Biomedical subjects

J C Torner

Publications and source records attributed to J C Torner.

At least 37 records · Page 2Linked to original sources

PubMed1997

Determinants of bone mineral density in postmenopausal white Iowans.

BACKGROUND: Osteoporosis is a major health problem for older individuals. For women, development of osteoporosis is a function of the accretion of "peak" bone mass in the third decade, age at menopause, and rate of bone loss with aging. Low bone mineral density (BMD) is a major risk factor for osteoporosis and fracture. The purpose of this study was to identify life style, nutritional, medical, and genetic predictors of low BMD in postmenopausal Iowa women. METHODS: One hundred thirty-four postmenopausal White women ranging in age from 57 to 81 years were included in this case-control study. Bone mineral density was measured at the femoral neck, using dual photon X-ray absorptiometry (Hologic 2000 QDR). Sixty-six women with BMD measurements below 0.68 g/cm2 (the bottom quartile of the BMD distribution in the population from which participants were recruited), and 68 women with values at or above 0.83 g/cm2 (the top quartile of the BMD distribution in the same population) were included. Information about environmental, nutritional, medical, and life style modifiers of BMD was obtained by written questionnaire and telephone interview. To assess familial factors that might influence BMD, we obtained a detailed family history for each participant. In addition, we tested the hypothesis that allelic variation at the Vitamin D receptor (VDR), and the type I collagen gene (COL1A1 and COL1A2) loci influence BMD. RESULTS: Weight, loss of height, age, and age at menopause were strong predictors of BMD in our population. After adjustment for these differences, we found no effect of genotype at the COL1A1, COL1A2, and VDR loci on BMD. CONCLUSIONS: Bone mineral density is a complex trait that is influenced by several different modifiers; in the present study, weight was the best predictor of postmenopausal BMD. While several studies suggest that VDR genotype is an important determinant of BMD, we did not find this association in our population, nor did we identify an association between allelic variation at the type I collagen gene loci and BMD. Identification of genes that determine body mass index may provide additional insight into risk factors for low BMD, and osteoporotic fractures.

Aged↗

PubMed1997

Recumbency in thoracolumbar fractures.

Fractures of the thoracic and lumbar spine are often treated successfully without surgery. Patients best suited for recumbency are those without deficit and minimal angular deformity and canal compromise. Angulation less than 20 dg, residual spinal canal of 50% or greater, and an anterior body height greater than 50% of the posterior height were additional criteria used in selecting recumbency. Patients were kept at bed rest for 1 to 4 weeks or until their pain resolved. They were then mobilized gradually in molded thoracolumbar orthoses for 3 to 5 months with sequential radiographs.

Adult↗

PubMed1997

Epidemiology of stroke in requiring intensive care.

Stroke is a leading cause of death and disability, particularly in the elderly population. The evolution of stroke prevention and treatment has reached a new stage whereby rapid evaluation and intervention can prevent stroke occurrence and its consequences. A stroke system much like a trauma system can be useful in getting patients to recognize signs and symptoms of stroke, mobilizing the emergency medical system (EMS), conducting diagnostic studies promptly, treating patients in a timely manner consistent with their disease process, stopping progression through monitoring and treatment, and beginning rehabilitation as early as feasible. The neurointensive care unit (neuro-ICU) is a key component of the system. It provides the monitoring and treatment for progressing stroke and its complications. Patients who might be suitable for neurointensive care are those with severe strokes, those receiving thrombolytic therapy, those receiving hypervolemia-hypertensive-hemodilution therapy, those at risk for intracranial and medical complications, and inhospital strokes following medical and surgical procedures. In order for patients to reach the neuro-ICU, education of patients, EMS providers, physicians, and hospital administrators with regard to the need for rapid response and intensive care is needed. The saga of myocardial infarction reaction is an example of the way a system of response can be developed. The concept of brain attack should alert the community and the healthcare providers of the urgency of stroke care and the need for a stroke system with neurointensive care as the therapeutic key.

Cerebrovascular Disorders↗

PubMed1996

Randomised trial of effect of alendronate on risk of fracture in women with existing vertebral fractures. Fracture Intervention Trial Research Group.

BACKGROUND: Previous studies have shown that alendronate can increase bone mineral density (BMD) and prevent radiographically defined (morphometric) vertebral fractures. The Fracture Intervention Trial aimed to investigate the effect of alendronate on the risk of morphometric as well as clinically evident fractures in postmenopausal women with low bone mass. METHODS: Women aged 55-81 with low femoral-neck BMD were enrolled in two study groups based on presence or absence of an existing vertebral fracture. Results for women with at least one vertebral fracture at baseline are reported here. 2027 women were randomly assigned placebo (1005) or alendronate (1022) and followed up for 36 months. The dose of alendronate (initially 5 mg daily) was increased (to 10 mg daily) at 24 months, with maintenance of the double blind. Lateral spine radiography was done at baseline and at 24 and 36 months. New vertebral fractures, the primary endpoint, were defined by morphometry as a decrease of 20% (and at least 4 mm) in at least one vertebral height between the baseline and latest follow-up radiograph. Non-spine clinical fractures were confirmed by radiographic reports. New symptomatic vertebral fractures were based on self-report and confirmed by radiography. FINDINGS: Follow-up radiographs were obtained for 1946 women (98% of surviving participants). 78 (8.0%) of women in the alendronate group had one or more new morphometric vertebral fractures compared with 145 (15.0%) in the placebo group (relative risk 0.53 [95% Cl 0.41-0.68]). For clinically apparent vertebral fractures, the corresponding numbers were 23 (2.3%) alendronate and 50 (5.0%) placebo (relative hazard 0.45 [0.27-0.72]). The risk of any clinical fracture, the main secondary endpoint, was lower in the alendronate than in the placebo group (139 [13.6%] vs 183 [18.2%]; relative hazard 0.72 [0.58-0.90]). The relative hazards for hip fracture and wrist fracture for alendronate versus placebo were 0.49 (0.23-0.99) and 0.52 (0.31-0.87). There was no significant difference between the groups in numbers of adverse experiences, including upper-gastrointestinal disorders. INTERPRETATION: We conclude that among women with low bone mass and existing vertebral fractures, alendronate is well tolerated and substantially reduces the frequency of morphometric and clinical vertebral fractures, as well as other clinical fractures.

Aged↗

PubMed1996

Method to electronically collect emergency department data.

STUDY OBJECTIVE: To describe the development and completeness of an electronic injury-surveillance system, the Rural Injury Surveillance System (RISS). METHODS: The emergency departments of nine rural Iowa hospitals submitted information on all patients treated from May 1993 through June 1994. RESULTS: The EDs submitted information on 23,594 patients with 32,445 different injury, disease, or follow-up visits. On the basis of comparison with the handwritten ED logbook, 90% of visits were also available in the RISS. Of the visits recorded in the RISS, 99% were also recorded in the logbook. The proportion of missing diagnostic codes decreased from a high of 22.6% in May 1993 to 8.1% in June 1994. The proportion of missing external cause codes was about 25% at the end of the study period. The proportion of missing industry and occupational codes was less than 5% at the end of the study period. CONCLUSION: Our findings show that complete, computerized, ED-based injury surveillance in rural EDs is possible and should be developed further.

Data Collection↗

PubMed1996

Response of spinal cord blood flow to the nitric oxide inhibitor nitroarginine.

OBJECTIVE: The extent to which nitric oxide (NO) is involved in the modulation of spinal cord blood flow (SCBF) in the uninjured and injured cord is unknown. To elucidate these questions, the following experiments in anesthetized rats were conducted. METHODS: Because NO is an unstable free radical with a half-life of seconds, its role can be understood through the study of the NO synthase inhibitor L-NG-nitroarginine (L-NOARG). L-NOARG was administered intravenously for 30 minutes at a dose of 100 or 500 micrograms/kg/min in 12 and 10 uninjured animals, respectively. SCBF fluctuations at C7-T1 were measured using laser doppler flowmetry. In a second set of 12 rats, L-NOARG (500 micrograms/kg/min) was administered 10 minutes before spinal cord injury using a modified aneurysm clip at C7-T1 and continued for 30 minutes thereafter. RESULTS: In the uninjured animals, L-NOARG was associated with a dose-dependent increase in mean arterial pressure of 20 to 80% above baseline (P = 0.0001), together with a dose-related decrease in SCBF (P = 0.0373). In the injured animals, L-NOARG was associated with a 48% increase in mean arterial pressure. With L-NOARG, the changes in SCBF from baseline after injury were similar to those of noninjured controls (n = 25) and significantly less than injury controls (n = 18) or those receiving phenylephrine (n = 8). CONCLUSION: NO synthase inhibitors, by reducing available NO, cause systemic vasoconstriction and a decrease in SCBF in the uninjured spinal cord. In the injured spinal cord, the administration of L-NOARG results in a redistribution of blood flow with an augmentation in posttraumatic SCBF at the injury site.

Animals↗

PubMed1996

Lifetime cost of stroke in the United States.

BACKGROUND AND PURPOSE: Stroke imposes a substantial economic burden on individuals and society. This study estimates the lifetime direct and indirect costs associated with the three major types of stroke: subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), and ischemic stroke (ISC). METHODS: We developed a model of the lifetime cost of incident strokes occurring in 1990. An epidemiological model of stroke incidence, survival, and recurrence was developed based on a review of the literature. Data on direct cost of treating stroke were obtained from Medicare claims data, the 1987 National Medical Expenditure Survey (NMES), and insurance claims data representing a group of large, self-insured employers. Indirect costs (the value of foregone market and nonmarket production) associated with premature morbidity and mortality were estimated based on data from the US Bureau of Economic Analysis and the 1987 NMES. RESULTS: The lifetime cost per person of first strokes occurring in 1990 is estimated to be $228,030 for SAH, $123,565 for ICH, $90,981 for ISC, and $103,576 averaged across all stroke sub-types. Indirect costs accounted for 58.0% of lifetime costs. Aggregate lifetime cost associated with an estimated 392,344 first strokes in 1990 was $40.6 billion: $5.6 billion for SAH, $6.0 billion for ICH, and $29.0 billion for ISC. Acute-care costs incurred in the 2 years following a first stroke accounted for 45.0%, long-term ambulatory care accounted for 35.0%, and nursing home costs accounted for 17.5% of aggregate lifetime costs of stroke. CONCLUSIONS: The lifetime cost of stroke varies considerably by type of stroke and entails considerable costs beyond the first 2 years after a stroke.

Adolescent↗

PubMed1996

Incidence and prevalence of intracranial vascular malformations in Olmsted County, Minnesota, 1965 to 1992.

We used the Mayo Clinic medical records linkage system to detect all cases of intracranial vascular malformation (IVM) among residents of Olmsted County, Minnesota from 1965 to 1992 and found 48 IVMs over the 27-year period, including four patients with IVM detected at autopsy, without prior symptoms. Twenty-nine of 48 patients were symptomatic at presentation. From 1985 to 1992, the age- and sex-adjusted detection rate for IVMs excluding asymptomatic autopsy cases was 2.75 in 100,000 person-years (P-Y) (95% CI, 1.6 to 3.9). From 1965 to 1992, the detection rate was 1.84 in 100,000 P-Y (95% CI, 1.3 to 2.4). On January 1, 1990, the age- and sex-adjusted prevalence rate of identified IVMs was 19.0 in 100,000 P-Y (95% CI, 10.5 to 27.5). Detection rates increased from 1965 to 1992, probably due to increased identification of cases because of advances in imaging technology. This study provides unique data on incidence rates of detection and prevalence of IVMs on a population basis.

Adolescent↗

PubMed1996

Epidemiologic evidence for a changing natural history of myasthenia gravis.

OBJECTIVE: To survey the epidemiologic literature for evidence of an increasing prevalence of myasthenia gravis (MG) over time, and to explore the reasons for the increase. DATA SOURCES: We found population-based reports of the epidemiology of MG by searching bibliographic databases. We used MG, epidemiology, prevalence, incidence, and mortality as search terms. STUDY SELECTION: We included population-based studies that reported the number of cases and the time period from which rates were calculated. STATISTICAL METHODS: We performed a regression analysis of rates versus date of study, comparing the slopes of regression lines for prevalence, incidence, and mortality. We performed a second analysis grouping rates by decade of study and calculating a mean rate weighted by the size of the population studied. We calculated 95% confidence intervals for each rate. RESULTS: We included 33 studies from 1950 through 1995. Prevalence and incidence rates increased over time, but the regression line for prevalence significantly exceeded that for incidence. Mortality rates declined slightly. The weighted means for prevalence rose significantly, but there was no significant change in incidence or mortality. CONCLUSION: The prevalence of MG has increased over the past forty-five years, probably because patients with the disease have longer life spans owing to present-day treatment.

Adult↗

PubMed1996

Gender-related differences in aneurysmal subarachnoid hemorrhage.

Female gender is a recognized risk factor for the occurrence of aneurysmal subarachnoid hemorrhage. In the present study the authors analyzed differences in admission characteristics and outcome between 578 women (64%) and 328 men (36%) who were enrolled in a recently completed clinical trial. The female-to-male ratio was nearly 2:1. The women in the study were older than the men (mean age 51.4 years vs 47.3 years, respectively, p<0.001). Female patients harbored aneurysms of the internal carotid artery more frequently than male patients (36.8% vs. 18.0%, p<0.001) and more often had multiple aneurysms (32.4% vs. 17.6%, p<0.001). On the other hand, anterior cerebral artery aneurysms were more commonly encountered in men (46.1% in men vs. 26.6% in women, p<0.001). Other baseline prognostic factors were balanced between the gender groups. Surgery was performed equally in both sexes (98%), although the time to operation was shorter for women (mean 3.6 days for women vs. 5.3 days for men, p = 0.0002). In the placebo group, the occurrence of vasospasm was not statistically different between the two groups. Primary causes of death and disability were the same, and favorable outcome rates at 3 months were not statistically different between the genders (69.7% for women vs. 73.4% for men, p = 0.243). The odds of a favorable outcome in women versus one in men were not statistically significant either before of after adjustment for age. These observations lead the authors to suggest that although women are older and harbor more aneurysms, the 3-month outcome for women and men who experience aneurysmal subarachnoid hemorrhage is the same.

Adult↗

PubMed1996

Frequency of intracranial hemorrhage as a presenting symptom and subtype analysis: a population-based study of intracranial vascular malformations in Olmsted Country, Minnesota.

The purpose of this study was to determine the symptoms at presentation and the incidence of intracranial hemorrhage (ICrH) caused by intracranial vascular malformations (IVMs) in a defined population. The authors used the Mayo Clinic medical records linkage system to detect all cases of IVM among residents of Olmsted County, Minnesota, during the period 1965 through 1992. Forty-eight IVMs were detected over the 27-year period. Twenty-nine of the 48 patients were symptomatic at presentation. The most common presenting symptom was ICrH, which was present in 20 patients, 69% of all symptomatic cases. Sixty-five percent of arteriovenous malformations (AVMs) presented with ICrH. The most common subtype of ICrH was intracerebral hemorrhage, which was found in nine of 20 patients; the second most common subtype was subarachnoid hemorrhage. The peak occurrence of hemorrhage was during the fifth decade of life. The age- and gender-adjusted occurrence of a first ICrH from an IVM among residents of Olmsted County, Minnesota was 0.82 per 100,000 person years (95% confidence interval 0.46-1.19). There was no increase in the detection of IVM-related ICrH throughout the study period. The 30-day mortality rate following ICrH was 17.6% for patients with an AVM and 25% for all patients with IVMs. This study provides unique data on symptoms at presentation and the incidence of ICrH and hemorrhage subtypes from IVMs on a population basis.

Adolescent↗

PubMed1996

Age and outcome after aneurysmal subarachnoid hemorrhage: why do older patients fare worse?

Advanced age is a recognized prognostic indicator of poor outcome after subarachnoid hemorrhage (SAH). The relationship of age to other prognostic factors and outcome was evaluated using data from the multicenter randomized trial of nicardipine in SAH conducted in 21 neurosurgical centers in North America. Among the 906 patients who were studied, five different age groups were considered: 40 years or less, 41 to 50, 51 to 60, 61 to 70, and more than 71 years. Twenty-three percent of the individuals enrolled were older than 60 years of age. Women outnumbered men in all age groups. Level of consciousness (p = 0.0002) and World Federation of Neurological Surgeons grade (p = 0.0001) at admission worsened with advancing age. Age was also related to the presence of a thick subarachnoid clot (p = 0.0001), intraventricular hemorrhage (p = 0.0003), and hydrocephalus (p = 0.0001) on an admission computerized tomography scan. The rebleeding rate increased from 4.5% in the youngest age group to 16.4% in patients more than 70 years of age (p = 0.002). As expected, preexisting medical conditions, such as diabetes (p = 0.028), hypertension (p = 0.0001), and pulmonary (p = 0.0084), myocardial (p = 0.0001), and cerebrovascular diseases (p = 0.0001), were positively associated with age. There were no age-related differences in the day of admission following SAH, timing of the surgery and/or location, and size (small vs. large) of the ruptured aneurysm. During the treatment period, the incidence of severe complications (that is, those complications considered life threatening by the reporting investigator) increased with advancing age, occurring in 28%, 33%, 36%, 40%, and 46% of the patients in each advancing age group, respectively (p = 0.0002). No differences were observed in the reported frequency of surgical complications. No age-related differences were found in the overall incidence of angiographic vasospasm; however, symptomatic vasospasm was more frequently reported in the older age groups (p = 0.01). Overall outcome, assessed using the Glasgow Outcome Scale at 3 months post-SAH, was poorer with advancing age (p < 0.001). Multivariate analysis of overall outcome, adjusting for the different prognostic factors, did not remove the age effect, which suggests that the aging brain has a less optimal response to the initial bleeding. Age as a risk factor is a continuum; however, there seems to be a significant increased risk of poor outcome after the age of 60 years.

Adult↗

PubMed1995

Medical complications of aneurysmal subarachnoid hemorrhage: a report of the multicenter, cooperative aneurysm study. Participants of the Multicenter Cooperative Aneurysm Study.

OBJECTIVES: This report examines the frequency, type, and prognostic factors of medical (nonneurologic) complications after subarachnoid hemorrhage in a large, prospective study. The influences of contemporary neurosurgical, neurological, and critical care practice on mortality and morbidity rates after aneurysmal subarachnoid hemorrhage are evaluated. DESIGN: A study of medical complications observed in the placebo limb of a large, randomized, controlled trial of the calcium antagonist, nicardipine, after subarachnoid hemorrhage. SETTING: Patients were recruited from 50 hospitals in 41 neurosurgical centers in the United States and Canada. PATIENTS: A total of 457 patients with subarachnoid hemorrhage, > or = 18 yrs of age, were randomly assigned to the placebo group. All patients arrived at the participating center within 7 days (mean 1.0 +/- 1.8 [SD] days) of rupture of an angiographically documented saccular aneurysm. MEASUREMENTS AND MAIN RESULTS: The frequency rates of symptomatic vasospasm, rebleeding, and total mortality rate after subarachnoid hemorrhage at 3-month follow-up were 46%, 7%, and 19%, respectively. The frequency of having at least one severe (life-threatening) medical complication was 40%. The proportion of deaths from medical complications was 23%. This value was comparable with the proportion of deaths attributed to the direct effects of the initial hemorrhage (19%), rebleeding (22%), and vasospasm (23%) after aneurysmal rupture. The frequency of life-threatening cardiac arrhythmias was 5%; less ominous rhythm disturbances occurred in 30% of the patients. There was an increased frequency of cardiac arrhythmias on the day of, or day after, aneurysm surgery. Pulmonary edema occurred in 23% of the patients, with a 6% occurrence rate incidence of severe pulmonary edema. There was a wide variation from center to center, with the greatest frequency on days 3 through 7. There was a nonsignificant association of pulmonary edema with the use of hypertensive hypervolemic therapy (p = .10), and a significant association with the timing of surgery (p < .05). Some degree of hepatic dysfunction was noted in 24% of patients, the majority with only mild abnormalities of hepatic enzymes with no clinical accompaniment (4% frequency of severe hepatic dysfunction). Thrombocytopenia occurred in 4% of patients, usually in the setting of sepsis. Renal dysfunction was reported in 7% of the patients, with 15% of that figure deemed to be of life-threatening severity. There was an association (p = .001) with antibiotic therapy. CONCLUSIONS: Potentially preventable medical complications after ruptured cerebral aneurysm add to the total mortality rate of patients, and may increase length of hospital stay in the critical care setting. The proportion of deaths after subarachnoid hemorrhage from medical complications equals those deaths from either direct effects, rebleeding, or vasospasm individually. Pulmonary complications are the most common nonneurologic cause of death. Cardiac arrhythmia, although frequent, was not associated with significant mortality. The frequency of cardiac arrhythmia and pulmonary edema increased on the day of, or day after, aneurysm surgery. Renal and hepatic dysfunction, and blood dyscrasias, were also observed, underscoring the need for meticulous monitoring for metabolic and hematologic derangements.

Adult↗

PubMed1994

Computed tomography versus magnetic resonance imaging in stereotactic localization.

Neurosurgeons are often faced with a lesion that is obvious on magnetic resonance imaging (MRI), but not well-defined on computerized tomography (CT). However, questions remain regarding the distortion inherent in MRI images. Therefore the following comparative study was conducted. Five patients with intracranial lesions (1 lymphoma, 1 multiple sclerosis, 2 glioblastomas, and 1 AVM), underwent both CT and MRI for purpose of stereotactic biopsy or radiosurgery. The Brown-Roberts-Wells CT and MRI compatible localizing rings were used. Coordinates of the left optic nerve-globe junction, the aqueduct, pineal and optic chiasm were recorded from both CT and MRI. With MRI, all three imaging planes, axial, coronal and sagittal, were used. Coordinates were calculated in millimeters and submitted to statistical analysis using Pierson correlation coefficients. In all, there were 17 CT, 17 MRI axial, 13 MRI coronal, and 13 MRI sagittal coordinates. The analysis revealed that of the MRI coordinates, the axial coordinates were more available and retrievable. Lateral targets, such as the left optic nerve-globe junction, were more difficult to identify on coronal and sagittal images and often lacked a full compliment of fiducial points for calculation. The correlation with CT was best for axial, followed by coronal and then sagittal MRI planes. Geometric image distortion occurs owing to nonlinearity of the magnetic field as well as magnet susceptibility to different tissues at an interface. We feel that MRI stereotaxy can be utilized in conjunction with CT for verification of lesion coordinates in relatively large lesions, and particularly in those not well delineated on CT.

Adult↗

PubMed1994

Prognosis of young adults with ischemic stroke. A long-term follow-up study assessing recurrent vascular events and functional outcome in the Iowa Registry of Stroke in Young Adults.

BACKGROUND AND PURPOSE: Information about the long-term prognosis of young adults with ischemic stroke is limited. Therefore, we performed a follow-up assessment of 296 patients with ischemic stroke who are enrolled in the Iowa Registry of Stroke in Young Adults. We studied young adults (age, 15 to 45 years) who were referred to a tertiary medical center for management of ischemic stroke between July 1, 1977, and January 1, 1992. METHODS: Follow-up assessments were performed by means of questionnaires, examinations, telephone interviews, review of medical records, and reports from personal physicians. Data about risk factors, coincident medical diseases, etiology of stroke, treatment, recurrent stroke, other vascular events, and deaths were collected. Outcomes were rated with the Glasgow Outcome Scale, Barthel Index, National Institutes of Health stroke scale, and the Mini-Mental State Examination. Quality of life was assessed with the SF-36 Health Status questionnaire. RESULTS: Follow-up information about the status of 10 patients was limited except that they were alive. Twenty-one patients (7%) died as the result of their initial stroke, and another 40 patients (14%) died during a mean follow-up of 6.0 years. None of the patients aged 25 years or younger at the time of stroke died during follow-up. Mortality was significantly higher among patients who had a stroke secondary to large-vessel stroke and it was significantly lower in patients with stroke of unknown etiology than in patients with stroke of other causes (relative risk [RR], 1.7; 95% confidence limits [CL], 1.0 to 2.7; and RR, 0.1; CL, 0 to 0.6; respectively). Recurrent strokes occurred in 23 patients (9%) and were fatal in 9. Another 37 patients were treated by a cardiologist during follow-up; 3 had had a myocardial infarct. Fourteen additional patients needed major vascular surgery. Outcomes with the Glasgow Outcome Scale and Barthel Index were generally favorable. Still, only 49% of patients were still alive, were not disabled, had not suffered from recurrent vascular events, or had not undergone major vascular surgery. Only 42% of survivors had returned to work. A majority of survivors reported emotional, social, or physical residuals that lessened the quality of life. CONCLUSIONS: The risks of recurrent vascular events in young adults who have had ischemic stroke are considerable. In addition, a majority of survivors will have residual emotional, social, or physical impairments that hamper employment or lower the quality of life. Further research on the quality of life for young adults who survive stroke is needed.

Adolescent↗

PubMed1994

Study designs and potential biases in sports injury research. The case-control study.

Several different epidemiological study designs can be used for aetiological investigations of potential risk factors for the occurrence of sports injuries. The case-control study is an example of a retrospective design in which the investigator starts with the classification of injury status (case or control) and obtains information regarding prior exposure to risk factors. Several decisions need to be made when designing case-control studies. Firstly, the source of the study participants needs to be considered. Cases and controls need to be identified from the same source, i.e. same sport or clinic. Secondly, the same eligibility criteria need to be applied to potential cases and controls. Thirdly, when an injury occurred must be established. The fourth issue concerns the status of cases (incident or prevalent cases). Finally, the number and size of the control groups needs to be determined. Strengths of the case-control study design are the high level of information obtained, the relatively low cost and its usefulness for studying rare sports injuries. The higher susceptibility to bias is one of the limitations of case-control studies. Bias in a case-control study can lead to over or underestimation of the true association between an alleged risk factor and the occurrence of sports injuries. Three types of bias have been distinguished: (i) selection bias; (ii) information bias; and (iii) confounding. Furthermore, the applicability of this type of design is limited to risk factors that remain relatively stable after the occurrence of an injury. The effect of changeable risk factors, such as quadriceps strength and range of motion, is difficult to assess since in many cases data at the time of injury are unavailable.

Athletic Injuries↗

PubMed1994

A randomized trial of two doses of nicardipine in aneurysmal subarachnoid hemorrhage. A report of the Cooperative Aneurysm Study.

High-dose intravenous nicardipine has been shown to reduce the incidence of angiographic and symptomatic vasospasm in patients with aneurysmal subarachnoid hemorrhage (SAH), but treatment may be complicated by side effects, including hypotension or pulmonary edema/azotemia. From August, 1989, to January, 1991, 365 patients at 21 neurosurgical centers were entered into a randomized double-blind trial comparing high-dose (0.15 mg/kg/hr) nicardipine with a 50% lower dose (0.075 mg/kg/hr) administered by continuous intravenous infusion for up to 14 days following SAH. Patients in all neurological grades were eligible for the study. During the study period, 184 patients were randomly assigned to receive high-dose nicardipine and 181 to receive the low dose. There were no significant differences in patient age, admission neurological condition, or amount and distribution of blood clot on initial computerized tomography scan. Patients in the high-dose group received a significantly smaller proportion of the planned dose than those in the low-dose group (80% +/- 0.2% vs. 86% +/- 0.2%, p < 0.05), largely because of premature treatment termination after adverse medical events. The incidence of symptomatic vasospasm was 31% in both groups, and the overall 3-month outcomes were nearly identical. These data suggest that, from a clinical standpoint, the results of high-dose and low-dose nicardipine treatment are virtually equivalent, but administration of low-dose nicardipine is attended by fewer side effects.

Adult↗

PubMed1993

A randomized controlled trial of high-dose intravenous nicardipine in aneurysmal subarachnoid hemorrhage. A report of the Cooperative Aneurysm Study.

Because of their action as cerebral vasodilators, dihydropyridine calcium antagonists have received intense scrutiny for their potential benefit in ameliorating the devastating consequences of delayed cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH). From October, 1987, to September, 1989, 41 North American neurosurgical centers in the Cooperative Aneurysm Study accrued 906 patients with recent (Days 0 to 7) aneurysmal SAH into a prospective randomized double-blind placebo-controlled trial of high-dose intravenous nicardipine to test whether treatment with this agent improved overall outcome. Eligible patients received 0.15 mg/kg/hr of either nicardipine or placebo by continuous infusion for up to 14 days following hemorrhage. The 449 patients randomly assigned to the nicardipine-treated group and the 457 patients assigned to the placebo-treated group were balanced with regard to prognostic factors for ischemic deficits from vasospasm and for overall outcome. Other medical and surgical interventions were used with similar frequency in both groups, except that antihypertensive agents were used less frequently in the nicardipine-treated patients (26% of the nicardipine-treated group vs. 43% of the placebo-treated group, p < 0.001), and more patients in the placebo-treated group had intentional hypervolemia, induced hypertension, and/or hemodilution administered therapeutically for symptomatic vasospasm (38% of the placebo-treated group vs. 25% of the nicardipine-treated group, p < 0.001). The incidence of symptomatic vasospasm during the treatment period was higher in the placebo-treated group (46%) than in the nicardipine-treated group (32%) (p < 0.001). Despite the reduction in symptomatic vasospasm in the nicardipine-treated group, overall outcome at 3 months was similar between the two groups. Fifty-five percent of nicardipine-treated patients were rated as having a good recovery according to the Glasgow Outcome Scale at follow-up review and 17% were dead, compared to 56% and 18%, respectively, in the placebo-treated group (not statistically significant). These data suggest that high-dose intravenous nicardipine treatment is associated with a reduced incidence of symptomatic vasospasm in patients with recent aneurysmal SAH, but not with an improvement in overall outcome at 3 months when compared to standard management in North America. It is postulated that, while nicardipine prevents vasospasm, hypertensive/hypervolemic therapy may be effective in reversing ischemic deficits from vasospasm once they occur.

Adult↗