Chief, Biometry Section (Vacant)
Laboratory of Epidemiology, Demography, and Biometry |
| Survival Analysis and Modeling: Recent work in longitudinal data analysis involves development and application of Cox proportional hazards models to study risk factors for onset of Alzheimer's disease (AD) and other dementias in the Honolulu-Asia Aging Study of dementia. Rarely is the date of onset for AD or other forms of dementia in epidemiological studies well established and available for the study of incidence and relative risks. Using the recommendations of several published papers we developed a standardized approach for establishing a date of onset for incident cases of dementia in the Honolulu-Asia Aging Study (HAAS) to investigate risk factors with Cox proportional hazards models. In this model, a date of onset is assumed to be the midpoint between two HAAS examinations in which a participant is free of dementia in the earlier examination and then receives a diagnosis in the subsequent examination. Participants without a subsequent examination due to death or to refusal are excluded from the analyses because the course of their cognitive status is unknown. Use of this Cox proportional hazard model has facilitated analyses of data from the midlife examinations which were gathered between 1965 and1975 on the HAAS cohort members as part of their prior recruitment into the Honolulu Heart Program to study cardiovascular disease beginning in 1965 among 8,006 Japanese-American men born 1900 to 1919 |
| Prevalence and Consequences of Sleep-Disordered Breathing and Other Sleep Disorders: For more than a decade, the epidemiological importance of obstructive sleep apnea and other forms of sleep-disordered breathing have gained attention as risk factors for cardiovascular disease and other adverse clinical endpoints including neuropsychological deficits. The estimation of the prevalence of sleep-disordered breathing, and in particular obstructive sleep apnea based on epidemiological studies, has been limited by small sample sizes due to the cost of overnight polysomnography in a sleep laboratory for diagnosis. Consequently, a major initiative to develop portable polysomnography for unattended overnight sleep recordings in a person's home facilitated the launch of the large multi-centered Sleep Heart Health Study (SHHS) to assess cardiovascular consequences of sleep-disordered breathing among adults aged 40 years and older. The SHHS also provided support for use of the portable polysomnography in the HAAS. Between 1999 and 2000, a total of 718 of the 1,524 surviving HAAS cohort members aged 79 to 97 years completed an overnight polysomnography using the SHHS protocol. This landmark study provides an opportunity to investigate the association between obstructive sleep apnea and cognitive impairment in a population of elderly men who are at high risk of developing dementia. |
| Self-reported data on sleep problems in several LEDB funded studies including the HAAS and the EPESE have provided epidemiological data on the prevalence, correlates and consequences of symptoms of insomnia and for symptoms of excessive daytime sleepiness among older adults. The earlier descriptive findings led to more recent initiatives to describe the epidemiology of chronic insomnia in the elderly as secondary to the onset and progression of chronic diseases including heart disease, stroke, arthritis and diabetes to name a few. Importantly, these findings highlight the need for advances in both cognitive-behavioral therapy and in long-term use of sleeping pills such as zolpidem and zaleplon. |
| Epidemiology of Death and Dying: Each year, nearly 2 million men and women age 65 years and older die from a variety of causes. Data from the National Mortality Followback Surveys and the Established Populations for Epidemiologic Studies of the Elderly (EPESE) provide opportunities to improve knowledge about mortality trends, particularly for Alzheimer's disease related deaths, and about dying trajectories. Currently, AD is among the 10 leading causes of death among the population age 65 years and older. In collaboration with lead investigators from the LEDB, Epidemiology and Demography Section, several distinct patterns of dying trajectories have been developed and examined using data from the EPESE. |
| Aging and Driver Safety: Older drivers have the second highest driver fatality rate in the nation while teen drivers have the greatest risk. Aging often corresponds with marked decrements in visual, cognitive and physical functioning that can compromise driving skills. Each year, over 600,000 elderly adults stop driving because of their health. The effects of vision impairments and dementia on driving skill are supported by numerous epidemiological studies in contrast to epidemiological studies of physical impairments and driver safety. Importantly, the HAAS provides both upper and lower extremity performance measures for investigating the relationships among impairments, unsafe driving, and driving cessation. Because unsafe driving is based on self-reported crash histories, an initiative to acquire data from license and crash records maintained by the Hawaii Department of Transportation is planned for future analyses. |
