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Biomedical subjects

H Austin

Publications and source records attributed to H Austin.

At least 37 records · Page 2Linked to original sources
PubMed1996

Simple anthropometric indices associated with ischemic heart disease.

In a case-control study of 217 hospitalized incident cases of ischemic heart disease and 261 controls we compared various anthropometric indices for the strength of their associations to the outcome event. The ratio of supine sagittal abdominal diameter to midthigh girth ("abdominal diameter index"; ADI) was the simple index that best discriminated cases from controls for both men (standardized difference, 0.65; p < 0.0001) and women (standardized difference, 0.95; p < 0.0001). The waist-to-thigh ratio of girths (WTR) (standardized difference, 0.57 and 0.90; p < 0.0001) was nearly as strong as the ADI and stronger than the traditional waist-to-hip ratio (standardized difference, 0.34 and 0.68; p < 0.005). After adjustments for age and race, the men's odds ratio for ischemic heart disease (tertile 3 vs. tertile 1) was 5.5 (95% CI, 2.9-10) using ADI and 5.1 (2.6-10) using the WTR. The women's odds ratio was 6.3 (1.9-20) using ADI and 8.7 (2.3-33) using the WTR. Further adjustments for body mass index and cardiovascular risk factors did not substantially change these risk estimates. Similar odds ratios were estimated by analyses restricted to 169 neighborhood-matched case-control pairs. In contrast, increased midthigh girth and subcutaneous fat mass (sum of three skinfolds) were associated with a protective effect against ischemic heart disease. Anthropometry using the ADI or WTR could offer a low-cost, noninvasive method for the clinical or epidemiologic evaluation of ischemic heart disease risk.

Anthropometry↗
PubMed1996

Exact estimates for a rate ratio.

The incidence rate ratio is a basic measure of association in epidemiology. We present a simple and efficient method for computing exact confidence limits for the common rate ratio in a series of 2 x 2 tables with person-time denominators. The method uses a polynomial multiplication (convolution) algorithm previously described for an odds ratio. We also present two tests, one asymptotic, the other exact, for evaluating rate ratio homogeneity. We extend these homogeneity tests to apply to data where strata have been partitioned into subgroups in which the rate ratio is assumed homogeneous within subgroups, but not necessarily between them. We conclude with a brief description of a microcomputer program that computes exact and asymptotic estimates for both a rate ratio and an odds ratio.

Algorithms↗
PubMed1995

Racial differences in tumor grade among women with endometrial cancer.

Black women with endometrial cancer have more advanced disease and less favorable tumor grade than do white women. This study evaluated whether racial differences in tumor grade could be explained by hormone-related factors and other putative determinants of grade. Subjects included 207 white and 81 black postmenopausal women diagnosed with primary cancer of the uterine corpus between 1985 and 1987. Blacks had poorer tumor grade than whites (odds ratio for FIGO grade 2 versus grade 1 is 1.8; odds ratio for grade 3 versus grade 1 is 2.8). Over 75% of the excess of poorly differentiated tumors versus well-differentiated tumors among blacks could be explained by racial differences in use of replacement estrogens, age at first pregnancy, history of oophorectomy, poverty, stage of disease, use of screening, and access to health care. The most prominent factor was estrogen therapy, which was associated with favorable tumor grade and was used much less frequently by blacks. Although not statistically significant, a moderate racial difference in tumor grade remained after control of the potential explanatory explanatory variables. This may reflect true biologic variation between blacks and whites and may explain, in part, the observation that blacks with endometrial cancer have a worse prognosis.

Black or African American↗
PubMed1994

Demographic and geographic variability of kidney stones in the United States.

To characterize demographic and regional variation in kidney stone prevalence in the U.S. we studied two nationwide cross-sectional surveys that included data on self-reported, physician-diagnosed kidney stones, supplementing published data on hospitalizations for stones. The larger study, Cancer Prevention Study II (CPS II), included 1,185,124 men and women, age > or = 30, recruited nationally in 1982, and provides state-specific prevalence estimates. The National Health and Nutrition Examination Survey (NHANES II) was a national probability sample of 25,286 U.S. adults interviewed between 1976 and 1980. Kidney stone prevalence increased with age until age 70, then declined and was higher in men than women and in whites than blacks. Prevalence among Hispanic and Asian men was intermediate between that of whites and blacks. There was a strong, statistically significant regional variability in stone prevalence among U.S. whites. The age-adjusted prevalence increased from north to south, and from west to east. The contrast in state-specific prevalence was greatest between men in North Carolina (prevalence = 14.9; 95% confidence interval = 14.2 to 15.7) and North Dakota (5.6; 4.7 to 6.4), and between women in South Carolina (6.4; 5.8 to 6.9) and South Dakota (2.4; 1.9 to 2.9). The marked variations in kidney stone prevalence by age, gender, race, and geographic location may provide clues to their etiology and prevention.

Adult↗
PubMed1993

Diet and endometrial cancer: a case-control study.

A case-control study of 168 cases with endometrial cancer and 334 controls was conducted in Birmingham, Alabama, between June 1985 and December 1988. Cases were identified at the University of Alabama Hospital and in a private practice; controls were selected from among women who attended the University optometry clinic. A food frequency questionnaire that evaluated the intake of 55 nutrients and 116 foods was obtained for 103 cases and 236 controls. Logistic regression was used to evaluate the effect of diet on endometrial cancer after adjustment for total calories, age, race, education, obesity, smoking status, age at menarche, number of pregnancies, age at menopause, diabetes, hypertension, and use of exogenous estrogens. High intake of certain micronutrients was associated with a decreased risk of endometrial cancer: the odds ratio for subjects in the upper tertile versus those in the lower tertile was 0.4 for both carotene and nitrate (95% confidence interval (CI) 0.2-0.8 and 0.2-0.9, respectively). There also was an inverse association between endometrial cancer and protein consumption (trend test; p = 0.002), and a moderate direct association with cholesterol intake (OR = 1.9, 95% CI 0.9-3.7) when terms for both these macronutrients were included in a logistic model. Total intake of animal and vegetable fat were not associated with endometrial cancer. More frequent consumption of several vegetables and certain dairy products was associated with a statistically significant decreased risk of endometrial cancer. These results suggest that diet plays an important role in the etiology of endometrial cancer.

Carotenoids↗
PubMed1993

Mortality patterns among men in the motor vehicle manufacturing industry.

This retrospective follow-up study evaluates the mortality experience of 123,232 male hourly workers employed at a motor vehicle manufacturing company in 1973. Company computerized personnel records were used to identify subjects and to obtain their employment history. Follow-up through December 31, 1985 was conducted using company, state, and national data sources. The mortality rates of the cohort were compared with the rates of the United States (U.S.) general population of white or black men, adjusting for age and calendar time, and using the standardized mortality ratio (SMR) as the measure of association. The overall mortality rate of cohort members is lower than the U.S. rate by 11% among whites (11,060 observed/12,427 expected deaths; SMR = 89) and by 24% among blacks (3,744/4,926 deaths; SMR = 76). These low mortality rates reflect deficits of diseases other than cancer. Cancer SMRs are 99 for whites and 90 for blacks. There are slight excesses of stomach cancer (SMR = 113) and of lung cancer (SMR = 108) among whites and of cancer of the large intestine and rectum (SMR = 114) and of the lymphopoietic tissue (SMR = 111) among blacks. Both whites and blacks have a large deficit of buccal cancer and pharynx cancer, and blacks also have a deficit of esophagus cancer. The cohort's overall deficit of deaths is due largely to the favorable mortality experience of active workers. In contrast, white subjects who have left active employment have an 11% mortality excess, and inactive black subjects have a mortality rate that is similar to the general population rate. The increased mortality among inactive whites is not limited to any one particular disease category. This pattern may reflect illness-related employment termination and generalized confounding by socioeconomic status, although the study does not rule out a relationship between workplace exposures and specific diseases.

Adult↗
PubMed1993

Retrospective follow-up study of foundry and engine plant workers.

A retrospective follow-up study of 21,013 workers employed at a foundry and two engine manufacturing plants was conducted to determine if these workers had an unusual mortality experience. A total of 2,235 deaths occurred during the follow-up period of 1970-1987. Mortality from all causes was lower than expected. Men experienced a 6-13% excess of lung cancer deaths, depending on the choice of the comparison group. The data displayed evidence of a positive trend between lung cancer mortality and increasing duration of employment (p = 0.008). White men experienced a statistically significant excess of deaths from stomach cancer (standardized mortality ratio [SMR] = 158; 95% confidence interval [CI] = 101-234). Black men had increased mortality from pancreatic cancer, especially among engine plant workers (SMR = 303; CI = 121-624), and an excess of prostate cancer, concentrated among foundry workers (SMR = 234; CI = 112-430).

Adult↗
PubMed1993

A case-control study of endometrial cancer in relation to cigarette smoking, serum estrogen levels, and alcohol use.

OBJECTIVES: The purpose of this study was to evaluate the effect of cigarette smoking and alcohol use on the risk of endometrial cancer. The impact of smoking on serum estrone, estradiol, and androstenedione levels also was examined. STUDY DESIGN: This hospital-based case-control study included 168 women with endometrial carcinoma and 334 control women. RESULTS: Women who were current smokers had a lower risk of endometrial cancer than did women who did not smoke (relative rate 0.69; 95% confidence interval 0.40-1.19), whereas women who were exsmokers and women who had never smoked had similar rates (relative rate 0.83; 95% confidence interval 0.46-1.48). There was little overall association between serum estrogen levels and cigarette smoking, although estradiol levels in overweight control subjects were lower among women who were current smokers than among women who had never smoked. Androstenedione levels were slightly higher among women in the control group who smoked than among women in the control group who did not smoke, but the difference was not statistically significant (p = 0.28, two-tailed). Alcohol use was unrelated to endometrial cancer in this study. CONCLUSIONS: The study provides additional support for the hypothesis that smoking is inversely related to endometrial cancer. The inverse smoking association with endometrial cancer may be more directly related to higher serum androstenedione levels than to lower serum estrogen levels except, perhaps, among overweight women.

Adult↗
PubMed1993

Confounding by time since hire in internal comparisons of cumulative exposure in occupational cohort studies.

We use a simple, empirical model to describe the healthy worker effect mortality pattern. Under this simple model, internal comparisons of risk with increasing cumulative exposure will tend to be biased away from the null because of the healthy worker effect. We illustrate the potential magnitude of the bias in a simple situation and show that controlling for time since hire, by means of standard epidemiologic methods, eliminates the bias. Time since hire also is a concern of occupational epidemiologists because of the issue of induction time; sufficient time may not have elapsed among recently hired workers for an exposure to manifest its effect on disease occurrence. Provision for an adequate induction period can be addressed, like the concern raised in this paper, by restricting the analysis to workers first employed many years before the start of the follow-up period.

Bias↗
PubMed1992

Cigarette smoking and the incidence of cervical intraepithelial neoplasia, grade III, and cancer of the cervix uteri.

The relation between cigarette smoking and cervical intraepithelial neoplasia, grade III (CIN III), and cervical cancer was examined among a cohort of 6,812 women in Tromsö, Norway, between 1980 and 1989. During the 52,844 person-years of observation, 185 incident cases (177 women with CIN III and eight with cervical cancer) were recorded in the regional pathology registry. The age-adjusted incidence rates of CIN III and cervical cancer were 267/100,000 person-years among women who had never smoked, 183/100,000 person-years among exsmokers, and 476/100,000 person-years among current smokers. A multivariate model containing terms for age, marital status, and frequency of intoxication yielded a relative rate for current smokers compared with nonsmokers of 1.5 (95% confidence interval 1.0-2.2). Statistical trend tests for the number of cigarettes smoked per day (never, 1-14, and greater than or equal to 15 cigarettes), years of smoking (never, 1-9, and greater than or equal to 10 years), and age started smoking (less than 16, 16-18, 19-21, and greater than or equal to 22 years) all yielded significant results. These findings support the opinion that CIN III and cervical cancer are a smoking-related disease.

Adult↗
PubMed1992

A follow-up study of agricultural chemical production workers.

This retrospective follow-up study evaluated the mortality experience of 4,323 men employed at a plant in Alabama (AL) that manufactures agricultural and other chemicals. On average, there were 18 years of follow-up per subject during the study period of 1951 to 1987. The observed numbers of deaths among cohort members were compared with the numbers expected on the basis of United States (US) and AL general population mortality rates. The all causes standardized mortality ratio (SMR), computed using US rates as the referent, was 97 (233 observed/240 expected deaths) for whites and 68 (47/69) for blacks. White subjects had more than expected deaths from buccal cavity and pharynx (BCP) cancer [SMR = 388; 95% confidence interval (CI) = 125-905] and from esophageal cancer (SMR = 417; 112-1,067). Their lung cancer mortality rate was 50% higher than the rate of US white men and 14% higher than the rate of AL white men. Each of these three cancers has strong nonoccupational determinants, the roles of which were not assessed and which may have been responsible in whole or in part for the observed increases. The excesses of lung and esophageal cancer were concentrated among short-term employees, an observation which also argues against a causal link with occupational factors. Black men experienced no increased mortality from BCP, esophageal or lung cancer, but results for blacks were imprecise. For white and black subjects combined, there were 3 observed versus 0.62 expected deaths due to soft tissue sarcoma (p = 0.05). The job histories of subjects with this type of cancer did not suggest any shared occupational exposure.

Black or African American↗
PubMed1992

A case-control study of lung cancer at a dye and resin manufacturing plant.

This case-control study evaluated the relationship between lung cancer and occupational factors among employees at a dye and resin manufacturing plant. The study included 51 lung cancer cases and 102 controls who were members of a cohort of workers investigated in a previous retrospective follow-up study. Information on area of employment and on potential exposure to certain chemicals was obtained from plant personnel and medical records and from interviews with long-term employees. Information on potential confounders, including cigarette smoking, was obtained by interviewing study subjects or their next-of-kin. The odds ratio (OR) for heavy smokers compared with light or nonsmokers was 5.9 (95% confidence interval (CI) = 2.4-15). An elevated OR for lung cancer was observed for subjects who worked in the anthraquinone dye and epichlorohydrin manufacturing area of the plant (OR = 2.4; 95% CI = 1.1-5.2) and for employees who were seen at the plant infirmary for acute exposure to chlorine (OR, adjusted for smoking = 27; 95% CI = 3.5-205). Pipefitters employed at the plant for five or more years also had an elevated OR (3.3; 95% CI = 0.8-14).

Adult↗
PubMed1991

Endometrial cancer, obesity, and body fat distribution.

A case-control study was undertaken to evaluate the roles of obesity and body fat distribution in the etiology of endometrial cancer. The study also included an evaluation of the associations of serum estrone, estradiol, and androstenedione with obesity, body fat distribution, and endometrial cancer risk. The study included 168 cases and 334 control subjects identified at an optometry clinic. A strong, positive relationship between overall obesity and endometrial cancer was found. The relative rate of endometrial cancer for women in the upper 90th percentile of a body mass index compared to those below the median was estimated as 5.5 with 95% confidence limits of 3.2-9.6. There was no association between endometrial cancer and the waist to hip ratio, an index of upper versus lower body fat distribution. A statistical test of trend across the four quartiles of the waist to hip ratio yielded a P value of 0.45 after adjustment for confounding by the body mass index. On the other hand, there was a statistically significant, independent positive effect of a high subscapular to tricep skinfold ratio, a measure of central versus peripheral obesity, on endometrial cancer risk. The relative rates of endometrial cancer for the second, third, or fourth quartile compared to the first quartile of this index were 1.5, 1.9, and 2.7, respectively (P = 0.007), after adjustment for the body mass index. Serum estrone and estradiol, but not androstenedione, were statistically significantly correlated with the body mass index among control subjects (r = 0.37 and 0.40 for estrone and estradiol, respectively). On the other hand, each of the sex hormones was uncorrelated with the waist to hip ratio after adjustment for body mass. The correlations between each of the three hormones and the subscapular to tricep skinfold ratio among controls were weak and were not statistically significant (0.10, 0.10, and 0.14 for estrone, estradiol and androstenedione, respectively). Cases had statistically significantly higher mean serum estrogen and androstenedione levels than did controls and these elevations did not simply reflect a higher prevalence of obesity among them. The findings are equivocal with respect to fat patterns and endometrial cancer. We suggest that future epidemiological studies of cancer and body fat distribution more carefully distinguish among the various types of fat patterns.

Adipose Tissue↗
PubMed1991

An efficient program for computing conditional maximum likelihood estimates and exact confidence limits for a common odds ratio.

This paper describes a method and associated computer program for calculating exact confidence limits and P values, along with the conditional maximum likelihood estimate of the common odds ratio for a series of 2 x 2 tables. The program can be used to calculate exact estimates for matched data and is considerably faster than others currently available.

Algorithms↗
PubMed1990

A follow-up study of methods of contraception, sexual activity, and rates of trichomoniasis, candidiasis, and bacterial vaginosis.

A randomized, clinical trial was conducted to evaluate the spermicidal agent nonoxynol 9 as prophylaxis for sexually transmitted diseases. Eight hundred eighteen women using birth control who attended a sexually transmitted disease clinic were evaluated monthly for trichomoniasis, candidiasis, and bacterial vaginosis for 6 months. Women using the active spermicide experienced a somewhat lower incidence rate of trichomoniasis (relative rate 0.83; 95% confidence interval 0.61 to 1.12) and bacterial vaginosis (relative rate 0.86; 95% confidence interval 0.69 to 1.12) as compared with placebo users. The rate of candidiasis was nearly identical for spermicide and placebo users (relative rate 1.02; 95% confidence interval 0.77 to 1.35). The number of sexual partners during the preceding month was related directly to the occurrence of trichomoniasis (p = 0.047) and bacterial vaginosis (p = 0.009) but not candidiasis (p = 0.99). Subjects using oral contraceptives experienced a statistically significant lower rate of trichomoniasis than did women using an intrauterine contraceptive device or who had had a tubal ligation (relative rate 0.56; 95% confidence interval 0.39 to 0.81).

Adult↗
PubMed1989

Oral contraceptive use and the risk of chlamydial and gonococcal infections.

Oral contraceptive users were compared with nonusers with respect to the rate of cervical infections by Chlamydia trachomatis and Neisseria gonorrhoeae. The comparison was adjusted for differences in demographic and behavioral characteristics between the two groups. The rates of infection among oral contraceptive users were increased by approximately 70% (statistically significant) for both pathogens. Cervical ectopy was implicated in the increased rate of chlamydia but not gonorrhea. Rates of gonorrheal infection differed significantly among oral contraceptive formulations; rates were higher for formulations containing more androgenic progestins.

Adult↗
PubMed1989

Bias arising in case-control studies from selection of controls from overlapping groups.

Three examples are used to demonstrate that the selection of controls from categories that overlap can lead to bias. Case-control studies that use friend controls and the practice of age-matching controls to cases within a specified number of years (caliper matching) are examples of the selection bias described in the paper. The bias resulting from the use of friend controls can be large and, since the use of friend controls is common, this source of bias is of considerable practical consequence. The use of friend controls or the selection of controls according to other variables with categories that overlap should be avoided.

Age Factors↗