Statistically adjusted estimates of geographic mortality profiles.

The spatial variation of site-specific cancer mortality rates at the county or state economic area level can provide a) insights into possible etiologic factors and b) the basis for more detailed epidemiologic studies. One difficulty with such studies, especially for rare cancer types, is that unstable local area rate estimates, resulting from small population sizes, can obscure the underlying spatial pattern of disease risk. This paper presents a methodology for producing more stable rate estimates by statistically weighting the local area rate estimate toward the experience at the national level. The methodology is illustrated by the analysis of the spatial variation of two cancer types, bladder and lung, for U.S. white males over the three decades 1950-79.

Density profiles of Alzheimer disease regional brain pathology for the huddinge brain bank: pattern recognition emulates and expands upon Braak staging.

Density profiles of Alzheimer's disease (AD) regional brain pathology were constructed for 249 subjects in the Huddinge Brain Bank. Counts per square millimeter for neurofibrillary tangles (NFT), diffuse plaques (DP), and neuritic plaques (NP) in 38 areas were investigated using a pattern recognition technique called GoM. The seven distributional profiles of AD neuropathology emulated and expanded upon Braak staging illustrating induction (Groups 1-3) and clinical progression (Groups 4-7). Normal aging represented limited AD changes, few NFT in the entorhinal cortex and hippocampal CA1 (Group 1). The threshold for possible AD was NFT in the subiculum (Group 2), found with DP in the neocortex. Temporal medial NFT was the threshold for probable AD (Group 4). The 'oldest-old', often demented without brain atrophy, had extensive entorhinal/CA1 NFT and cortical DP, but few cortical NFT or NP (Group 5). A second subtype 'disconnection' (Group 6) lacked AD pathology for a specific set of subcortical and cortical areas. Accumulation of NFT in first-affected areas continued through end-stage disease (Group 7), with apparent rapid transition of DP to NP in the cortex during clinical progression. The evolution of AD is a highly ordered sequential process. Pattern recognition approaches such as GoM may be useful in better defining the process.

Assessment of spatial variation of risks in small populations.

Often environmental hazards are assessed by examining the spatial variation of disease-specific mortality or morbidity rates. These rates, when estimated for small local populations, can have a high degree of random variation or uncertainty associated with them. If those rate estimates are used to prioritize environmental clean-up actions or to allocate resources, then those decisions may be influenced by this high degree of uncertainty. Unfortunately, the effect of this uncertainty is not to add "random noise" into the decision-making process, but to systematically bias action toward the smallest populations where uncertainty is greatest and where extreme high and low rate deviations are most likely to be manifest by chance. We present a statistical procedure for adjusting rate estimates for differences in variability due to differentials in local area population sizes. Such adjustments produce rate estimates for areas that have better properties than the unadjusted rates for use in making statistically based decisions about the entire set of areas. Examples are provided for county variation in bladder, stomach, and lung cancer mortality rates for U.S. white males for the period 1970 to 1979.

Proxy response patterns among the aged: effects on estimates of health status and medical care utilization from the 1982-1984 long-term care surveys.

We examined the use of proxies in samples of persons aged 65 years and over from the 1982 and 1984 National Long-Term Care Surveys (NLTCS). The NLTCS are designed to describe the Medicare-enrolled elderly population, their health and functioning, hospital, home health, and institutional use. The NLTCS, being longitudinal, allows trends in functional and health status to be examined as well as the changing character of community-based and institutional services used by chronically disabled persons aged 65 years and older. In analyses of proxy responses there was little evidence of differences in accuracy between self- and proxy reports in persons with different health and functional characteristics. The amount and type of proxy reporting did depend on the health and functional characteristics of the sample person. The cognitively impaired, and the frail elderly, had high levels of proxy use as well as small differences in the accuracy of reporting service use and program enrollment. The results are consistent with methodological studies of proxy reporting in health surveys of other populations.

The prevalence and 3-year incidence of dementia in older Black and White community residents.

OBJECTIVE: To determine the prevalence and 3-year incidence of dementia in Blacks and Whites age 65 and older in a five-county Piedmont area of North Carolina. DESIGN: Stratified random sample of members of the Duke Established Populations for Epidemiologic Studies of the Elderly (EPESE) (baseline n = 4,136; 55% Black; weighted n = 28,000). Prevalence study members were differentially selected on the basis of score on the Short Portable Mental Status Questionnaire at the second in-person Duke EPESE wave. Incidence study members included all persons with obvious cognitive decline over a 3-year period, and a 10% sample of the remainder. MEASUREMENTS: Self- and informant report on health history, functional status, and memory. Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Neuropsychology Battery administered to all subjects, and CERAD Clinical Battery to those with impaired memory. Clinical consensus to determine presence and type of dementia. RESULTS: Prevalence of dementia for persons > or =68 years old was 0.070 (95% confidence interval = 0.021-0.119) for Blacks and 0.072 (0.022-0.122) for Whites. Rates for Black men (0.078, 0.001-0.155) exceeded those for Black women (0.066, 0.003-0.129), but gender rates for Whites were reversed (men: 0.044, 0.000-0.103), (women: 0.087, 0.015-0.160). Neither race nor gender differences were significant. Prevalence of dementia increased through age 84 and tapered off thereafter. Three-year incidence of dementia was 0.058 (0.026-0.090) for Blacks and 0.062 (0.027-0.097) for Whites. Neither race nor gender differences were significant. Incidence increased through age 84, but moderated thereafter for all but Black men. The proportional representation of different types of dementia varied little by race. CONCLUSION: Prevalence, 3-year incidence, and types of dementia are comparable in Black and White elderly in the Piedmont area of North Carolina.

Trends in US suicide mortality rates 1968 to 1982: race and sex differences in age, period and cohort components.

Interest has recently emerged in increases in suicide among US teenagers. Nonetheless suicide remains one of the major causes of death among the fastest growing components of the US population--the elderly. We examine the trends in US age-specific suicide rates for the period 1962 to 1981 for four elderly race and sex groups. The trends were analysed using a Poisson regression model which isolated the age, period, cohort effects for suicide mortality for demographic groups. Age, period and cohort effects all significantly contributed to these trends. The race and sex differences were largest for the age pattern of changes in suicide mortality. Of particular interest was the different contribution of each of these factors to recent increases in mortality at advanced ages for black males--a hitherto little recognized or studied trend.

Longitudinal models for chronic disease risk: an evaluation of logistic multiple regression and alternatives.

The logistic multiple regression model is often used in the analysis of the relation between chronic disease risk and selected risk factors in longitudinal data. Unfortunately, the logistic function has certain properties that make it inappropriate as a mode of risk analysis for longitudinal studies. The consequences of applying the logistic function to longitudinal data is that the numerical values of logistic regression coefficients cannot be meaningfully compared between studies of different durations. Sample calculations are presented to illustrate the magnitude of the problem for a range of relative study lengths and levels of risk. Two solutions are offered for the problem. First, a series of approximations are derived which permit such comparisons if the studies are not greatly dissimilar in length. Second, if comparisons of the risk coefficients are to be made across studies of greatly dissimilar duration, it is necessary to model risk via an appropriate statistical model. Criteria for assessing the appropriateness of risk functions for the analysis of longitudinal data are proposed and alternatives evaluated.

A dynamic analysis of chronic disease development: a study of sex specific changes in coronary heart disease incidence and risk factors in Framingham.

An analysis of sex differentials in the dynamics of coronary heart disease (CHD) in the Framingham study is conducted using a methodology designed process which aids in the interpretation of the longitudinal results. This methodology permits the analysis of risk variable changes over time to be conducted independently of the analysis of the relation of risk variable values to CHD risk. The independent analyses afford a complete utilisation of information from longitudinal studies of chronic disease risk and produce insights into the dynamics of chronic disease development not available by other analytic strategies. The results of this analysis are compared with results obtained from a similarly structured multiple logistic analysis--a comparison which illustrates some of the technical and conceptual deficiencies of the often employed multiple logistic analysis when applied to longitudinal data.

Predicting 10-year care requirements for older people with suspected Alzheimer's disease.

OBJECTIVE: To describe the types and costs of care received for 10 years after the identification of an older person with suspected Alzheimer's disease (AD) by using data from 3254 patients with suspected AD who participated in the National Long Term Care Survey (NLTCS). METHODS: By using a Markov model derived using grade of membership techniques, the following were determined: survival probabilities at 10 years; years of survival during the 10 years; years in institutions; years with two or more impairments in basic activities of daily living; hours of paid and informal care while the older person lived in the community; and costs of paid community, institutional, and medical care. RESULTS: Greater degrees of cognitive impairment present when AD was identified were associated with reduced predicted probability of surviving 10 years, increased predicted number of years spent in institutions, increased hours of care required while affected individuals remained in the community, and increased costs of paid community, institutional, and medical care. Substantial differences between men and women were seen: severity-adjusted 10-year costs were almost two times higher for women with AD than for men ($75,000 compared with $44,000); according to sensitivity analysis, average 10-year costs might be as high as $109,000 for women and $67,000 for men. CONCLUSIONS: AD imposes a substantial burden on older persons. Interventions that slow the progression of the disease may therefore affect community survival as well as healthcare costs.

Nursing home residents: a multivariate analysis of their medical, behavioral, psychosocial, and service use characteristics.

BACKGROUND: Elderly residents of nursing homes often have multiple comorbidities and functional limitations. The status of 4,525 residents of complex and standard care units in 177 nursing homes where the nursing home was determined to provide adequate care, and from 14 specialized Alzheimer's units, was evaluated on 111 measures of medical condition, functional status, psychological well-being and cognitive performance in a demonstration study assessing quality of care in six states. Detailed measurements were also made of the types and amounts of services used (in minutes per day) by the residents. METHODS: Given the number of health measures, and the possibility of assessment error, a multivariate analytic procedure called Grade of Membership (GoM) was used. This procedure identified profiles of health and functioning measures to identify the characteristics of clinically distinct groups of nursing home residents. RESULTS: The analysis identified 11 profiles of health and functioning characteristics which described the 111 resident measurements. The 11 profiles predicted differentials in nursing home length of stay, and service use by various classes of caregivers. The GoM profiles described the data better than several other classification procedures applied to the same data. CONCLUSIONS: In nursing homes, elderly and oldest-old residents often have multiple comorbidities and disabilities. A multivariate procedure was able to identify the fundamental dimensions describing residents' variation on a number of health measures. These profiles predicted differences in service use so they had predictive validity. Thus, multivariate procedures may help identify clinically distinct groups in studies where complex measures are made.

Neuroleptic-induced catatonia as a stage in the progression toward neuroleptic malignant syndrome.

Neuroleptic-induced catatonia is reported in an adolescent patient who responded successfully to lorazepam. The authors propose five discrete stages toward the progression of neuroleptic malignant syndrome, each with a separate treatment.

Quantitative analysis of cold stress performance after digital replantation.

Isolated cold stress testing (ICST) has been used to assess cold stress performance or digital thermoregulation, but statistical analysis of the results has been limited to visual comparisons of data. In this prospective study, 11 patients who underwent complete digital replantation were followed serially with ICST at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively, and the results were analyzed quantitatively. For that analysis, we devised a mathematical method that provided a cooling and a warming coefficient to fit the data. Differences in these cooling and warming coefficients were then regressed against time after replantation, patient age, number of digits replanted, hand dominance, and clinical evidence of sensory recovery. There was a significant correlation between response to isolated cold stress testing (thermoregulation) and degree of sensory recovery (p less than or equal to 0.02). This method for quantitative analysis of isolated cold stress testing data allows objective evaluation of digital blood flow patterns based on temperature, thereby providing a reliable and objective assessment of the recovery of thermoregulation in the replanted human digit.

Use of Medicare services before and after introduction of the prospective payment system.

OBJECTIVE: The case mix-adjusted pattern of use of health care services, especially posthospital care, is compared before and after the introduction of Medicare's Prospective Payment System (PPS). DATA SOURCES: The 1982 and 1984 National Long Term Care Surveys (NLTCS) linked to Medicare administrative records 1982-1986 provide health and health service use data for 12-month periods before and after the introduction of PPS. STUDY DESIGN: Case-mix differences between pre- and post-periods are controlled by using the Grade of Membership model to identify health groups from the NLTCS data. Differences in timing (e.g., hospital length of stay) were controlled using life table models estimated for each health group, that is, service use patterns pre- and post-PPS are compared within groups. PRINCIPAL FINDINGS: Hospital LOS and admission rates declined post-PPS. Changes in the timing and location of death occurred but, overall, mortality did not increase. Changes in post-acute care service use by elderly, chronically disabled Medicare beneficiaries were observed: home health service use increased overall and among the unmarried disabled population. CONCLUSIONS: PPS did not adversely affect quality of care as reflected in mortality or in hospital readmissions. Moreover, the differential use of post-acute care, and changes in hospital LOS by health group, indicate that the system responded, specific to marital status and age, to the severity of needs of chronically disabled persons.

Home health and skilled nursing facility use: 1982-90.

In this article, analyses are made of home health and skilled nursing facility (SNF) use for the period 1982-90 using Medicare records linked to data on community and institutional residents from the National Long-Term Care Surveys (NLTCSs) of 1982, 1984, and 1989. The combined survey and administrative data analyses are performed to ascertain how the chronic health and functional characteristics of community and institutional residents using Medicare-reimbursed services changed during the period. During this period, changes had been made in the Medicare system that affected the use of services for persons with specific health and functional problems.

Functionally and medically defined subgroups of nursing home populations.

The functional and health characteristics of nursing home residents in New York State using a multivariate classification procedure are examined in this article. This analysis suggested that these characteristics could be explained in terms of six dimensions. The association of these six dimensions with two existing sets of nursing home case-mix groups was analyzed in order to determine how groups based only on the health and functional characteristics of residents related to groups based primarily on measures of current service use. A number of resident characteristics were not described well by case-mix measures based only on service use, suggesting the need to modify such groups using additional sources of input.

Sex differences in human mortality and aging at late ages: the effect of mortality selection and state dynamics.

Models of gender differences in human mortality and aging depend on assumptions about temporal rates of physiological change. Simple models like the Gompertz fail to describe the mortality of either males or females at late ages. This suggests a need for biologically more detailed models to represent the age dependency of human mortality as well as gender differences in that age dependence. By modeling the sex-specific interaction of time-varying covariates with multiple dimensions of mortality selection, one can more accurately describe the age dependence of mortality and more complex physiological aging patterns. The multivariate model of aging changes is used to describe gender differences using data from (a) a longitudinal study of physiological changes and mortality and (b) a nationally representative longitudinal survey of changes in function and mortality.

Multivariate procedures to describe clinical staging of melanoma.

Analyzing multivariate clinical data to identify subclasses of patients being treated for a specific disease may improve patient management and increase understanding of the behavior of disease under clinical conditions. In some cases, patients have been classified on prognostic characteristics using standard risk assessment procedures (e.g., Cox' regression). This requires long term follow-up, differentiates patients only on attributes relevant to survival, and assumes that patients are sampled from a common population. Other approaches involve the use of clustering algorithms to classify patients into categories based on multiple clinical attributes. We illustrate the use of a multivariate statistical procedure to directly characterize patients on multiple clinical characteristics. The procedure is designed to analyze discrete response data with parameters representing individual differences within groups. Its use is illustrated for patients with Stage I melanoma in determining how age is related to treatment response in different patient groups.

Formaldehyde exposure in nonoccupational environments.

Free formaldehyde may be released from wood products and foam insulation where urea-formaldehyde resins have been used. From January, 1978 to November, 1979, 100 structures were investigated by the Wisconsin Division of Health after receiving complaints of health problems from occupants. Air samples were collected in midget impingers and analyzed for formaldehyde content by the chromotropic acid procedure. Health information was obtained from the occupants via questionnaires. Mean formaldehyde concentration observed ranged from below the limit of detection to 3.68 ppm. Eye irritation, burning eyes, runny nose, dry or sore throat, headache, and cough were the primary symptoms which were reported by the occupants. Statistically significant associations were seen between formaldehyde levels and age of home/building materials. Observations presented suggest nonoccupational, indoor environmental exposure to formaldehyde is significant and may reach levels which exceed occupational exposure standards.

The construction of tridimensional representation of body and external reality in man. The greatest achievement of evolution to date implications for virtual reality.

Our 3-D Body Representation constructed during development by our Central Nervous System under the direction of our DNA, consists of a holographic representation arising from sensory input in the cerebellum and projected extraneurally in the brain ventricular fluid which has the chemical structure of liquid crystal. The structure of 3-D holographic Body Representation is then extrapolated by such cognitive instruments as boundarization, geometrization and gestalt organization upon the external environment which is perceived consequently as three dimensional. When the Body Representation collapses as in psychotic panic states. patients become terrified as they suddenly lose the perception of themselves and the world around them as three dimensional, solid in a reliably solid environment but feel suddenly that they are no longer a person but a disorganized blob. In our clinical practice we found serendipitously that the structure of three dimensionality can be restored even without medication by techniques involving stimulation of the body sensory system in the presence of a benevolent psychotherapist. Implications for Virtual Reality will be discussed.