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Biomedical subjects

E B Larson

Publications and source records attributed to E B Larson.

At least 181 records · Page 10Linked to original sources
PubMed1988

Magnetic resonance imaging of the brain and spine. Is clinical efficacy established after the first decade?

STUDY OBJECTIVE: Evaluation of demonstrated clinical efficacy of magnetic resonance (MR) imaging in the central nervous system. DESIGN: Information synthesis of studies before January 1987. SETTING: Reports were classified by the level of clinical efficacy studied (technical capacity, diagnostic impacts, and therapeutic or patient outcome impacts) and were judged by the validity of their methods, especially avoidance of diagnosis review, test review, and work-up biases. MAIN RESULTS: Magnetic resonance imaging probably is superior to computed tomography for detection and characterization of posterior fossa lesions and spinal cord myelopathies, imaging in multiple sclerosis, detecting lesions in patients with refractory partial seizures, and detailed display for guiding complex therapy, as for brain tumors. In other diseases, the efficacy of MR imaging is similar to that of computed tomography (cerebrovascular, radiculopathy, and infection). Magnetic resonance imaging is less invasive than intrathecal or intravenous contrast-enhanced computed tomography and costs 20% to 300% more than computed tomography, although avoidance of hospital stays may offset some costs. Generally, the quality of MR images probably exceeds that of computed tomographic (CT) scans. However, published evidence does not show that the clinical efficacy of MR imaging is generally superior to that of existing imaging modalities such as computed tomography. Only six studies avoided major methodologic biases, and lower true-positive rates for MR imaging were reported in these studies than reported in multiply biased studies. Few studies of the potential of MR imaging for false-positive diagnosis have been done. CONCLUSIONS: Use of standards for quality of evidence leads to more conservative conclusions than those of reports describing the clinical potential of MR imaging. Some applications of MR imaging were confirmed by rigorous studies, whereas others were not well supported by reports free of methodologic biases. If the diagnostic alternative is invasive (for example, myelography and cisternography), MR imaging is preferred, but adequate diagnosis for many conditions (head trauma, simple stroke, and dementia) may not require the detail of an MR imaging study. In general, more rigorous clinical research studies are needed for new technologies such as MR imaging. Because the field of MR imaging is changing, review of its clinical efficacy will need to be revised frequently.

Adult↗
PubMed1988

Health promotion and disease prevention in the older adult.

Lengthened life expectancy, along with the increased chance that much time in late life may be spent with disabilities and terminal dependency, suggests the need for increased efforts in health promotion and disease prevention in elderly persons. Both goals can be achieved, partly through programs that stress both screening and early detection of some diseases, such as cancer, and decreasing the risk factors of others, such as hypertension, heart disease, and stroke. Efforts also need to be addressed at other common sources of disability and dysfunction like osteoporosis, falls, and fractures. Exercise is an important factor in such programs in order to extend active life expectancy and enhance vigor in later life. Habitual exercise is, however, one of the least prevalent of all the health promotion activities. A carefully designed exercise program that includes education about the reasons for exercise, as well as the proper methods of exercise, could considerably change the health profile of the individual patient and the increasing population over age 65 in this country.

Aged↗
PubMed1987

Falls and fractures in patients with Alzheimer-type dementia.

The prevention of fall-related injuries in patients with Alzheimer-type dementia (ATD) is hampered by an incomplete understanding of their causes. We studied falls and fractures in 157 ATD patients, including 117 with three-year follow-up. Initially all but one patient could walk; 31% reported falls. During follow-up, 50% either fell or became unable to walk. The fracture rate during follow-up (69/1000/y) was more than three times the age- and sex-adjusted fracture rate in the general population. Features of both ATD and comorbid conditions contributed to the risk of falls and fractures. In particular, patients who experienced toxic reactions to drugs on entry into the study were more likely to report they had fallen prior to entry (odds ratio, 4.9; 95% confidence interval, 1.78 to 13.3), and patients who wandered were more likely to sustain fractures (odds ratio, 3.6; 95% confidence interval, 1.25 to 10.4) during the follow-up period, including hip fractures for which the odds ratio of 6.9 (95% confidence interval, 1.66 to 28.6) was unexpectedly high. Preventive measures may be possible, including controlling wandering, avoiding toxic reactions to drugs, and treating comorbid illnesses.

Accidental Falls↗
PubMed1987

A randomized trial of dexamethasone and acetazolamide for acute mountain sickness prophylaxis.

Forty-seven climbers participated in a double-blind, randomized trial comparing acetazolamide 250 mg, dexamethasone 4 mg, and placebo every eight hours as prophylaxis for acute mountain sickness during rapid, active ascent of Mount Rainier (elevation 4,392 m). Forty-two subjects (89.4 percent) achieved the summit in an average of 34.5 hours after leaving sea level. At the summit or high point attained above base camp, the group taking dexamethasone reported less headache, tiredness, dizziness, nausea, clumsiness, and a greater sense of feeling refreshed (p less than or equal to 0.05). In addition, they reported fewer problems of runny nose and feeling cold, symptoms unrelated to acute mountain sickness. The acetazolamide group differed significantly (p less than or equal to 0.05) from other groups at low elevations (1,300 to 1,600 m), in that they experienced more feelings of nausea and tiredness, and they were less refreshed. These drug side effects probably obscured the previously established prophylactic effects of acetazolamide for acute mountain sickness. Separate analysis of an acetazolamide subgroup that did not experience side effects at low elevations revealed a prophylactic effect of acetazolamide similar in magnitude to the dexamethasone effect but lacking the euphoric effects of dexamethasone. This study demonstrates that prophylaxis with dexamethasone can reduce the symptoms associated with acute mountain sickness during active ascent and that acetazolamide can cause side effects that may limit its effectiveness as prophylaxis against the disease.

Acetazolamide↗
PubMed1987

Correlations of Mini-Mental State and modified Dementia Rating Scale to measures of transitional health status in dementia.

Information regarding the relationships of the Mini-Mental State (MMS) and a modified Dementia Rating Scale (mDRS) to measures of change, that is, "transitional" health status, in dementia would be potentially useful in the evaluation and care of demented patients. In a longitudinal study of demented outpatients, MMS and mDRS at entry and at 1- to 2-year follow-up were significantly correlated with five measures of physician- and advocate-rated transitional health status and change in living arrangement during this interval (p less than .01). MMS and mDRS at follow-up also predicted mortality during a subsequent year of follow-up (p less than .01). Estimated change in MMS and mDRS was significantly correlated with all transition variables, except for MMS and results suggest MMS, mDRS, and estimated change in them reflect these aspects of transitional health status in dementia.

Aged↗
PubMed1987

The frequency of C4B variants of complement in familial and sporadic Alzheimer disease.

A previous study reported an unexpected increased frequency of the uncommon C4B2 allele of complement in a group of patients with senile dementia of the Alzheimer type. We compared the frequency of various C4B types in 25 patients with familial Alzheimer dementia (AD), 22 patients with sporadic AD, and 360 control individuals. Neither Alzheimer group showed any significant increase or decrease in the frequency of C4B alleles compared with controls. We were unable to confirm any association between AD and the C4B2 allele.

Adult↗
PubMed1987

Influenza vaccination in community elderly. A controlled trial of postcard reminders.

Available strategies to increase influenza vaccination rates in the elderly have not been tested in the private sector where most elderly receive care. We performed a randomized controlled trial of a postcard reminder in the three private general internal medicine practices. The observed vaccination rates of 55% in experimental patients (N = 262) and 54% in control patients (N = 278) were similar, though much higher than estimated national rates of 20%. The data indicated that the baseline (control group) vaccination rate was high probably because study participants were exposed to many community vaccination cues, separate from the study cue. That vaccination rates were not higher after additional exposure to the study cue suggests that a "ceiling effect" occurred. Including 70 patients not randomized into the trial because they received flu shots prior to randomization, the vaccination rate in patients who had a clinic visit during autumn months was 75% compared to a rate of 52% in patients not visiting the clinic (P less than .001). Our results suggest that vaccination rates can be considerably higher in the private sector than those reported in the past, and that both vaccination cues and direct patient contact appear important to promote vaccination. This and other studies suggest that traditional cues may have a ceiling effect, yielding vaccination rates no higher than 55 to 65%; further increases in rates will require other approaches.

Aged↗
PubMed1987

Adverse drug reactions associated with global cognitive impairment in elderly persons.

Adverse drug reactions causing cognitive impairment are an important problem in the elderly. Thirty-five patients with adverse drug reaction were identified among more than 300 patients evaluated for cognitive impairment and compared with patients without adverse drug reaction. Sedative hypnotic agents, especially long-acting benzodiazepines, were the commonest drugs associated with cognitive impairment in this population. The number of drugs used, use of sedative hypnotics and antihypertensives, and falling were strongly associated with adverse reactions in logistic regression analyses. The relative odds of an adverse reaction associated with cognitive impairment increased as the number of prescription drugs increased, exceeding 9.0 for patients taking four or more prescription drugs. Adverse drug reactions are an important source of excess morbidity in patients with dementia or suspected dementia. Strategies that could minimize this problem include a high index of suspicion, drug-free trials in suspected cases, and careful monitoring of drug therapy.

Accidental Falls↗
PubMed1987

Health benefits of exercise in an aging society.

The effects of regular aerobic exercise are important to an aging society increasingly preoccupied with exercise. Traditionally, most attention has been directed to the relationship between a physically active life-style and cardiovascular mortality. In an aging society, however, active life expectancy and maintenance of independence may be as important as effects of regular exercise on longevity. Regular exercise results in increased maximum aerobic capacity due to peripheral changes in muscle (increased capacity for aerobic metabolism and improved substrate and oxygen extraction with a widened arteriovenous oxygen difference) and also due to cardiovascular changes with increased stroke volume and cardiac output in normal persons. "Therapeutic benefits" of conditioning probably occur at submaximal work loads common to everyday activity, when cardiac work and myocardial oxygen consumption are less for any given work load, muscles are more efficient, and relative oxygen requirements are less. Aging is associated with a linear decline in maximum aerobic capacity. The rate of decline is twofold greater when comparing sedentary with physically active middle-aged men. Thus, regular exercise could conceivably lower functional aerobic age by slowing this functional decline. Exercise, particularly excessive exercise, is also associated with serious hazards, including sudden death, nonfatal myocardial infarction, excessive fatigue, hyperthermia, and significant musculoskeletal problems. Accounts of the health effects of exercise should consider a wide range of risks and benefits, especially those related to improving function, minimizing disability, and prolonging independent living.

Aging↗
PubMed1987

A randomized trial of electronic fetal monitoring in preterm labor.

Intrapartum electronic fetal heart rate (FHR) monitoring and fetal blood gas sampling were compared with periodic auscultation of FHR in a multicentered randomized trial of preterm singleton pregnancies with fetal weights of 700-1750 g. Two hundred forty-six pregnancies were studied (electronic FHR monitoring N = 122, auscultation N = 124). Perinatal or infant death was associated with 14% of pregnancies with electronic FHR monitoring and 15% with auscultation. No significant differences were noted in the prevalence of low five-minute Apgar scores, intrapartum acidosis, intracranial hemorrhage, or frequency of cesarean section (P greater than .10). Compared with electronic FHR monitoring, intrapartum auscultation as done in this study is unlikely to be associated with detectable differences in perinatal outcomes within the high-risk setting of preterm labor.

Apgar Score↗
PubMed1987

An outpatient geriatric psychiatry assessment and treatment service.

An outpatient evaluation and treatment program for cognitively impaired elderly and their families opened at the University of Washington in 1978. The multidisciplinary approach includes psychiatric, medical, psychological, social, and environmental assessments. The program has been well received by the public and has served as a model for similar programs elsewhere. An important finding from the clinic has been to demonstrate the high frequency of excess disability in patients with dementia of the Alzheimer's type.

Aged↗
PubMed1986

Hearing impairment and cognitive decline in senile dementia of the Alzheimer's type.

Hearing impairment has been hypothesized as contributing to symptoms of dementia. Data from a longitudinal study were analyzed to determine if auditory status predicted cognitive functional decline in senile dementia of the Alzheimer's type (SDAT). As part of a larger study, 156 consecutive SDAT outpatients had received a comprehensive medical evaluation including baseline screening for hearing impairment with the finger friction test and serial assessment of cognitive function with the Mini-Mental State examination. Age and cognitive function at entry to the study were greater among individuals with impaired hearing (N = 36) than with normal hearing (N = 120). The demographic profiles of the impaired and normal hearing groups were otherwise similar, as was the prevalence of depression. Intervening mortality rates were nearly identical. Decline in cognitive function one year later, however, was nearly twice as great in the impaired hearing group, a statistically significant difference (P less than .05, by one-tailed t test) even when controlled for age and initial cognitive function. These results, which need to be verified with sophisticated audiometric techniques, suggest that hearing impairment may be a prognostic indicator for subsequent cognitive dysfunction in SDAT. They are consistent with the hypothesized relationship between hearing impairment and dementia in SDAT as well as alternative hypotheses discussed in the text.

Aged↗