neurogenic orthostatic hypotension had twice the fall in SBP versus those with nonneurogenic causes (–43 vs. –21 mm Hg; P less than .0001), yet only about a third of the HR increase (8 vs. 25 bpm; P less than .0001), researchers reported.

They found the cHR/cSBP ratio of 0.492 bpm/mm Hg had the best sensitivity (91.3%) and specificity (88.4%) to distinguish between patients with neurogenic and nonneurogenic orthostatic hypertension.

 

By contrast, orthostatic HR increase by itself was a poor discriminator, according to the researchers, who reported that an HR increase of less than 17 bpm had just moderate sensitivity (79%) and specificity (87%).

“Using this simple bedside test of how much the blood pressure falls and heart rate increases can help in screening these patients,” Dr. Norcliffe-Kaufmann said of the results. “Then they can be sent to an autonomic clinic to really confirm the diagnosis with a sophisticated autonomic function test.”

The researchers also sought to determine whether the differences in heart rate could distinguish between central and peripheral causes of neurogenic orthostatic hypotension. They found that heart rate increased more in patients with multiple system atrophy, but noted “considerable overlap” with patients with Lewy body disorders, according to the findings.

“It didn’t really pan out as a way to distinguish the two forms from one another with enough sensitivity or specificity,” Dr. Norcliffe-Kaufmann said.

 

The findings do suggest, however, that looking at the cHR/cSBP ratio could help identify neurogenic orthostatic hypotension earlier, reducing delays in treatment and decreasing the need for expensive testing, the researchers said.

“I think there will be a place for genuine, solid autonomic function tests, but many patients cannot get referred to these services, or they don’t have these specialist medical centers on their doorstep, particularly in rural communities,” Dr. Norcliffe-Kaufmann said in the interview.

The study was supported by the National institutes of Health Rare Disease Clinical Research Network. Dr. Norcliffe-Kaufmann and her coauthors reported no potential conflicts of interest.

SOURCE: Norcliffe-Kaufmann L et al. Ann Neurol. 2018 Mar;83(3):522-31.

 

In order to distinguish neurogenic from nonneurogenic causes of orthostatic hypotension, looking at the change in heart rate (cHR) in relation to the change in systolic blood pressure (cSBP) may be superior to looking at heart rate alone.

A cHR/cSBP ratio of 0.492 beats per minute (bpm)/mm Hg had the best sensitivity and specificity to distinguish neurogenic from nonneurogenic causes, according to results of a prospective study published in Annals of Neurology.

Patients with a ratio less than 0.5 might need additional screening for primary or secondary causes of autonomic failure, according to researcher Lucy Norcliffe-Kaufmann, PhD, associate director of the Dysautonomia Center at NYU Langone Medical Center, New York.

“If you just look at the heart rate increase alone, of course it is blunted, but it doesn’t really give you the bigger picture that you get when you look at the heart rate in relation to the blood pressure fall,” Dr. Norcliffe-Kaufmann said in an interview.

Neurogenic orthostatic hypotension, which indicates an underlying pathology affecting autonomic neurons, has a much worse prognosis than does nonneurogenic orthostatic hypotension, according to Dr. Norcliffe-Kaufmann and her colleagues, who published the results on behalf of the Autonomic Disorders Consortium.

One key difference between the two groups, they added, is that patients with neurogenic orthostatic hypotension typically have little or no heart rate (HR) increase in the upright position, while patients with nonneurogenic orthostatic hypotension may have marked tachycardia.

Despite the importance of orthostatic HR changes in differential diagnosis, however, there has been no systematic evaluation of HR ranges that may be diagnostic, and proposed ranges have been based on expert clinical experience rather than clinical data, they said.

 

Accordingly, Dr. Norcliffe-Kaufmann and her colleagues conducted a study of consecutive adult patients referred for autonomic evaluation at sites of the U.S. Autonomic Consortium.

The analysis was based on 402 patients with orthostatic hypotension who had normal sinus rhythm at the time of evaluation. Of that group, 378 had neurogenic orthostatic hypotension and were diagnosed with Parkinson disease, dementia with Lewy bodies, pure autonomic failure, or multiple system atrophy.

Patients with neurogenic orthostatic hypotension had twice the fall in SBP versus those with nonneurogenic causes (–43 vs. –21 mm Hg; P less than .0001), yet only about a third of the HR increase (8 vs. 25 bpm; P less than .0001), researchers reported.

They found the cHR/cSBP ratio of 0.492 bpm/mm Hg had the best sensitivity (91.3%) and specificity (88.4%) to distinguish between patients with neurogenic and nonneurogenic orthostatic hypertension.

 

By contrast, orthostatic HR increase by itself was a poor discriminator, according to the researchers, who reported that an HR increase of less than 17 bpm had just moderate sensitivity (79%) and specificity (87%).

“Using this simple bedside test of how much the blood pressure falls and heart rate increases can help in screening these patients,” Dr. Norcliffe-Kaufmann said of the results. “Then they can be sent to an autonomic clinic to really confirm the diagnosis with a sophisticated autonomic function test.”

The researchers also sought to determine whether the differences in heart rate could distinguish between central and peripheral causes of neurogenic orthostatic hypotension. They found that heart rate increased more in patients with multiple system atrophy, but noted “considerable overlap” with patients with Lewy body disorders, according to the findings.

“It didn’t really pan out as a way to distinguish the two forms from one another with enough sensitivity or specificity,” Dr. Norcliffe-Kaufmann said.

 

The findings do suggest, however, that looking at the cHR/cSBP ratio could help identify neurogenic orthostatic hypotension earlier, reducing delays in treatment and decreasing the need for expensive testing, the researchers said.

“I think there will be a place for genuine, solid autonomic function tests, but many patients cannot get referred to these services, or they don’t have these specialist medical centers on their doorstep, particularly in rural communities,” Dr. Norcliffe-Kaufmann said in the interview.

The study was supported by the National institutes of Health Rare Disease Clinical Research Network. Dr. Norcliffe-Kaufmann and her coauthors reported no potential conflicts of interest.

SOURCE: Norcliffe-Kaufmann L et al. Ann Neurol. 2018 Mar;83(3):522-31.

 

In order to distinguish neurogenic from nonneurogenic causes of orthostatic hypotension, looking at the change in heart rate (cHR) in relation to the change in systolic blood pressure (cSBP) may be superior to looking at heart rate alone.

A cHR/cSBP ratio of 0.492 beats per minute (bpm)/mm Hg had the best sensitivity and specificity to distinguish neurogenic from nonneurogenic causes, according to results of a prospective study published in Annals of Neurology.

Patients with a ratio less than 0.5 might need additional screening for primary or secondary causes of autonomic failure, according to researcher Lucy Norcliffe-Kaufmann, PhD, associate director of the Dysautonomia Center at NYU Langone Medical Center, New York.

“If you just look at the heart rate increase alone, of course it is blunted, but it doesn’t really give you the bigger picture that you get when you look at the heart rate in relation to the blood pressure fall,” Dr. Norcliffe-Kaufmann said in an interview.

Neurogenic orthostatic hypotension, which indicates an underlying pathology affecting autonomic neurons, has a much worse prognosis than does nonneurogenic orthostatic hypotension, according to Dr. Norcliffe-Kaufmann and her colleagues, who published the results on behalf of the Autonomic Disorders Consortium.

One key difference between the two groups, they added, is that patients with neurogenic orthostatic hypotension typically have little or no heart rate (HR) increase in the upright position, while patients with nonneurogenic orthostatic hypotension may have marked tachycardia.

Despite the importance of orthostatic HR changes in differential diagnosis, however, there has been no systematic evaluation of HR ranges that may be diagnostic, and proposed ranges have been based on expert clinical experience rather than clinical data, they said.

 

Accordingly, Dr. Norcliffe-Kaufmann and her colleagues conducted a study of consecutive adult patients referred for autonomic evaluation at sites of the U.S. Autonomic Consortium.

The analysis was based on 402 patients with orthostatic hypotension who had normal sinus rhythm at the time of evaluation. Of that group, 378 had neurogenic orthostatic hypotension and were diagnosed with Parkinson disease, dementia with Lewy bodies, pure autonomic failure, or multiple system atrophy.

Patients with neurogenic orthostatic hypotension had twice the fall in SBP versus those with nonneurogenic causes (–43 vs. –21 mm Hg; P less than .0001), yet only about a third of the HR increase (8 vs. 25 bpm; P less than .0001), researchers reported.

They found the cHR/cSBP ratio of 0.492 bpm/mm Hg had the best sensitivity (91.3%) and specificity (88.4%) to distinguish between patients with neurogenic and nonneurogenic orthostatic hypertension.

 

By contrast, orthostatic HR increase by itself was a poor discriminator, according to the researchers, who reported that an HR increase of less than 17 bpm had just moderate sensitivity (79%) and specificity (87%).

“Using this simple bedside test of how much the blood pressure falls and heart rate increases can help in screening these patients,” Dr. Norcliffe-Kaufmann said of the results. “Then they can be sent to an autonomic clinic to really confirm the diagnosis with a sophisticated autonomic function test.”

The researchers also sought to determine whether the differences in heart rate could distinguish between central and peripheral causes of neurogenic orthostatic hypotension. They found that heart rate increased more in patients with multiple system atrophy, but noted “considerable overlap” with patients with Lewy body disorders, according to the findings.

“It didn’t really pan out as a way to distinguish the two forms from one another with enough sensitivity or specificity,” Dr. Norcliffe-Kaufmann said.

 

The findings do suggest, however, that looking at the cHR/cSBP ratio could help identify neurogenic orthostatic hypotension earlier, reducing delays in treatment and decreasing the need for expensive testing, the researchers said.

“I think there will be a place for genuine, solid autonomic function tests, but many patients cannot get referred to these services, or they don’t have these specialist medical centers on their doorstep, particularly in rural communities,” Dr. Norcliffe-Kaufmann said in the interview.

The study was supported by the National institutes of Health Rare Disease Clinical Research Network. Dr. Norcliffe-Kaufmann and her coauthors reported no potential conflicts of interest.

SOURCE: Norcliffe-Kaufmann L et al. Ann Neurol. 2018 Mar;83(3):522-31.