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Biomedical subjects

J L Lyon

Publications and source records attributed to J L Lyon.

At least 19 recordsLinked to original sources
PubMed1992

Hip fractures and fluoridation in Utah's elderly population.

OBJECTIVE: To test the effect of water fluoridated to 1 ppm on the incidence of hip fractures in the elderly. DESIGN: Ecological cohort. SETTING: The incidence of femoral neck fractures in patients 65 years of age or older was compared in three communities in Utah, one with and two without water fluoridated to 1 ppm. PATIENTS: All patients with hip fractures who were 65 years of age and older over a 7-year period in the three communities, excluding (1) those with revisions of hip fractures, (2) those in whom the hip fracture was anything but a first diagnosis, (3) those in whom metastatic disease was present, or (4) those in whom the fracture was a second fracture (n = 246). OUTCOME MEASURE: Rate of hospital discharge for hip fracture. RESULTS: The relative risk for hip fracture for women in the fluoridated area was 1.27 (95% confidence interval [CI] = 1.08 to 1.46) and for men was 1.41 (95% CI = 1.00 to 1.81) relative to the nonfluoridated areas. CONCLUSIONS: We found a small but significant increase in the risk of hip fracture in both men and women exposed to artificial fluoridation at 1 ppm, suggesting that low levels of fluoride may increase the risk of hip fracture in the elderly.

Aged↗
PubMed1992

Coffee consumption and the risk of cancer of the exocrine pancreas: a case-control study in a low-risk population.

Data from a population-based, case-control study of 149 cases of cancer of the exocrine pancreas (excluding insulinomas) and 363 controls were used to test the hypothesis that coffee consumption increased the risk of cancer of the exocrine pancreas. Because of the high mortality from cancer of the pancreas, all information was obtained from proxy respondents for cases and controls. Increased risk was present for coffee drinkers [odds ratio (OR) = 2.38], cigarette smokers (OR = 2.27), and alcohol users (OR = 1.60), but the effect for alcohol disappeared after adjustment for cigarette use. Risk increased with the amount of coffee drunk with an OR of 2.38 in the those having at least 50,000 lifetime cups. This gradient was present in both men and women, and in cigarette smokers and nonsmokers. Increased risk was present for users of regular and decaffeinated coffee, but the risk was higher for users of decaffeinated coffee than users of regular coffee. Cigarette smoking, after controlling for coffee consumption, was an independent risk factor for pancreatic cancer, with odds ratios in the heaviest smokers of 2.71 (95% confidence interval = 1.41-5.21.

Adult↗
PubMed1992

Misclassification of exposure in a case-control study: the effects of different types of exposure and different proxy respondents in a study of pancreatic cancer.

This investigation addressed three questions about misclassification in a case-control study of risk factors for pancreatic cancer in which all exposure data were obtained from proxy respondents. These questions were: (1) To what degree was misclassification dependent on the type of exposure? (2) To what degree did misclassification vary by the type of proxy? (3) What was the magnitude of the effect of proxy misclassification on odds ratios measured across several levels of exposure? To answer these questions, we interviewed 163 control (index) subjects and next-of-kin (proxy) respondent pairs. Each of the controls and their respective proxies reported the control's use of coffee, cigarettes, and alcohol and weekly exposure to beef, milk, bacon, fruits, and vegetables. Nonspouse proxies misclassified exposures more than spouse proxies with the exception of cigarettes. Cigarette use was the most accurately reported exposure, followed by alcohol, coffee, and foods. For nondifferential misclassification between cases and controls, the slope of a dose-response curve was decreased from 6.6% to 100% depending on the exposure and the type of proxy respondent. Investigators conducting studies using proxy respondents need to recognize that misclassification is a function of multiple factors, including both the type of exposures under study and the type of proxies available.

Adult↗
PubMed1991

Antigenic stimulation and the occurrence of chronic lymphocytic leukemia.

Data from a population-based case-control study of chronic lymphocytic leukemia were analyzed to assess the possible etiologic role of chronic antigenic stimulation. The study, conducted in four geographic areas of the United States (the metropolitan areas surrounding Seattle, Washington, Salt Lake City, Utah, Detroit, Michigan, and Atlanta, Georgia) sought to identify all incident cases (n = 430) among residents diagnosed between July 1, 1977 and December 31, 1981. The responses of these cases to questions about possible sources of antigenic stimulation were compared with the responses of controls selected from the populations of these areas. Little difference between cases and controls was present for a history of most forms of viral and bacterial infection and for a history of allergies or allergy treatment. However, a relation was observed with antecedent syphilis infection (odds ratio (OR) = 5.0, 95% confidence interval (Cl) 2.0-12.9). Associations of smaller magnitude were observed with a history of tuberculosis (OR = 1.9, 95% Cl 1.0-3.7) and of urinary tract infection (OR = 1.4, 95% Cl 1.1-1.9). Overall, however, the authors found little evidence of a relation between chronic antigenic stimulation and the occurrence of chronic lymphocytic leukemia. Nonetheless, because the measure of prior antigenic stimulation was restricted to that obtained through interviews and undoubtedly was an insensitive one, these negative results should not be interpreted as ruling out antigenic stimulation as a possible cause of some cases of chronic lymphocytic leukemia.

Aged↗
PubMed1991

Cigarette smoking: risk factor for premature facial wrinkling.

OBJECTIVE: To determine if cigarette smoking is a risk factor for the development of premature facial wrinkling. DESIGN: Cross-sectional study. SETTING: Smoking cessation clinic and community. PATIENTS: Convenience sample of 132 adult smokers and non-smokers in 1988. MEASUREMENTS: A questionnaire was administered to quantify cigarette smoking and to obtain information about possibly confounding factors such as skin pigmentation, sun exposure, age, and sex. Wrinkling was assessed using photographs of the temple region, and a severity score based on predetermined criteria was assigned. A logistic regression model, which controlled for confounding variables, was developed to assess the risk for premature wrinkling in response to pack-years of smoking. MAIN RESULTS: The prevalence of premature wrinkling was independently associated with sun exposure and pack-years of smoking. After controlling for age, sex, and sun exposure, premature wrinkling increased with increased pack-years of smoking. Heavy cigarette smokers (greater than 50 pack-years) were 4.7 times more likely to be wrinkled than nonsmokers (95% CI, 1.0 to 22.6; P value for trend = 0.05). Sun exposure of more than 50,000 lifetime hours also increased the risk of being excessively wrinkled 3.1-fold (CI, 1.2 to 7.1). When excessive sun exposure and cigarette smoking occurred together, the risk for developing excessive wrinkling was multiplicative (prevalence ratio of 12.0; CI, 1.5 to 530). CONCLUSION: Cigarette smoking is an independent risk factor for the development of premature wrinkling.

Adult↗
PubMed1991

Natural history of thyroid abnormalities: prevalence, incidence, and regression of thyroid diseases in adolescents and young adults.

PURPOSE: This study reports the prevalence, incidence, and regression of thyroid abnormalities in a population observed from adolescence to adulthood. PATIENTS AND METHODS: Examinations for thyroid abnormalities were performed in 4,819 school-age children, ages 11 to 18, in 1965 to 1968; two thirds of this original cohort (3,121) were re-examined 20 years later (1985 to 1986). Each subject with a thyroid abnormality detected by physical examination was studied by means of a series of re-examinations, and tests of thyroid function, imaging, and biopsy to determine the exact nature of the thyroid abnormality. RESULTS: In the initial examinations (1965 to 1968), 185 thyroid abnormalities were found (3.7%). Diffuse hypertrophy with normal function (adolescent goiter) was the most common abnormality (19.3/1,000); 12.7/1,000 had chronic lymphocytic thyroiditis, and 4.6/1,000 had thyroid nodules, including two papillary carcinomas. Hyperthyroidism or hypothyroidism was found in 1.9/1,000. In the follow-up examinations in 1985 to 1986, 298 subjects had thyroid abnormalities (10.5%), of whom 81 (28.7/1,000) had simple goiters, 145 (51.3/1,000) had chronic thyroiditis, 45 (15.9/1,000) had hypothyroidism, 11 (3.9/1,000) had hyperthyroidism, and 66 (23.2/1,000) had nodules, which included 10 carcinomas. Of the 92 subjects with simple or adolescent goiter in 1965 to 1968, 60% were normal by 1985 to 1986, 20% were unchanged, and a few had developed thyroiditis (10%) or colloid goiters (3.0%). Of 61 subjects with thyroiditis, 27% had become normal, 33% remained unchanged, and 33% had become hypothyroid. Of the 22 subjects with thyroid nodules, two had complete disappearance of the nodules, and three had nodules considered to be variants of normal. The others exhibited a variety of nodular pathologic conditions. CONCLUSIONS: The natural history of thyroid disorders, including simple goiter, chronic thyroiditis, hyperthyroidism, hypothyroidism, and nodular diseases of the thyroid, indicates they are dynamic and changeable in form, function, appearance, and disappearance.

Adolescent↗
PubMed1990

Leukemia in Utah and radioactive fallout from the Nevada test site. A case-control study.

Previous studies reported an association between leukemia rates and amounts of fallout in southwestern Utah from nuclear tests (1952 to 1958), but individual radiation exposures were unavailable. Therefore, a case-control study with 1177 individuals who died of leukemia and 5330 other deaths (controls) was conducted using estimates of dose to bone marrow computed from fallout deposition rates and subjects' residence locations. A weak association between bone marrow dose and all types of leukemia, all ages, and all time periods after exposure was found. This overall trend was not statistically significant, but significant trends in excess risk were found in subgroups defined by cell type, age, and time after exposure. The greatest excess risk was found in those individuals in the high-dose group with acute leukemia who were younger than 20 years at exposure and who died before 1964. These results are consistent with previous studies and with risk estimates for other populations exposed to radiation.

Acute Disease↗
PubMed1990

Childhood brain tumor: presentation at younger age is associated with a family tumor history.

In a registry-based sample of 361 children with a brain tumor, those whose grandparents and great-grandparents had a history of any kind of tumor were younger at the time of presentation than were those who lacked this family history (p = 0.1). In post hoc analyses, the age difference was most apparent among children with cerebral tumors, and when family history was limited to brain tumors and to great-grandparents. These findings are in keeping with the hypothesis that a familial tumor diathesis contributes to an early age at onset of a brain tumor in some children.

Age Factors↗
PubMed1990

Cohort study of thyroid disease near the Nevada Test Site: a preliminary report.

The atmospheric testing of nuclear weapons in Nevada beginning in 1951 resulted in exposure of regions surrounding the Nevada Test Site (NTS) to fallout. A cohort of children born between 1947 and 1954 in two counties near the NTS, one in Utah and one in Nevada (UT/NV), were examined in 1965-1968 for thyroid abnormalities that might have been a result of exposure to radioiodine in fallout. The prevalence of thyroid abnormalities in these children (11-18 y) was compared to that in a control group selected from a county in Arizona (AZ) that was presumed to have received little or no fallout from the NTS. Thyroid nodules were found in 76 of the 4,819 children examined (15.8/1000). Of the 76 thyroid nodules, 22 were diagnosed as neoplasms. The rate of thyroid neoplasms among the UT/NV subjects was higher (5.6/1000) than among the AZ subjects (3.3/1000) (RR = 1.7), but because the number of neoplasms was small, the difference was statistically insignificant. In 1985-1986, 3,122 of the original study subjects were reexamined. In this reexamination, thyroid nodules were found in 125 individuals (44.2/1000). Of the 125 thyroid nodules detected during this later study period, 65 were considered to be thyroid neoplasms. Rates of thyroid neoplasms in UT/NV (24.6/1000) are again slightly higher than in AZ (20.2/1000) (RR = 1.2), but the difference is not significant (p = 0.65). Based on the rates of thyroid neoplasms in the two geographic locations, we conclude that living near the NTS in the 1950s has not resulted in a statistically significant increase of thyroid neoplasms in subjects from UT/NV when compared with subjects of the same age and gender living in AZ.

Adolescent↗
PubMed1979

Childhood leukemias associated with fallout from nuclear testing.

Continuing concern over the possible carcinogenic effects of low-level radiation prompted us to study the population of Utah because of its exposure to fallout from 26 nuclear tests between 1951 and 1958. Certain rural counties (high-fallout counties) received most of the fallout during that period. We reviewed all deaths from childhood (under 15 years of age) cancers occurring in the entire state between 1944 and 1975 and assigned them to a cohort of either high or low exposure, depending on whether 15 between 1951 and 1958. For reasons unknown, leukemia mortality among the low-exposure cohort in the high-fallout counties was about half that of the United States and the remainder of the state. Mortality increased by 2.44 times (95 per cent confidence, 1.18 to 5.02) to just slightly above that of the United States in the high-exposure cohort residing in the high-fallout counties, and was greatest in 10- to 14-year-old children. For other childhood cancers, no consistent pattern was found in relation to fallout exposure. The increase in leukemia deaths could be due to fallout or to some other unexplained factor.

Adolescent↗
PubMed1978

Gastric cancer in a coal mining region.

A significant excess incidence of gastric cancer was previously reported in the coal mining counties of Utah for 1965-1969. A repeat study for the period 1970-1975 showed the rates to be close to expectation and are in line with the slight excess mortality reported by Creagan et al. from United States coal mining counties. A cluster of 12 cases out of 43 reported for the 11-year period occurred in 1965. Cases during 1966-1975 appear to have occurred at random by year. The previous suggestion that the high incidence of gastric cancer in Carbon and Emery Counties could be related to frequent exposure to coal-carrying hydrocarbons appears to be unwarranted.

Adolescent↗
PubMed1978

Colon cancer in a low-risk population.

Data are presented on colon mortality in Utah. For the years 1950 to 1969, the state population had 34% fewer deaths from colon cancer than the average United States population. Colon cancer incidence was also studied for the years 1966 to 1970, both for the state and for a large subgroup (Mormons) who abstain from tobacco and alcohol for religious reasons; the colon cancer incidence of Mormons was 37% below the United States average, and that of non-Mormons was 18% below the United States average. A preliminary dietary survey found little difference in meat, fat, and fiber consumption between the population of Utah and that of the United States as a whole.

Christianity↗
PubMed1978

Cardiovascular mortality in Mormons and non-Mormons in Utah, 1969--1971.

Cardiovascular mortality in the State of Utah is among the lowest in the United States. The religion of 72% of the state residents (Mormon) proscribes the use of tobacco and alcohol; a large number of Mormons adhere to this proscription. This study analyzed the 6108 cardiovascular disease deaths between 1969--1971 in Utah of members in the Mormon Church. For both sexes, Mormons had 35% less mortality than expected from US rates for ischemic heart disease, while non-Mormons were not significantly different from US whites. These results support the relationship between cigarette smoking and mortality from cardiovascular disease. Mormon men also had lower mortality from hypertensive heart disease and Mormon women from rheumatic heart disease than non-Mormons in Utah.

Aged↗