Genetic epidemiologic studies on age-specified traits. NIA Aging and Genetic Epidemiology Working Group.
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This commentary calls attention to the value of combining genetic and epidemiologic methods in studies to understand the determinants of two crucial aspects of aging: ages at which certain outcomes (e.g., disease, mortality) occur and rates of change with age of individual's characteristics (e.g., physiologic functions, disease risk factors). Inclusion of age in the specification of traits in genetic epidemiologic studies could lead to improved strategies to increase healthy life expectancy and evaluate individuals' risk for age-related morbidity. Special issues that make genetic epidemiologic approaches important for studies of age-specified phenomena as well as opportunities and challenges for such studies are discussed, including study designs, sampling frames, databases, analytic tools, and related methodological issues. This commentary is based on a report prepared by the Aging and Genetic Epidemiology Working Group, convened by the National Institute on Aging to review opportunities for research on the genetic epidemiology of aging-related outcomes. The report, which contains more extensive discussion, literature review, and references, is available on the World Wide Web at http://www.nih.gov/nia/conferences/GeneticReport111199.htm. (+info)
Cellular telephones and cancer--a nationwide cohort study in Denmark.
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BACKGROUND: Use of cellular telephones is increasing exponentially and has become part of everyday life. Concerns about possible carcinogenic effects of radiofrequency signals have been raised, although they are based on limited scientific evidence. METHODS: A retrospective cohort study of cancer incidence was conducted in Denmark of all users of cellular telephones during the period from 1982 through 1995. Subscriber lists from the two Danish operating companies identified 420 095 cellular telephone users. Cancer incidence was determined by linkage with the Danish Cancer Registry. All statistical tests are two-sided. RESULTS: Overall, 3391 cancers were observed with 3825 expected, yielding a significantly decreased standardized incidence ratio (SIR) of 0.89 (95% confidence interval [CI] = 0.86 to 0.92). A substantial proportion of this decreased risk was attributed to deficits of lung cancer and other smoking-related cancers. No excesses were observed for cancers of the brain or nervous system (SIR = 0.95; 95% CI = 0.81 to 1.12) or of the salivary gland (SIR = 0.72; 95% CI = 0.29 to 1.49) or for leukemia (SIR = 0.97; 95% CI = 0.78-1.21), cancers of a priori interest. Risk for these cancers also did not vary by duration of cellular telephone use, time since first subscription, age at first subscription, or type of cellular telephone (analogue or digital). Analysis of brain and nervous system tumors showed no statistically significant SIRs for any subtype or anatomic location. CONCLUSIONS: The results of this investigation, the first nationwide cancer incidence study of cellular phone users, do not support the hypothesis of an association between use of these telephones and tumors of the brain or salivary gland, leukemia, or other cancers. (+info)
Secular trends in the epidemiology and outcome of Barrett's oesophagus in Olmsted County, Minnesota.
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BACKGROUND: The incidence of oesophageal adenocarcinoma has increased greatly. Barrett's oesophagus is a known risk factor. AIMS: To identify changes in the incidence, prevalence, and outcome of Barrett's oesophagus in a defined population. SUBJECTS: Residents of Olmsted County, Minnesota, with clinically diagnosed Barrett's oesophagus, or oesophageal or oesophagogastric junction adenocarcinoma. METHODS: Cases were identified using the Rochester Epidemiology Project medical records linkage system. Records were reviewed with follow up to 1 January 1998. RESULTS: The incidence of clinically diagnosed Barrett's oesophagus (>3 cm) increased 28-fold from 0.37/100 000 person years in 1965-69 to 10.5/100 000 in 1995-97. Of note, gastroscopic examinations increased 22-fold in this same time period. The prevalence of diagnosed Barrett's oesophagus increased from 22.6 (95% confidence interval (CI) 11.7-33.6) per 100 000 in 1987 to 82.6/100 000 in 1998. The prevalence of short segment Barrett's oesophagus (<3 cm) in 1998 was 33.4/ 100 000. Patients with Barrett's oesophagus had shorter than expected survival but only one patient with Barrett's oesophagus died from adenocarcinoma. Only four of 64 adenocarcinomas occurred in patients with previously known Barrett's oesophagus. CONCLUSIONS: The incidence and prevalence of clinically diagnosed Barrett's oesophagus have increased in parallel with the increased use of endoscopy. We infer that the true population prevalence of Barrett's oesophagus has not changed greatly, although the incidence of oesophageal adenocarcinoma increased 10-fold. Many adenocarcinomas occurred in patients without a previous diagnosis of Barrett's oesophagus, suggesting that many people with this condition remain undiagnosed in the community. (+info)
Maternal mortality in New York City: excess mortality of black women.
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To assess maternal mortality in New York City, birth certificates and mortality records for New York City from 1988 through 1994 were linked and examined. During these 7 years, maternal mortality in New York City (defined by the International Classification of Diseases, 9th edition [ICD-9], as 630-676) per 100,000 live births significantly exceeded that of the country as a whole (20.2 vs. 8.2, respectively). Within New York City, an even greater variation of maternal mortality by race/ethnicity was noted, with the mortality ratio of whites, blacks, and Hispanics being 7.1, 39.5, and 14.4 per 100,000 live births, respectively. Socioeconomic characteristics such as educational attainment, marital status, and income influenced maternal mortality more in non-blacks than blacks. Analyses of cause-specific mortality revealed that, overall, ectopic pregnancy, embolism, and hypertension were the leading causes of death. However, the major factors explaining the excess maternal mortality among blacks were hypertension (mortality ratio of blacks to whites 5.57, 95% confidence interval 2.30-13.39), ectopic pregnancy (4.78, 95% confidence interval 2.40-9.51), and abortion (4.58, 95% confidence interval 1.72-12.22). These findings confirm a persisting gap in maternal death between black and white women. Indeed, if all New Yorkers who became pregnant enjoyed the survival of the city's non-Hispanic white residents, the difference in maternal mortality between the city and the nation would be eliminated. (+info)
Undiagnosed diabetes: does it matter?
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BACKGROUND: The 1998 Canadian clinical practice guidelines for the management of diabetes lowered the cutoff point for diagnosing diabetes mellitus from a fasting plasma glucose (FPG) level of 7.8 to 7.0 mmol/L. We studied the prevalence and clinical outcomes of undiagnosed and diagnosed diabetes within specific ranges of FPG among a cohort of subjects recruited in 1990. METHODS: In 1990 a representative sample of 2792 adult residents of Manitoba participated in the Manitoba Heart Health Survey, which included measurement of FPG and a question about each participant's past history of diabetes. Individuals who would now be classified as having undiagnosed diabetes under the new criteria were not considered as such in 1990. Through data linkage with the provincial health care utilization database, the use of health care by these individuals was tracked and compared with that of individuals whose diabetes had been diagnosed and with that of normoglycemic individuals over an 8-year period subsequent to the survey. RESULTS: The prevalence of undiagnosed diabetes in the adult population of Manitoba was 2.2%. Undiagnosed cases accounted for about one-third of all diabetes cases. Individuals with undiagnosed diabetes had an unfavourable lipid profile and higher blood pressure and obesity indices than normoglycemic individuals. Individuals who satisfied the new criteria for diabetes but remained undiagnosed had an additional 1.35 physician visits per year (95% confidence interval [95% CI] 0.93-1.96) and were more likely to be admitted to hospital at least once (odds ratio 1.23, 95% CI 0.40-3.79), compared with normoglycemic individuals. INTERPRETATION: Undiagnosed cases represent the unseen but clinically important burden of diabetes, with significant concurrent metabolic derangements and a long-term impact on health care use. (+info)
Idiopathic thrombocytopenic purpura and MMR vaccine.
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A CAUSAL ASSOCIATION BETWEEN MEASLES: mumps-rubella (MMR) vaccine and idiopathic thrombocytopenic purpura (ITP) was confirmed using immunisation/hospital admission record linkage. The absolute risk within six weeks of immunisation was 1 in 22 300 doses, with two of every three cases occurring in the six week post-immunisation period being caused by MMR. Children with ITP before MMR had no vaccine associated recurrences. (+info)
A method for identifying underlying causes of death in epidemiological study.
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To obtain the underlying causes of death in individuals of a cohort (male only), the items of date of birth, date of death and address code at the time of death were linked between the data of resident cards and the death tapes of National Vital Statistics supplied by the Ministry of Health and Welfare. As a result, the persons who have the same information for above mentioned three items between the resident cards and the death tapes accounted for 97.4%. If the persons who had the same information for three items except one item were considered to be identical, they accounted for 99.4%. It would be concluded that underlying cause of death can be obtained by record linkage of death tapes of National Vital Statistics with three informations in residence cards, dates of birth, dates of death and address codes at the time of death, even without names of the individual in the death tapes. The matched rate would be high enough for epidemiological studies. (+info)
Record linkage of health care insurance claims.
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OBJECTIVE: This paper provides a detailed description of a method developed for purposes of linking records of individual patients, represented in diverse data sets, across time and geography. DESIGN: The procedure for record linkage has three major components-data standardization, weight estimation, and matching. The proposed method was designed to incorporate a combination of exact and probabilistic matching techniques. MEASUREMENTS: The procedure was validated using convergent, divergent, and criterion validity measures. RESULTS: The output of the process achieved a sensitivity of 92 percent and a specificity that approached 100 percent. CONCLUSIONS: The procedure is a first step in addressing the current trend toward larger and more complex databases. (+info)