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Biomedical subjects

E B Larson

Publications and source records attributed to E B Larson.

At least 73 records · Page 4Linked to original sources
PubMed1997

The Kinmen Neurological Disorders Survey (KINDS): a study of a Chinese population.

We conducted an epidemiological study of several neurological disorders among the Chinese aged 50 years or older on the islet of Kinmen. All participants were interviewed and examined by neurologists. From the targeted population of 5,061 individuals, 3,915 (77.4%) of them completed the evaluations. Among the 4,087 individuals with whom face-to-face contact was made, the refusal rate was 4.2%. The disorders of interest were dementia, Parkinson's disease, essential tremor, stroke, transient ischemic attacks, and migraine. Among the 3,915 participants, 366 cases were found with 1 or more of the surveyed neurological disorders on the prevalence day, August 1, 1993, yielding a prevalence of 93.5/1,000. The purpose of this study, the general methodology, and some overall findings are presented in this communication in order to provide a common background for detailed findings on each disorder to be reported separately.

Age Factors↗
PubMed1997

Alzheimer's disease and history of blood transfusion by apolipoprotein-E genotype.

Some dementias, such as Creutzfeldt-Jakob disease, may result from transmissible agents. To assess the possibility of a blood-borne transmissible agent in Alzheimer's disease (AD), we compared informant-reported history of blood transfusions among 326 newly recognized probable AD cases and 330 control subjects of similar age and sex, randomly selected from the same health maintenance organization population. Since risk of AD is increased in persons with apolipoprotein E epsilon 4 (APOE-e4) alleles, we examined whether the transfusion-AD relationship varies by APOE genotype. Transfusion was more frequent among controls (17.9%) than cases (12.0%) in the overall group (crude odds ratio = 0.62; 95% confidence interval = 0.40, 0.97). Similar risks were seen for transfusions occurring < or = or > 10 years before the reference year. Stratified analysis by APOE-e4 genotype showed no effect modification. Logistic regression adjusting for age, sex, education, and presence of e4 did not change the transfusion-AD association. We conclude that a history of blood transfusion is not associated with increased risk of AD, nor does consideration of APOE-e4 status modify that conclusion.

Aged↗
PubMed1996

Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state. The Kame Project.

Studies of Asian populations generally have reported prevalence rates for dementia similar to those of predominantly Caucasian populations, but relative prevalence rates of Alzheimer's disease and vascular dementia have differed. Between May 1, 1992 and May 1, 1994, the prevalence rates of dementia, Alzheimer's disease, and vascular dementia were examined in the Japanese American population aged over 65 years in King County, Washington State. A total of 3,045 eligible individuals were identified in a census of persons who were of at least 50% Japanese heritage. Of 1,985 persons who participated in the baseline examination, 382 individuals of 450 sampled from all cognitive performance strata received a diagnostic evaluation. A total of 107 cases with a Clinical Dementia Rating (CDR) of > or = 1 met criteria for dementia according to the Diagnostic and Statistical Manual, 3rd edition, revised (DSM-III-R); 58 of these cases were diagnosed with Alzheimer's disease and 24 with multi-infarct dementia. The estimated prevalence rate for all dementias was 6.3% (95% confidence interval 5.9-6.8). Prevalence rates for dementia increased continuously with age and were 30%, 50%, and 74% for participants aged 85-89, 90-94, and > or = 95 years, respectively; for Alzheimer's disease, prevalence rates were 14%, 36%, and 58% for these three age groups. Rates for Alzheimer's disease were generally higher among women; for multi-infarct dementia, rates for men and women were similar. In the institutional population, the prevalence rate was 66%, and in the community, 2.9%. Persons with lower education had higher overall rates of dementia than those with higher education, but this tendency became weak and inconsistent when rates were age-stratified. The prevalence of dementia in this geographically defined population of Japanese Americans was somewhat higher than prevalence rates reported from Japan, and the distribution of dementia subtypes more closely resembled that found in Caucasian populations in North America and Europe than previously reported in Asian populations.

Age Distribution↗
PubMed1996

Effect of estrogen replacement therapy on the specificity and sensitivity of screening mammography.

BACKGROUND: Previous studies have demonstrated that mammographic breast density increases following the initiation of estrogen replacement therapy (ERT). The effect, if any, that this increase in density has on the specificity (related to false-positive readings) and the sensitivity (related to false-negative readings) of screening mammography is unknown. PURPOSE: Using a retrospective cohort study design, we assessed the effects of ERT on the specificity and the sensitivity of screening mammography. METHODS: Participants (n = 8779) were postmenopausal women, aged 50 years or older, who were enrolled in a health maintenance organization located in western Washington state and who entered a breast cancer screening program between January 1988 and June 1993. Two-view mammography was performed as part of a comprehensive breast cancer screening visit. Menopausal status, as well as demographic and risk-factor information, was recorded via self-administered questionnaires. Hormonal replacement therapy type and use were determined from questionnaire data and from an automated review of pharmacy records. Individuals diagnosed with breast cancer within 12 months of their first screening-program mammograms were identified through use of a regional cancer registry. Risk ratios (RRs) plus 95% confidence intervals (CIs) of false-positive as well as false-negative examinations among current and former ERT users (with never users as the reference group) were calculated. Reported P values are two-sided. RESULTS: The specificity of mammographic screening was lower for current users of ERT than for never users or former users. Defining a positive mammographic reading as any non-normal reading (either suspicious for cancer or indeterminate), the adjusted RR (95% CI) of a false-positive reading for current users versus never users was 1.33 (1.15-1.54) (P < .001); for former users versus never users, the RR (95% CI) was 1.00 (0.87-1.15). The adjusted mammographic specificities (95% CIs) for never users, former users, and current users of ERT were 86% (84%-88%), 86% (84%-87%), and 82% (80%-84%), respectively. Defining a positive reading more rigorously (i.e., as suspicious for cancer only), the adjusted RRs (95% CIs) of false-positive readings for current users and former users (versus never users) were 1.71 (1.37-2.14) (P < .001) and 1.16 (0.93-1.45), respectively. Sensitivity was also lower in women currently receiving ERT. The unadjusted RR (95% CI) of a false-negative reading for current users versus never users was 5.23 (1.09-25.02) (P = .04); for former users versus never users, the RR (95% CI) was 1.06 (0.10-10.87). The unadjusted mammographic sensitivities (95% CI) for never users, former users, and current users of ERT were 94% (80%-99%), 94% (69%-99%), and 69% (38%-91%), respectively. CONCLUSIONS AND IMPLICATIONS: Current use of ERT is associated with lower specificity and lower sensitivity of screening mammography. Lower specificity could increase the cost of breast cancer screening, and lower sensitivity may decrease its effectiveness.

Aged↗
PubMed1996

Cost-effectiveness of lumbar discectomy for the treatment of herniated intervertebral disc.

STUDY DESIGN: A cost-effectiveness analysis of lumbar discectomy based on existing efficacy data and newly gathered cost data. OBJECTIVES: For patients with herniated lumbar discs unresponsive to conservative management, surgery relieves pain more rapidly but at higher costs than continued medical therapy. We evaluated the cost-effectiveness of lumbar discectomy for these patients. SUMMARY OF BACKGROUND DATA: Effectiveness estimates were based on the results of a published trial of 126 herniated disc patients randomized to surgical or nonsurgical treatment. Quality of life values were based on a study of 83 subjects with low back pain. Treatment costs for herniated discs were estimated from insurance data for 372 patients treated surgically and 1,803 treated medically. METHODS: Efficacy results were weighted by quality of life values to estimate the quality-adjusted benefit of surgery. Cost-effectiveness was calculated in dollars per quality-adjusted year of life gained. Supplemental data sources for cost and effectiveness provided ranges for sensitivity analyses. RESULTS: Surgery increased average quality-adjusted life expectancy by 0.43 years during the decade following treatment, a benefit similar to extending a healthy life by 5 months. Reimbursements for surgical patients were $12,550 more than for medical patients. Nondiscounted and 5% discounted cost-effectiveness were $29,200 and $33,900 per quality-adjusted year of life gained. Supplemental analyses confirmed the basecase effectiveness estimates but suggested that the cost of discectomy was overestimated. Replacing the main cost estimate with one based on HMO patients lowered discectomy's cost to $12,000 per quality-adjusted life-year gained. CONCLUSION: For carefully selected patients with herniated discs, surgical discectomy is a cost-effective treatment. Discectomy's favorable cost-effectiveness results from its substantial effect on quality of life and moderate costs.

Cost-Benefit Analysis↗
PubMed1996

A door-to-door survey of Parkinson's disease in a Chinese population in Kinmen.

BACKGROUND: Most published studies have shown lower prevalence rates of Parkinson's disease (PD) in Asian and black African than in Western countries, leading to the hypothesis that Asians and blacks might be protected from PD. OBJECTIVE: To investigate the prevalence of PD in a Chinese population. DESIGN: Community-based survey. SETTING: Registered residents 50 years of age or older (N = 5061) on the islet of Kinmen located off the southeastern coast of China [corrected]. METHOD: Single-phase door-to-door survey by neurologists. All participants were administered a questionnaire and received motor examinations of the Unified Parkinson's Disease Rating Scale. RESULTS: The participation rate was 96% (N = 3915) among 4158 contacted individuals. Twenty-three cases of PD were identified, including three cases with dementia. The crude prevalence rate of PD was 587 (95% confidence interval (CI), 373 to 884) per 100,000 persons 50 years of age or older. Assuming no case of PD among individuals under 50 years of age, the prevalence rate was 119 (95% CI, 80 to 169) per 100,000 for the total population. CONCLUSIONS: The prevalence rates of PD in Kinmen were much higher than those reported from mainland China, but slightly lower than those reported from more developed countries. The present findings suggest that, instead of genetic factors, differences in case-ascertainment, life expectancy, and the length of survival with PD may be more important contributors to the variations in observed PD prevalence rates.

Aged↗
PubMed1996

Apolipoprotein E in Alzheimer's disease risk and case detection: a case-control study.

The objective of this study was to describe the association between the epsilon 4 allele of the apolipoprotein E gene (APOE E4) and Alzheimer's disease (AD) and to evaluate APOE E4 genotyping as a test for AD. The study base of this case-control study included about 23,000 persons 60 year of age or greater (a large health maintenance organization); the demographic characteristics of this group are similar to those of the surrounding area. Analysis focused on 234 Caucasian probable AD patients first identified between 1987 and 1993; and 304 cognitively intact controls of similar age, sex, and race who were randomly selected from the same study base. All cases were examined and diagnosed by study physicians using standard protocols. All subjects participate in continuing annual follow-up testing to verify their cognitive status. APOE genotypes were determined from blood samples using standard laboratory methods. Subject characteristics and diagnoses were obtained from interviews, diagnostic examination, or medical record review. Heterozygous E4 individuals had a crude odds ratio of 3.1 (2.1-4.5) for AD compared to those with no E4, while homozygous E4 subjects had an odds ratio of 34.3 (8.0-146.3) for AD. As an indicator of AD, having one E4 allele showed a sensitivity of 0.52 and a specificity of 0.74. Homozygous E4 genotype had a sensitivity of 0.23 and a specificity of 0.99 (when compared to non-E4 genotypes). Cardiovascular disease differed in cases and controls, but did not confound or modify the APOE E4-AI) association. In this study base, the APOE E4 allele was a significant risk factor. However, considering either homozygous or heterozygous E4 genotype as a screen or diagnostic marker for AD would miss many true cases and could misclassify many normals as AD.

Aged↗
PubMed1996

Skin cancer diagnosis in a primary care setting.

BACKGROUND: Primary care providers are in a good position to detect sk in cancers early, but their current involvement in diagnosis and referral of patients with skin cancer is unknown. Some managed care settings utilize a primary care case manager approach to health care. OBJECTIVE: The purpose of this study was to assess the incidence and demographic associations of skin cancer in a managed care population served by primary care providers. METHODS: this study analyzed 1215 skin biopsy specimens obtained by family physicians, internists, and supervised certified physician assistants within an eastern Washington health maintenance organization and the 69 biopsy specimens obtained by referral specialists and confirmed by pathologic consultation. RESULTS: Internists, family physicians, and their physician assistants performed 94.7% of the biopsies on 87% of all malignancies. Dermatologists and surgeons performed the rest. Primary care providers and dermatologists detected malignant melanomas at a rate comparable to a similar study from British Columbia but lower than other previous investigations. CONCLUSION: Melanomas were diagnosed in this managed care system at a rate comparable to a similar system in Canada. Lower rates for other skin cancers are probably because of methodologic differences from other studies, but variation in histologic diagnoses between pathologists and differences in skin cancer detection cannot be excluded.

Adult↗
PubMed1996

Evidence for a non-linear relationship between leg strength and gait speed.

Although the relationship between strength and physical performance in older adults is probably non-linear, few empirical studies have demonstrated that this is so. In a population-based sample of adults aged 60-96 years (n = 409), leg strength was measured in four muscle groups (knee extensor, knee flexor, ankle plantar flexor, ankle dorsiflexor) of both legs using an isokinetic dynamometer. A leg strength score was calculated as the sum of the four strength measurements in the right leg. Usual gait speed was measured over a 15.2 metre course. With a linear model, leg strength explained 17% of the variance in gait speed. Non-linear models (quadratic and inverse) explained significantly more variance (22%). The nature of the non-linear relationship was that, in stronger subjects, there was no association between strength and gait speed, while in weaker subjects, there was an association. Body weight and age also explained significant amounts of variance in gait speed, while sex and height did not. The results supported the hypothesis of a non-linear relationship between leg strength and gait speed that is similar for older men and women. This finding represents a mechanism for how small changes in physiological capacity may have substantial effects on performance in frail adults, while large changes in capacity have little or no effect in healthy adults.

Adult↗
PubMed1996

Neuropathologic diagnostic outcomes from a cohort of outpatients with suspected dementia.

BACKGROUND: Researchers, clinicians, patients, and families need to know the accuracy of clinical dementia diagnoses. METHODS: A prospective cohort of outpatients presenting with complaints of cognitive impairment to a geriatric clinic was established from 1978 to 1982. All patients initially received a standardized clinical evaluation and then were followed longitudinally. RESULTS: Of 304 patients originally enrolled, 72 have come to autopsy and neuropathologic evaluation. Of those patients, 56 had been clinically diagnosed with Alzheimer's disease (AD) and 16 had been diagnosed with other conditions. The sensitivity, specificity, and diagnostic accuracy of the clinical diagnosis of AD compared with neuropathologic diagnosis was 95%, 81%, and 92%, respectively. CONCLUSION: Our findings support the conclusion that the practicing clinician using standardized clinical criteria can accurately diagnose AD approximately 90% of the time. These data may also be useful in the planning of future care of the AD patient.

Aged↗
PubMed1996

Prevention of Alzheimer disease: a perspective based on successes in the prevention of other chronic diseases.

Alzheimer disease, like other common chronic diseases, likely has genetic and environmental risk factors. Prevention of arteriosclerotic vascular disease has occurred based on efforts to reduce risk factors demonstrated in epidemiologic and more basic science research. At present, there are no known risk factors for Alzheimer disease which could form the basis of a preventive strategy. To make progress in the prevention of Alzheimer disease, new findings from epidemiology and basic science will be needed. The current state of the art of epidemiologic studies of dementia is well enough developed to test credible hypotheses. The availability of reliable biomarkers along with cooperative efforts between molecular biologists and clinical epidemiologists should allow us to pursue promising fields in clinical research.

Alzheimer Disease↗
PubMed1996

Impact of sample selection on APOE epsilon 4 allele frequency: a comparison of two Alzheimer's disease samples.

OBJECTIVE: In a highly selected sample of unrelated Alzheimer's disease (AD) patients, we found that the APOE epsilon 4 allele frequency was higher than previously reported. Differing selection and ascertainment criteria may lead to these differences. To address this possibility, we compared the epsilon 4 allele frequency in two samples of AD patients selected from the same geographical area. SETTING AND PARTICIPANTS: Cases (n = 55) and controls (n = 99) from a research clinic-based sample were compared with subjects (n = 537) from a community-based AD patient sample. The samples consisted of unrelated cases who met NINCDS/ADRDA criteria for probable AD. DESIGN AND MEASUREMENTS: Clinical characteristics and APOE genotype data were obtained from AD cases and controls from both samples. RESULTS: Frequency of APOE epsilon 4 allele in the research cases compared with the community cases (0.45 vs 0.36) was nearly significant. We compared demographic and clinical characteristics that might account for this difference and found that the research cases were younger, had an earlier age of onset, and had more advanced disease than the community cases. After onset age was controlled, there was no overall difference between epsilon 4 allele frequency of the two samples. CONCLUSIONS: We found that the epsilon 4 allele frequency tended to be higher in the research AD sample compared the community-based sample. The two samples differed in several demographic and clinical characteristics. We conclude that research-based samples may lead to enrollment of younger patients with more severe disease who have higher APOE epsilon 4 allele load. This potential selection bias must be considered in the interpretation of studies of APOE allele frequency.

Age of Onset↗
PubMed1996

Attitudes toward use of nursing homes and home care in older Japanese-Americans.

OBJECTIVE: A cohort of 1142 older Japanese Americans was identified to study preferences and attitudes regarding use of long-term care (nursing home or home care). DESIGN: Prospective cohort study. PARTICIPANTS AND SETTING: Older Japanese Americans in King County, Washington. RESULTS: Subjects were asked to consider hypothetical situations in which they were temporarily disabled by hip fracture or permanently disabled by dementing illness. If they fractured a hip, only 12% intended to use a nursing home; 29% intended to recover at home with the help of family or friends; another 54% intended to use paid home health care. If they became demented, the majority (53%) intended to use a nursing home; only 11% intended to rely on family or friends for care, and another 29% intended to use paid home health care. Similar responses were observed when subjects were asked what most members of their family or friends would wish them to do; however, they tended to value the perceived wishes of religious figures or the Japanese American community-at-large less than those of family or friends. Significant correlates with intention to enter nursing homes were lack of social support (unmarried, few or no close relatives or housemates), female gender, and high levels of acculturation into American society (never lived in Japan, English-speaking only). Other factors that were not significantly correlated were health perceptions, satisfaction and life control scales, and health care utilization (hospitalizations and MD visits). In multivariate logistic regression, marital status and level of acculturation were the most powerful independent predictors of intention to enter nursing homes. Age and female gender were predictors of intention to use home care. In the base population of subjects, the prevalence of nursing homes use (5%) was similar to that of the general US older population. CONCLUSIONS: We conclude that older Japanese Americans in the Pacific Northwest often intend to enter nursing homes if they became disabled by dementing illness. Actual use is similar to other older populations. This may be attributable largely to the existence of an ethically appropriate nursing home which is strongly supported by, and familiar to, this close-knit community. Intention to use long-term care services appears to be dependent primarily on the level of social supports and acculturation into American society.

Aged↗
PubMed1996

Prevalence of stroke in Kinmen.

BACKGROUND AND PURPOSE: Stroke is the second most common cause of death in Taiwan. We studied its prevalence, risk factors, and mortality in a rural Chinese population. METHODS: A door-to-door survey of stroke was conducted in two Kinmen Island townships with a total population of 26105 people. Our target population (n = 5061) consisted of all the registered residents in these townships who were aged > or = 50 years on August 1, 1993. All participants were given a standardized neurological examination and a questionnaire. RESULTS: The participation rate was 77.4% (n = 3915). Ninety-six cases of completed stroke were identified. Eighty-nine patients had one, 6 patients had two, and 1 patient had three episodes of stroke. The prevalence of stroke in persons aged > or = 50 years was 24.5 per 1000 (95% confidence interval, 19.7 to 29.3 per 1000). Prevalence increased with age. Statistically significant risk factors associated with stroke included hypertension, diabetes mellitus, and irregular heartbeats. Of the stroke survivors, 59% were independent in activities of daily living and 71% could walk independently. CONCLUSIONS: Compared with other countries, Taiwan has a moderately high prevalence of stroke. The risk factors for stroke in this rural region of a developing country are similar to those in developed countries. Most stroke survivors here perform their daily activities independently without outside assistance.

Activities of Daily Living↗