Stroke Doc

Stroke Patients Treated Faster If Arrive By Ambulance

A retrospective database study finds that stroke patients who were brought to the hospital by ambulance were treated more urgently than those who arrived by other means.

Summary:

(As reported by online Stroke Journal Report of the American Heart Association, 2/16/06)

Dr. Yousef Mohammad et al. conducted a study which analyzed  a large emergency services database, indentifying 630,000 patients who were treated for stroke in the emergency room.  The mode of arrival of stroke patients was categorized into one of three: (1) by ambulance, (2) walk-ins (arrival by their own means, whether walking, driving, etc.) or (3) by a public service other than ambulance (police, etc.) or unknown.   About half of the patients in the database arrived by ambulance, 43 percent were walk-ins, and 4 percent arrived by public service or by unknown means.  It was found that patients who arrived by ambulance were seen on average within 30 minutes, compared to 34 minutes for walk-ins and 55 minutes for those who arrived by public transportation or by unknown means.  Analysis of testing found that 73 percent of patients who came by ambulance underwent appropriate diagnostic imaging (MRI or CT scan), while only 63 percent of walk-ins received this imaging.  Only 60% of those arriving by public or unknown means received this imaging.

Commentary:

It is generally recommended that anyone who feels he/she is suffering from a stroke call 911, or have someone else make the call, to activate emergency services.  This is the safest approach since the ambulance personnel are skilled in administering potentially helpful therapies such as oxygen and IV fluids, and they may need to treat concomitant medical disorders.  The emergency room is also typically notified of the impending arrival of a stroke patient, which helps speed the evaluatory process once a patient arrives.

This study looked at the mode of arrival of patients, concluding that arrival by ambulance led to a (slight) reduction in time seen by physician, compared to arrival by your own transportation.  There was also a significant increase in the use of diagnostic imaging in those arriving by ambulance.  The results may be confounded, though, both by the severity of stroke and by whether stroke was the true diagnosis.  First of all, the severity of one's symptoms often affects decision making.  A patient who is experiencing mild facial numbness over the coarse of a few days may decide to be taken by family members to the emergency room, while someone with sudden weakness on one side and inability to speak will likely have an ambulance called for them.  The first case is indeed less urgent than the second, and therefore may account for the difference in evaluation speed by physicians in the emergency room.

The second point is that in many cases, the final diagnosis may not be a stroke.  Miscoding within the database, based on initial symptoms, but never corrected based on later information, may account for this.  My evidence for this is the overall high number of patients who did not receive diagnostic imaging.  I would venture to say that nearly 100 percent of patients suspected of having a stroke by ER physicians would undergo a CT scan or brain MRI.  The fact that 27-40 percent of patients did not undergo such imaging indicates that stroke was not seriously being considered as a diagnosis.  This is further demonstrated by the high percentage of patients who were sent home in the study (only 53 percent of walk-in patients were admitted to the hospital.) 

Thus, while it is best to call 911 in cases of suspected stroke and to be transported by ambulance, the data in this study used to support this conclusion are somewhat suspect.

TPA Use and Hemorrhage: No Increased Risk in Those Over Age 80

Tissue plasminogen activator (TPA) is a medication which is used to break up blood clots during an acute stroke.  A recent study finds that use of TPA in patients who were over 80 years of age did not lead to an excess of brain hemorrhages.

Summary:

(As reported in the December 2005 issue of Clinical Neurology News)

TPA (Tissue Plasminogen Activator) is used within hours of an acute ischemic stroke to break up the causative blood clot.  Unfortunately TPA can have the adverse effect of causing excessive bleeding, both systemically (at various sites in the body including the gastrointestinal tract) and in the brain itself.  There has been some hesitancy, on the part of physicians, to treat the elderly using TPA for fear that they are much more susceptible to this complication.  Dr. Demaerschalk et al. decided to see if this concern was justified.  Among 69 patients who received IV TPA at the Mayo Clinic in Scottsdale, Arizona, 21 were 80 years of age or older.  Analysis of the data for older patients revealed that they tended to have more severe strokes at initial presentation, having a stroke scale (NIHSS) on average of 16, compared with the moderately better result of 14 for the younger group.  After receiving TPA, about 50% of patients in the older group had a 4-point or greater improvement in their stroke scale.  The same degree of improvement was seen in the younger group.

In terms of life-threatening hemorrhages or brain hemorrhages that affect neurological outcome, there was in fact no significant difference between the two groups.  Despite this, long-term neurological outcomes were overall worse in the older group.  For example, three months after stroke, fewer than 20% of the older patients were living at home; compared with 70% of the younger group.

Commentary:

This study supports the concept that age alone should not exclude a person from receiving TPA for acute ischemic stroke.  The study should help neurologists feel more comfortable regarding the risk of intracranial hemorrhage with TPA use in this population, and may subsequently result in better stroke outcomes for this group of patients, if they are otherwise eligible to receive TPA.  The study also, though, indicates that stroke is overall not tolerated well by the elderly.  Either due to baseline neurological problems prior to the stroke, or complications arising from the stroke itself, the elderly have a higher chance of have a poor outcome three months after stroke than their younger counterparts.

Reduced Stroke Risk Associated with Fruit/Vegetable Intake

A large meta-analysis finds that increased consumption of fruits and vegetables is associated with reduced stroke risk.

Summary:

(Based on The Lancet, 2006; 367:320-26.)

Dr. Feng et al. performed a meta-analysis of eight other studies (previously completed in Japan, Europe, and the United States) looking at the association between fruit/vegetable consumption and stroke occurence.  The meta-analysis relied on more than 250,000 subjects' own recollection of their typical fruit and vegetable intake.  They were followed for an average of 13 years during which a total of 4,917 stroke events were reported.  The analysis found that those who ate 3-5 servings of fruits or vegetables per day had an 11% reduced risk of stroke compared to those who ate fewer than 3 servings per day.  In those who had even higher intakes of fruits and vegetables, more than 5 servings per day, the stroke risk was lowered by 26%.  In a subgroup analysis, it was found that both ischemic and hemorrhagic strokes were reduced in those eating more than 5 servings per day.

Commentary:

We must always look critically on analyses of this sort.  First of all, the study is a meta-analysis - which is an attempt to obtain more statistical power by pooling data gathered by potentially very different means.  It is not clear to what degree data can be mashed together in this manner; and it is certainly less trustworthy than a similarly large, well-designed prospective study.  Second, in an observational study, there is concern regarding the third-variable effect.  People who pay attention to their health (by exercising, controlling their blood pressures, keeping their weights down) are probably already aware of the potentially beneficial effects of eating fruits and vegetables and therefore will be eating more of them.  Thus, people who maintain a healthy lifestyle overall (the third variable) will tend to have fewer strokes, but perhaps only due to their other healthy activities, not to the fruit and vegetable intake.  Although researchers can statistically reduce this effect, it is difficult to eliminate it entirely.

Taken at face value, though, these results certainly support the intake of 5 or more servings of fruit and vegetables per day, to reduce stroke risk.  A serving can be considered one medium sided apple, banana, or the like; or 1/2 a cup of vegetables or fruit.  There are many proposed mechanisms by which higher vegetable and fruit intake may reduce stroke risk.  These include the protective effect of anti-oxidants, reduced intake of other foods including fat (from meats) and simple carbohydrates, cholesterol binding from fiber intake, lower blood pressures due to potassium intake, or special nutrients contained in vegetables and fruits.