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C A Boyle

Publications and source records attributed to C A Boyle.

18 recordsLinked to original sources
PubMed1992

Proxy respondents and the validity of occupational and other exposure data. The Selected Cancers Cooperative Study Group.

As part of a multicenter cancer case-control study conducted in 1984-1988, a proxy interview was attempted for all cases who were initially interviewed for the study but who died during the 4-year data collection period. To assess the validity of using wives, other relatives, or other informants to obtain information about a subject, the authors compared occupational and other exposure data obtained from 270 male cancer cases and their proxy respondents. The primary focus of the case-control study was on Vietnam military service and exposure to phenoxy herbicides, but cases and their proxy respondents were also asked about occupational and other exposures relevant to the cancers. The accuracy of reporting for specific occupational exposures (e.g., asbestos and formaldehyde) and specific occupations (e.g., dry cleaning and meat packing or processing) was poor, although the latter improved somewhat when only case-spouse pairs were examined. Similarly, there was poor sensitivity in the reporting of herbicide exposure information in farming and other related occupations. In contrast, the reporting of certain demographic characteristics, childhood history characteristics, and use of alcohol and cigarettes was relatively good, and was even better when only case-spouse pairs were examined. The poor quality of proxy information for detailed exposure information suggests the need for careful use and interpretation of proxy information in epidemiologic studies.

Adult↗
PubMed1992

Self-reported health status of Vietnam veterans in relation to perceived exposure to herbicides and combat.

The authors examined how the self-reported health of 7,924 US Army Vietnam veterans in 1985-1986 related to the men's perceived exposure to herbicides and combat in Vietnam. The results showed strong, positive associations between the extent of reported herbicide exposure (classified as a four-level ordinal index) and all 21 health outcomes studied, with clear "dose-response" relations in most instances. In contrast, only chloracne and psychological symptoms, including a symptom pattern consistent with posttraumatic stress disorder, were found to be strongly related to the amount of reported combat exposure (classified as a four-level ordinal index). The multiple herbicide/outcome associations seem implausible because of their nonspecificity and because of collateral biologic evidence suggesting the absence of widespread exposure to dioxin-containing herbicides among US Army combat units. These associations may have resulted from long-term stress reactions that produced somatization, hypochondriasis, and increased utilization of medical care among some Vietnam veterans. The available data suggest, however, that the association between reported combat exposure and psychological symptoms consistent with posttraumatic stress disorder may be causal.

Germany↗
PubMed1992

The relation of computer-based measures of sperm morphology and motility to male infertility.

We investigated the relation between various sperm characteristics, including morphometric parameters, and impaired fertility among 596 men who participated in a national study. Semen was collected and processed by using a standardized protocol, and sperm measurements were made using a computer-aided sperm analysis instrument. We defined infertility in two ways: (1) the inability to father a child after trying for a year or longer, and (2) the number of children fathered. We found that all measures of sperm motion were decreased among men with impaired fertility. After adjustment for the other motion parameters and various potential confounders, however, only the percentage of progressive cells was associated with infertility. One morphometric parameter, the mean length/width ratio, was consistently associated with both measures of infertility, even after adjustment for potential covariates. This measure was also strongly associated with infertility among various subgroups defined by poor sperm concentration, motility, and morphology. The sperm length/width ratio appears to be an important correlate of infertility in males.

Adult↗
PubMed1991

Changes in oxygen saturation using two different sedation techniques.

Pulse oximetry was used to assess the degree of hypoxia observed in patients receiving simple midazolam sedation for removal of lower third molars and compared to that seen in patients receiving a combination sedation technique using nalbuphine and midazolam. Results showed that the degree of hypoxia experienced by patients receiving the combination technique was significantly more profound in both incidence and depth than that seen in the group receiving midazolam alone (p less than 0.05).

Procedural Sedation↗
PubMed1991

Non-Hodgkin's lymphoma in a cohort of Vietnam veterans.

We examined the incidence of non-Hodgkin's lymphoma (NHL) in a cohort of 18,313 United States Army veterans from the Vietnam era. Diagnoses were confirmed through a review of hospital records. Among veterans who had died after discharge or who had participated in a telephone interview (8,170 Vietnam veterans and 7,564 non-Vietnam veterans), seven Vietnam veterans and one non-Vietnam veteran had developed non-Hodgkin's lymphoma (p = 0.07). As none of the NHL cases had military job titles which suggest that they were occupationally exposed to herbicides while in Vietnam, the reasons for the excess are unclear.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1990

National sources of vital status information: extent of coverage and possible selectivity in reporting.

The completeness of death reporting and characteristics of deaths not found by the Social Security Administration, Internal Revenue Service, Veterans Administration, and National Death Index were investigated in a follow-up study (1965-1983) of mortality among 18,313 randomly selected Vietnam-era veterans. Overall, 97% of all known deaths identified by these means had been found by the National Death Index (for the years 1979-1983), 83% by the Social Security Administration files, 80% by the Veterans Administration file, and only 23% by the Internal Revenue Service file. Coverage by the Veterans Administration file differed considerably by time period of death; 28% of deaths occurring in 1965-1971 appeared in the Veterans Administration system compared with 87% in 1972-1983. Social Security Administration coverage varied somewhat over time-87% in the period from 1965-1981 and 64% in 1982-1983. Deaths not found by the National Death Index or the Veterans Administration file occurred more frequently among those with certain characteristics, such as nonwhite racial background, nonhonorable discharge, and low rank at discharge. There were no such differences for deaths found by the Social Security Administration. Importantly, these characteristics were strong predictors of subsequent mortality. Thus, in studies of mortality, there is a potential for bias when certain reporting sources are used to the exclusion of others.

Cohort Studies↗
PubMed1990

Estimating the number of suicides among Vietnam veterans.

Unconfirmed reports that 50,000 or more Vietnam veterans have committed suicide give the impression that these veterans are at exceedingly high risk of suicide compared with other veterans and nonveterans of the same age. On the basis of projections from two population-based mortality studies, the authors estimate that fewer than 9,000 suicides occurred among all Vietnam veterans from the time of discharge through the early 1980s. The sixfold or greater relative risk of suicide implied by the unsubstantiated suicide death tolls is also demonstrated to be incompatible with the findings of epidemiologic studies of mortality risk among Vietnam veterans.

Adult↗
PubMed1989

Are racial differences in the prevalence of diabetes in adults explained by differences in obesity?

To determine whether the higher prevalence of diabetes found among blacks in the United States is explained by racial differences in obesity, we examined the prevalence of diabetes adjusted for adiposity, education, and income in a cohort of US Army veterans from the Vietnam era. Among 12,558 white men and 1677 black men, aged 30 to 47 years, blacks were more likely than whites to have diagnosed diabetes (adjusted prevalence ratio, 1.9; 95% confidence interval, 1.3 to 2.7). Within every age, adiposity, and socioeconomic stratum, blacks had a higher prevalence of diagnosed diabetes than whites. In a subgroup of veterans for whom fasting serum glucose values were measured, blacks were more likely than whites to have fasting hyperglycemia (fasting serum glucose value greater than or equal to 7.8 mmol/L) (adjusted prevalence ratio, 5.7; 95% confidence interval, 2.7 to 12.0). These data provide evidence that the higher prevalence of diabetes found among blacks is not explained by differences in obesity.

Adult↗
PubMed1989

Cervical intraepithelial neoplasia among women with papillomavirus infection compared to women with Trichomonas infection.

This study was undertaken to determine if women with papillomavirus infection were more likely to develop cervical intraepithelial neoplasia (CIN) than women with other sexually transmitted infections. Women with cytologic evidence of papillomavirus infection and a comparison group of women with cytologic evidence of Trichomonas infection were identified from a reexamination of cervicovaginal smears initially evaluated between 1973 and 1981 in a private pathology laboratory. To identify subsequent CIN among these women the authors reviewed records of private obstetric and gynecology practices and public clinics through 1983. After accounting for possible confounding variables, including age, marital status, frequency of cervical cytologic examination, and selected characteristics of pregnancy history, a 2.7-fold increase in the rate of CIN was found among the 613 women with prior papillomavirus infection compared to the 410 women with previous Trichomomas infection. The rate ratio was higher among women with more severe cervical neoplasia than for those with less severe neoplasia and for those followed for greater than 12 months than for those followed 7 to 12 months. The results of this study provide further evidence of the role of papillomavirus in the etiology of cervical cancer.

Adult↗
PubMed1989

Bias associated with differential hospitalization rates in incident case-control studies.

Berkson's bias reflects a statistical phenomenon in which differential hospitalization rates create an exposure distribution among hospitalized cases that differs from that among other cases. Importantly, previous work on Berkson's bias has not explicitly addressed the possibility of excluding prevalent or previously diagnosed cases--exclusions that are key features of many study designs. We indicate that the classically described bias differs from the corresponding bias in studies, such as incidence density studies, in which cases are restricted to those with recent diagnoses. We present methods that may be used to assess the magnitude of Berkson's bias in incidence-density studies. In many, though not all, situations the bias should be small and of little practical concern.

Epidemiologic Methods↗
PubMed1989

Validity of death certificates for injury-related causes of death.

Exploration of the validity of death certificate information for classifying underlying causes of death has historically focused on "natural" or disease-related causes of death. Current interest in injury-related deaths has emphasized the need for proper certification and coding of these deaths. In this study, the authors compared agreement of the underlying cause of death as determined from death certificate information with that determined from an independent review of all relevant medical and legal documents of death by a panel of physicians. The study sample included all deaths (n = 446) occurring over an approximately 18-year follow-up period (1965-1983) in a randomly selected cohort of 18,313 US Army Veterans of the Vietnam era. Using the physician panel as the "gold standard," sensitivity and specificity were 90% or greater for broad groupings of motor vehicle crash deaths (International Classification of Diseases, Ninth Revision (ICD-9), codes E810-E825), suicides (codes E950-E959), and homicides (codes E960-E969). Agreement for deaths from unintentional poisonings (codes E850-E869), mostly drug- and alcohol-related, was poor (sensitivity, 50 percent); in general, the ICD-9 drug- and alcohol-specific nomenclature is difficult to apply. The specificity and sensitivity for the individual three-digit suicide and homicide codes were all greater than 90%, and although the specificity for three-digit motor vehicle crash deaths was also above 90%, the sensitivity was lower, from 29% to 83%. Agreement on the fourth digit of ICD-9--for example, the role of the decedent in a motor vehicle crash death--was generally poor. The lack of descriptive information on death certificates to allow detailed coding was chiefly responsible for the poor agreement.

Adolescent↗
PubMed1987

Underreporting of alcohol-related mortality on death certificates of young US Army veterans.

We assessed the validity of death certificate data for alcohol-related mortality in a population-based follow-up study of young, male US Army veterans. In a random sample of more than 18,000 men who entered the service between 1965 and 1971, there were 446 postservice deaths through Dec 31, 1983. For 426 of these deaths, we obtained both the death certificate and all other available medical and legal records pertaining to cause of death. A nosologist recorded each death certificate in accordance with the ninth revision of the International Classification of Diseases. A medical panel, without having access to the death certificates, assigned underlying and contributory causes of death on the basis of a review of only the medical and legal records. The panel recorded 133 alcohol-related deaths, or more than six times the number (21 deaths) determined by the original death certifiers. Omission of elevated blood alcohol levels in deaths due to injury accounts for most of the underreporting of alcohol-related mortality on the death certificates. Our findings suggest that death certificate data grossly underestimate the contribution of alcohol to mortality, especially in the area of injury, and the validity of official vital statistics for alcohol-related deaths would be enhanced if death certifiers incorporated all available antemortem and postmortem diagnostic information.

Adult↗
PubMed1987

Epidemiology of premenstrual symptoms.

We examined the prevalence of selected premenstrual symptoms among 520 Connecticut women in relation to demographic, reproductive, contraceptive, and medical characteristics. The prevalence ranged from 39 per cent for breast swelling to 81 per cent for premenstrual weight gain. Socioeconomic status, race, history of benign breast disease, bra cup size, and history of abortions were some of the factors associated with premenstrual symptoms.

Adult↗
PubMed1986

Abortion before first livebirth and risk of breast cancer.

The present study examined the association between abortion prior to a first livebirth and breast cancer risk among a cohort of 3,315 women who had been delivered of liveborn children between 1946 and 1965 in a group of private gynaecology practices in Connecticut and followed through 1980 for the incidence of cancer. Among women with one livebirth at the time of cohort identification, a spontaneous abortion before this livebirth was associated with a 3.5-fold increase in the risk of breast cancer. The elevation in risk was independent of some of the major risk factors of breast cancer and became more pronounced as the number of years since the abortion increased.

Abortion, Spontaneous↗
PubMedDate not supplied

Reproducibility of the cytologic diagnosis of human papillomavirus infection.

As part of a larger epidemiologic investigation of the association between human papillomavirus (HPV) infection and cervical intraepithelial neoplasia, the reliability of the cytologic diagnosis of HPV infection was examined. A random sample of cervicovaginal specimens with cytologic changes characteristic of HPV infection were matched with a second set of slides, with regard to the date and severity of the smear and the age of the woman from whom the smear was obtained. The kappa statistic for interobserver agreement was 0.38 (p less than 0.0005), increasing to 0.68 (p less than 0.0005) when uncertain diagnoses were excluded. Intraobserver agreement ranged from kappa = 0.40 to 1.00. Although this agreement is within the range of reliability found for the diagnosis of other atypical cytologic changes, considerable variation is present. The effect of this variability on the validity of estimating the risk of cervical cancer associated with HPV infection may be considerable.

Cervix Uteri↗