Research fundamentals: IV. Choosing a research design.

Once a research question or hypothesis has been derived, the investigator must determine which research methodology can best answer his or her question. Prospective, randomized, controlled trials are often considered the sine qua non of research design. However, this study design is not always feasible, and often an alternate design will adequately answer the question at significantly less cost. All research designs have potential advantages and limitations. The decision of which study design to use is often a compromise between science and resources. This article was prepared by members of the SAEM Research Committee to describe the fundamental research concepts of research design. This paper defines different research methodologies and discusses their different uses, strengths, and weaknesses. It also describes the process of randomization and blinding. Finally, the concept of bias and its remedies is delineated.

Emergency department management of patients with seizures: a multicenter study.

OBJECTIVES: Patients with seizure disorders are common in the emergency department (ED), yet little is known regarding the management of these patients. This study was performed to define the frequency of patients with seizure disorders in the ED patient population and to determine possible seizure etiologies, characteristics of diagnostic activities, treatments, and dispositions. METHODS: Twelve EDs monitored all patients with a chief complaint related to seizure disorders presenting over 18.25 days (5% of the calendar year) in late 1997. Retrospective chart review was used to gather specific data regarding these consecutive cases. RESULTS: Of the 31,508 patients who presented to these 12 EDs during the study period, 368 (1.2%) had complaints related to seizures. Three hundred sixty-two charts were available for analysis and make up the study population. Two hundred fifty-seven (71%) utilized emergency medical services (EMS) for transport and care. Advanced care, including intravenous access, laboratory work, cardiac monitoring, or oxygen administration, was utilized in 304 (84%) patients. Antiepileptic drugs were given in 199 (55%) patients. Ethanol withdrawal or low antiepileptic drug levels were implicated as contributing factors in 177 (49%) of patients. New-onset seizures were thought to be present in 94 (26%) patients. Status epilepticus occurred in only 21 (6%) patients. Ninety-eight (27%) of all patients were admitted to the hospital. CONCLUSIONS: Patients with presenting complaints related to seizures are frequent in the ED population and make considerable demands on EMS and ED resources. Six percent of patients with seizure-related presentations were in status epilepticus and more than a fourth of all patients required hospitalization.

The scapular manipulation technique for the reduction of acute anterior shoulder dislocations.

Anterior shoulder dislocations are a common occurrence in busy emergency departments. Numerous techniques for treating this problem have been reported. The majority of these techniques use traction and leverage of the humerus, often requiring considerable force and causing significant patient discomfort. We report a simple, relatively painless, and atraumatic method of shoulder reduction involving manipulation of the scapula as well as the humerus. This technique has been used in our emergency department with considerable success and no complications.

Embolization of calcific thrombi after tissue plasminogen activator treatment.

BACKGROUND AND PURPOSE: Embolic stroke has been reported after thrombolysis in cardiac patients but has not yet been documented after thrombolytic therapy for acute ischemic stroke. DESCRIPTION OF CASES: Patient 1 had a calcific embolus in the right M1 region on head computed tomography (CT) scan when treated with tissue plasminogen activator (tPA). Repeat imaging within hours showed distal migration of calcific fragments into the M2 region. Patient 2 had a calcific embolus in the right M1 region, as well as distal calcific emboli in multiple vascular distributions on initial head CT scan. She was treated with intravenous tPA but became unresponsive within 2 hours. Repeat imaging showed new calcium-density signal in the basilar artery. CONCLUSIONS: We present 2 cases of radiographically evident, calcific embolization after tPA therapy for acute ischemic stroke. Emboli with a calcific component may lyse with tPA, but such patients should be carefully monitored for distal or recurrent embolization.

IV tissue plasminogen activator use in acute stroke: experience from a statewide registry.

OBJECTIVE: To assess the use of IV recombinant tissue plasminogen activator (rt-PA) in a statewide hospital-based stroke registry and to identify factors associated with its use among eligible patients. METHODS: A modified stratified sampling scheme was used to obtain a representative sample of 16 hospitals. Prospective case ascertainment and data collection were used to identify all acute stroke admissions over a 6-month period. Subjects eligible for IV rt-PA were defined as those who arrived within 3 hours of onset, who had no evidence of hemorrhage on initial brain image, and who had no physician-documented reasons for non-treatment with IV rt-PA. Multivariate logistic regression was used to identify factors associated with IV rt-PA use. RESULTS: Of 2,566 stroke admissions, 330 (12.9%) met the eligibility criteria for rt-PA treatment, and of these 43 (13%) received IV rt-PA treatment. Among 2,236 admissions excluded from consideration, 21% had evidence of hemorrhage on initial imaging, 35% had unknown stroke onset times, 38% had an onset to arrival time >3 hours, and 6% had physician documented contraindications. Among eligible patients, being male, use of emergency medical services, and rapid presentation were associated with increased IV rt-PA use. CONCLUSIONS: Treatment with IV rt-PA was underutilized in this hospital-based stroke registry. The primary reason for nontreatment was delayed presentation. Reducing prehospital and in-hospital response times would help increase IV rt-PA use, as would greater emergency medical services use. Improving the documentation of onset times would help clarify the underlying causes of delayed presentation.

Prospective evaluation of the scapular manipulation technique in reducing anterior shoulder dislocations.

STUDY OBJECTIVE: To evaluate the speed, efficacy, and safety of the scapular manipulation technique in reducing acute anterior shoulder dislocations. DESIGN: Prospective study. SETTING: Urban emergency department with an annual census of 65,000 patients. PARTICIPANTS: Forty-eight adult patients with acute anterior shoulder dislocation. INTERVENTIONS: Patients had an initial neurovascular and radiographic evaluation performed. They were sedated with IV fentanyl and midazolam. The shoulder was reduced using the scapular manipulation technique. The patient was re-evaluated for any evidence of complication. The total dose of analgesic required and time to reduction were recorded. RESULTS: The scapular manipulation technique was successful in 46 of 48 (96%) cases. The average time to reduction was 6.05 minutes, and no complications were detected. Average doses of 1.83 mg midazolam and 204 micrograms fentanyl were required for reduction. CONCLUSION: The scapular manipulation technique is a very fast, effective, safe method of reducing anterior shoulder dislocations in the ED. [Kothari RU, Dronen SC: Prospective evaluation of the scapular manipulation technique in reducing anterior shoulder dislocations.

A nationwide prehospital stroke survey.

OBJECTIVES: To identify deficiencies in stroke knowledge among prehospital providers. METHODS: A nationwide multiple-choice survey was sent to 689 paramedics (EMT-Ps) and 294 advanced EMTs (EMT-Is) from a random selection of the National Registry of Emergency Medical Technicians database. Of the 23 questions, five addressed demographic information, four quantity of training, five general knowledge, 6 and seven management, and two open-ended questions addressed the signs, symptoms, and risk factors of stroke. The EMT-P and EMT-I answers were compared using chi-square analysis or Fisher's exact test. RESULTS: Of the 355 (36%) respondents, 256 (72%) were EMT-Ps and 99 (28%) were EMT-Is. Virtually all the EMT-Ps (99%) and EMT-Is (98%) knew that a stroke injures the brain, but only 199 (78%) of the EMT-Ps and 47 (47%) of the EMT-Is correctly defined a transient ischemic attack (TIA) (p < 0.001). Slurred speech, weakness/ paralysis, and altered mental status were the three most commonly cited symptoms of stroke by both groups. The EMT-Ps were more likely to recognize that dextrose is potentially harmful to stroke patients [EMT-P = 216 (85%), EMT-I = 71 (72%), p = 0.005]; 169 (66%) of the EMT-Ps and 75 (76%) of the EMT-Is felt that elevated blood pressures should be lowered in the prehospital setting. Only 93 (36%) of the EMT-Ps and 22 (22%) of the EMT-Is knew that tissue plasminogen activator (tPA) must be given within three hours of symptom onset (p = 0.01). CONCLUSION: Most EMS providers are knowledgeable about the symptoms of stroke but are unaware of the therapeutic window for thrombolysis and the recommended avoidance of prehospital blood pressure reduction. In addition, further education is needed regarding TIAs.

Cincinnati Prehospital Stroke Scale: reproducibility and validity.

STUDY OBJECTIVE: The Cincinnati Prehospital Stroke Scale (CPSS) is a 3-item scale based on a simplification of the National Institutes of Health (NIH) Stroke Scale. When performed by a physician, it has a high sensitivity and specificity in identifying patients with stroke who are candidates for thrombolysis. The objective of this study was to validate and verify the reproducibility of the CPSS when used by prehospital providers. METHODS: The CPSS was performed and scored by a physician certified in the use of the NIH Stroke Scale (gold standard). Simultaneously, a group of 4 paramedics and EMTs scored the same patient. RESULTS: A total of 860 scales were completed on a convenience sample of 171 patients from the emergency department and neurology inpatient service. Of these patients, 49 had a diagnosis of stroke or transient ischemic attack. High reproducibility was observed among prehospital providers for total score (intraclass correlation coefficient [rI],.89; 95% confidence interval [CI],.87 to.92) and for each scale item: arm weakness, speech, and facial droop (.91,.84, and.75, respectively). There was excellent intraclass correlation between the physician and the prehospital providers for total score (rI,.92; 95% CI,.89 to.93) and for the specific items of the scale (.91,.87, and.78, respectively). Observation by the physician of an abnormality in any 1 of the 3 stroke scale items had a sensitivity of 66% and specificity of 87% in identifying a stroke patient. The sensitivity was 88% for identification of patients with anterior circulation strokes. CONCLUSION: The CPSS has excellent reproducibility among prehospital personnel and physicians. It has good validity in identifying patients with stroke who are candidates for thrombolytic therapy, especially those with anterior circulation stroke.

Emergency physicians. Accuracy in the diagnosis of stroke.

BACKGROUND AND PURPOSE: The role of emergency physicians in trials of acute stroke therapy is expanding. We investigated the ability of emergency physicians to accurately identify patients with stroke. METHODS: We reviewed all 446 patients who were evaluated in the emergency department and had an inpatient admitting or discharge diagnosis of ischemic or hemorrhagic stroke from May 1, 1992, to June 30, 1993. The final admitting diagnosis made by the emergency physician was compared with the final hospital discharge diagnosis, 95% of which were made by neurologists or neurosurgeons. RESULTS: All 76 patients with a final discharge diagnosis of intracerebral or subarachnoid hemorrhage were correctly diagnosed by the emergency physicians (sensitivity, 100%; positive predictive value, 100%). Of the 351 patients with a final discharge diagnosis of ischemic stroke or transient ischemic attack, 346 were correctly identified by the emergency physicians (sensitivity, 98.6%; positive predictive value, 94.8%). Nineteen patients were diagnosed with stroke or transient ischemic attack by the emergency physician but had a final discharge diagnosis other than stroke. Discharge diagnoses included paresthesia or numbness of unknown causes (3), seizure (2), complicated migraine (2), peripheral neuropathy (2), cranial nerve neuropathy (2), psychogenic paralysis (1), and other (7). CONCLUSIONS: Emergency physicians at a large urban teaching hospital with a comprehensive stroke intervention program can accurately identify patients with stroke, particularly hemorrhagic stroke. If similar accuracy can be documented in other types of hospitals, emergency physicians may become key providers of urgent stroke intervention.

The ABCs of measuring intracerebral hemorrhage volumes.

BACKGROUND AND PURPOSE: Hemorrhage volume is a powerful predictor of 30-day mortality after spontaneous intracerebral hemorrhage (ICH). We compared a bedside method of measuring CT ICH volume with measurements made by computer-assisted planimetric image analysis. METHODS: The formula ABC/2 was used, where A is the greatest hemorrhage diameter by CT, B is the diameter 90 degrees to A, and C is the approximate number of CT slices with hemorrhage multiplied by the slice thickness. RESULTS: The ICH volumes for 118 patients were evaluated in a mean of 38 seconds and correlated with planimetric measurements (R2 = 9.6). Interrater and intrarater reliability were excellent, with an intraclass correlation of .99 for both. CONCLUSIONS: We conclude that ICH volume can be accurately estimated in less than 1 minute with the simple formula ABC/2.

Does the National Institutes of Health Stroke Scale favor left hemisphere strokes? NINDS t-PA Stroke Study Group.

BACKGROUND AND PURPOSE: The National Institutes of Health Stroke Scale (NIHSS) is a valid, reproducible scale that measures neurological deficit. Of 42 possible points, 7 points are directly related to measurement of language compared with only 2 points related to neglect. METHODS: We examined the placebo arm of the NINDS t-PA stroke trial to test the hypothesis that the total volume of cerebral infarction in patients with right hemisphere strokes would be greater than the volume of cerebral infarction in patients with left hemisphere strokes who have similar NIHSS scores. The volume of stroke was determined by computerized image analysis of CT films and CT images stored on computer tape and optical disks. Cube-root transformation of lesion volume was performed for each CT. Transformed lesion volume was analyzed in a logistic regression model to predict volume of stroke by NIHSS score for each hemisphere. Spearman rank correlation was used to determine the relation between the NIHSS score and lesion volume. RESULTS: The volume for right hemisphere stroke was statistically greater than the volume for left hemisphere strokes, adjusting for the baseline NIHSS (P<0. 001). For each 5-point category of the NIHSS score <20, the median volume of right hemisphere strokes was approximately double the median volume of left hemisphere strokes. For example, for patients with a left hemisphere stroke and a 24-hour NIHSS score of 16 to 20, the median volume of cerebral infarction was 48 mL (interquartile range 14 to 111 mL) as compared with 133 mL (interquartile range 81 to 208 mL) for patients with a right hemisphere stroke (P<0.001). The median volume of a right hemisphere stroke was roughly equal to the median volume of a left hemisphere stroke in the next highest 5-point category of the NIHSS. The Spearman rank correlation between the 24-hour NIHSS score and 3-month lesion volume was 0.72 for patients with left hemisphere stroke and 0.71 for patients with right hemisphere stroke. CONCLUSIONS: For a given NIHSS score, the median volume of right hemisphere strokes is consistently larger than the median volume of left hemisphere strokes. The clinical implications of our finding need further exploration.