The Impact of a Helicopter Emergency Medical System on Prognosis in Stroke Patients

Study Overview
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Brief Summary
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Stroke is a leading cause of death and disability, and 15 million people suffer a stroke each year; one-third die and one-third are left permanently disabled. Because the risk of stroke increases with age, it has been considered a disease of the elderly, but stroke also occurs in middle-aged people. Thrombolysis with tissue plasminogen activator (tPA) is the preferred choice of reperfusion therapy of ischemic stroke if performed within 4.5 hours from symptom onset. Time to thrombolysis is associated with improved outcome: the sooner the treatment, the less risk of serious - and possibly permanent - damage to the brain. Unfortunately, only a small fraction of stroke patients make it to thrombolysis within the 4.5-hour; one explanation may be system delays including prolonged transportation. In May 2010, the first physician-staffed Helicopter Emergency Medical Service (HEMS) was implemented in the Eastern part of Denmark. An observational study evaluating the short-term effects of HEMS implementation compared patients transported by conventional ground ambulance (Ground Emergency Medical Service (GEMS)) to patients transported by HEMS. Patients transported by helicopter had increased time to specialized care. However, both 30-day and 1-year mortality was slightly lower in patients transported by HEMS, although not significant, as was the degree of disability at three months measured by the modified Rankin Scale (mRS).

Official Title
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The Impact of a Helicopter Emergency Medical System on Prognosis in Stroke Patients

Conditions
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Thrombolysis

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients arriving at the regional stroke unit at Copenhagen University Hospital, Roskilde, suspected of an acute vascular condition within the geographical area covered by both HEMS and GEMS in a 40-month period from January 1st 2010 until April 30th 2013. Exclusion Criteria: For patients with multiple contacts; only the first contact is included in the data for analysis.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| HEMS patients<br>Patients suspected of suffering from a vascular condition within the geographical area covered by both HEMS and GEMS, and were transported by Helicopter Emergency Medical System (HEMS) to the regional stroke unit at Copenhagen University Hospital Roskilde in a 36-month period from May 1st 2010 until April 30th 2013. | |
| GEMS patients<br>Patients suspected of suffering from a vascular condition within the geographical area covered by both HEMS and GEMS, and were transported by Ground Emergency Medical System (GEMS) to the regional stroke unit at Copenhagen University Hospital Roskilde in a 40-month period from January 1st 2010 until April 30th 2013. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Risk of death during follow-up | Mortality during the follow-up period will be analysed for differences between GEMS and HEMS. Follow-up period is until May 1st 2015. Because of varying access to information on covariates depending on the diagnosis and treatment of the patient, we conduct the analysis as follows: 1) the whole study population; adjusted for sex and age, 2) patients who were suspected of suffering from a vascular condition; adjusted for sex, age and comorbidity (defined as one of the following conditions; diabetes, atrial fibrillation, hypertension, previous myocardial infarction, and previous stroke), and 3) patients who underwent thrombolysis; adjustment for sex, age, comorbidity, and initial National Institutes of Health Stroke Scale (NIHSS) score. | 2 - 5.5 years after admission to the stroke unit. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The risk of death at 30 day. | Patients are divided into the same three sub-groups and adjusted for the same potential confounders as described in the primary outcome analysis. | 30 days after admission to the stroke unit. | 
| Modified Rankin Scale (mRS) after three months. | Assessed in patients who underwent thrombolysis. | Three months | 
| The risk of involuntary early retirement during the follow-up period. | Assessed in all patients suspected of suffering from a vascular condition between 18 and 60 years of age to ensure a sample that was at risk of involuntary early retirement during the full follow-up period. | 2 - 5.5 years after admission to the stroke unit. | 
| The risk of reduced workability two years after the vascular event | Assessed in all patients suspected of suffering from a vascular condition between 18 and 60 years of age to ensure a sample that was at risk of involuntary early retirement during the full follow-up period. | Two years after admission to the stroke unit | 
| The percentage of time on social transfer payments during the first two years. | Assessed in all patients suspected of suffering from a vascular condition between 18 and 60 years of age to ensure a sample that was at risk of involuntary early retirement during the full follow-up period. | Two years after admission to the stroke unit | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Helicopter Emergency Medical System, Mortality, Labour market affiliation, Modified Rankin Scale