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Biomedical subjects

T Colton

Publications and source records attributed to T Colton.

At least 19 recordsLinked to original sources
PubMed1991

Increased risk of profound weight loss among women exposed to diethylstilbestrol in utero.

We surveyed 1711 women exposed to diethylstilbestrol in utero, and 919 women not exposed, concerning lifetime weight loss histories. The prevalence of a history of unexplained profoundly low body weight (weight less than or equal to 80% of expected weight for age, sex, and height) was 18.7 per 1000 in the exposed group compared to 3.3 per 1000 in the unexposed group; a 5.72 to 1 ratio of increased risk.

Adult↗
PubMed1991

Issues in the early termination of the aspirin component of the Physicians' Health Study. Data Monitoring Board of the Physicians' Health Study.

The Physicians' Health Study is a randomized, double-blind, placebo-controlled prevention trial of 22,071 US physicians, using a factorial design to evaluate the role of aspirin in the prevention of cardiovascular mortality and beta carotene in the reduction of cancer incidence. After approximately 5 years of follow-up, the aspirin component was terminated, 3 years ahead of schedule. Several factors were considered in the decision to terminate, including a cardiovascular mortality rate markedly lower than expected in both aspirin and placebo subjects, precluding the evaluation of the primary aspirin hypothesis, and a highly significant (P < .00001) and impressive (44%) reduction in the risk of first myocardial infarction in the aspirin group. Issues in the decision to terminate are described in this report.

Adult↗
PubMed1991

Cancer surveillance of Veterans in Massachusetts, USA, 1982-1988.

This surveillance study is a follow-up to previous findings of elevated soft tissue sarcoma mortality in Massachusetts Vietnam veterans compared to other veterans. The roster of veterans was compiled from Massachusetts residents who received a state bonus for military service in the period 1958-1973. This computerized list was linked to the central files of the Massachusetts Cancer Registry and cases diagnosed between 1982 and 1988 were identified. Odds ratios (ORs) for several cancer sites were computed; only that for soft tissue sarcoma incidence was significantly elevated in Vietnam veterans compared to other veterans (OR = 3.08; 95% confidence interval: (CI) 1.07-8.73). Kaposi's sarcoma cases who were also AIDS patients were excluded from the analysis. Non-Hodgkin's lymphoma was also investigated but was not significantly elevated in these surveillance data. Sources of bias are discussed and recommendations for continued surveillance and follow-up studies are made.

Adult↗
PubMed1989

A two-period crossover design for the comparison of two active treatments and placebo.

This paper discusses a two-period crossover design for the comparison of two active treatments (A and B) and placebo (P) for relief of recurrent symptoms of a chronic health disorder. It is based on blocks of ten patients for which the treatment sequences A:B and B:A are each assigned to three patients and the sequences A:P, P:A, B:P, and P:B are each assigned to one patient; thus, treatment periods have a 2:2:1 allocation for A, B, and P. The principal model for analysis of this design involves additive subject effects, period effects, and treatment effects. Analysis of within-patient differences provides an estimate of the comparison between active treatments with variance (2vw/7r) and an estimate of the comparison between an active treatment and placebo with variance (4vw/7r); here vw is the within-patient variance and r is the number of blocks of ten patients. Analyses which address carryover effects and treatment effects adjusted for carryover effects are also described. An example using simulated data on relief of recurrent gastrointestinal pain illustrates the methodology.

Chronic Disease↗
PubMed1989

Prevention of childhood injuries: evaluation of the Statewide Childhood Injury Prevention Program (SCIPP).

We evaluated the effectiveness of a community-based injury prevention program designed to reduce the incidence of burns, falls in the home, motor vehicle occupant injuries, and poisonings and suffocations among children ages 0-5 years. Between September 1980 and June 1982, we implemented five injury prevention projects concurrently in nine Massachusetts cities and town; five sites, matched on selected demographic characteristics, were control communities. An estimated 42 percent of households with children ages 0-5 years were exposed to one or more of the interventions over the two-year period in the nine communities. Participation in safety programs increased three-fold in the intervention communities and two-fold in the control communities. Safety knowledge and practices increased in both intervention and control communities. Households that reported participatory exposure to the interventions had higher safety knowledge and behavior scores than those that received other community exposure or no exposure to intervention activities. We found a distinct reduction in motor vehicle occupant injuries among children ages 0-5 years in the intervention compared with control communities, associated with participatory exposure of about 55 percent of households with children ages 0-5 years. We have no evidence that the coordinated intervention programs reduced the other target injuries--although exposure to prevention messages was associated with safety behaviors for burns and poisonings.

Accident Prevention↗
PubMed1988

A prospective randomized trial of outpatient versus inpatient cardiac catheterization.

To evaluate the safety and cost of outpatient cardiac catheterization, we conducted a randomized trial at three hospitals of outpatient (n = 192) as compared with inpatient (n = 189) cardiac catheterization in low-risk patients. Outpatients had the following complication rates as compared with inpatients: hematoma, 12 versus 8.5 percent; numbness or weakness of extremity, 0.5 versus 1.6 percent; cold or blue extremity, 1.6 versus 1.1 percent; and acute myocardial infarction, 1.6 versus 0.5 percent. None of these differences were statistically significant. No deaths or strokes occurred in either group. Twenty-three patients (12 percent) assigned to the outpatient group required hospitalization because of complications of catheterization. In the outpatient group, the relative risk for hematoma was 1.42 (95 percent confidence interval, 0.77 to 2.29), and the relative risk for myocardial infarction within one week was 2.95 (95 percent confidence interval, 0.3 to 28.1). There were no significant differences between the two groups in whether they resumed normal activities or in the rates of rehospitalization within one week of the procedure. Total catheterization-related charges per patient were $679 lower for outpatients, with a savings in total hospital charges (including charges for subsequent therapeutic procedures) of $885 per patient. We conclude that elective cardiac catheterization as an outpatient procedure for selected patients is feasible and safe. Given the small size of our sample, however, we urge caution in interpreting these findings, since they do not exclude a small increase in complication rates with outpatient cardiac catheterization.

Ambulatory Care↗
PubMed1988

Forced vital capacity and the risk of hypertension. The Normative Aging Study.

This report describes the development of hypertension among 1,270 males (aged 23-80 years at the time of entry into the study) observed prospectively for 10 years who had a baseline blood pressure of less than 140/90 mmHg and who underwent baseline spirometry. Subjects were participants in the Normative Aging Study, a longitudinal study on aging initiated in 1961 at the Veterans Administration Outpatient Clinic in Boston, Massachusetts. Blood pressures were taken at five- and 10-year follow-up examinations. The age-adjusted incidence of hypertension during the follow-up period was found to be inversely related to forced vital capacity. Multiple logistic regression was employed to assess the relation of forced vital capacity to the subsequent development of hypertension after controlling for baseline levels of age, weight, cigarettes smoked per day, and systolic and diastolic blood pressures. Forced vital capacity was a statistically significant and negative predictor, indicating that lower values of forced vital capacity were associated with the subsequent development of hypertension. This was consistently found in several logistic regression analyses with a standardized odds ratio associated with forced vital capacity of approximately 0.7. Although the physiologic mechanism for this association is unknown, these findings may have importance in identifying subjects at risk and may also provide insight into disease pathogenesis.

Adult↗
PubMed1987

Health problems reported by residents of a neighborhood contaminated by a hazardous waste facility.

A symptom prevalence survey was conducted of a neighborhood exposed to airborne hazardous wastes. Residents' responses were compared to those of a nearby control population. The results revealed that the exposed group had more self-reported complaints referable to the respiratory system (wheezing, shortness of breath, chest discomfort, persistent colds, coughs), constitutional complaints (always fatigued, bowel dysfunction), and irregular heart beat. When the effect of a documented irritant source in a small portion of the control population was removed, the exposed group also complained more often of irritation of the eyes and nose. There was a biological gradient for several of these effects. Efforts to eliminate the influence of confounding and recall bias are discussed. The results suggest either that the general population reacts to chemicals at levels much lower than the available occupational literature would indicate or that the effects are more long lasting than previously thought.

Adolescent↗
PubMed1987

The relationship of nonspecific bronchial responsiveness to the occurrence of respiratory symptoms and decreased levels of pulmonary function. The Normative Aging Study.

Nonspecific bronchial responsiveness was assessed by an abbreviated methacholine challenge test in 458 male participants of the Normative Aging Study, who also completed a respiratory questionnaire and spirometry. A positive response to the methacholine challenge test was defined as a greater than or equal to 20% decline in FEV1 during the test. Cigarette smoking was significantly associated with a positive methacholine response (p less than 0.001). Logistic regression analyses indicated that there was a significant association between a positive response to methacholine and both any wheeze (p = 0.002) and persistent wheeze (p less than 0.001) after taking into account smoking status and age; an association between responsiveness and chronic cough was of borderline significance (p = 0.06). Multiple linear regression analyses indicated that positive methacholine responsiveness was independently associated with lower levels of FEV1 (p less than 0.001) and FEF25-75 (p less than 0.001). Using the log of the dose-response slope rather than a dichotomous variable to characterize responder status yielded very similar results in the linear and logistic models. The findings of this cross-sectional study suggest that increased level of nonspecific responsiveness is significantly associated with wheeze and cough symptoms and decreased levels of pulmonary function in adult men. Longitudinal follow-up of these men should shed light on the importance of nonspecific responsiveness as a risk factor for the subsequent development of chronic obstructive pulmonary disease.

Adult↗
PubMed1987

Vasoactive neurochemicals identified in omentum: a preliminary report.

There has been increasing interest in biologic, immunologic, and chemical activity originating from omental tissue. Since clinical improvement has been observed in some patients very shortly after surgically transposing their omentum to the spinal cord or brain, the question arose as to whether neurochemicals might be present in omental tissue; a possible explanation for some of these neurological changes. This paper reports the presence of vasoactive neurochemicals in canine omental tissue. It remains unclear, however, whether the omentum produces or simply concentrates these and other neurochemicals.

Animals↗
PubMed1986

Qualitative overview of randomized trials of aminoglycosides.

A qualitative overview was conducted of randomized clinical trials comparing two or more of the following aminoglycoside antibiotics--amikacin. gentamicin, netilmicin, sisomicin, and tobramycin--with respect to efficacy, nephrotoxicity, or auditory toxicity. Design features considered included number of participants in each treatment arm, proportion of randomized participants available for analysis, blinding of evaluators, and report of statistically significant results. The proportion of participants eligible for analysis was less than or equal to 75 percent for 66 percent of the comparisons regarding nephrotoxicity, 43 percent regarding efficacy, and 19 percent regarding auditory toxicity. Twenty-nine percent of the trials reported that evaluators were blinded to treatment group assignments. The results of most trials showed no significant differences, although sample sizes were, in general, smaller than necessary to detect moderate differences. Quantitative overviews may be a useful means of detecting real differences in risk that are not apparent from the results of several individual small trials.

Amikacin↗
PubMed1985

A comparison of pregnancy history recall and medical records. Implications for retrospective studies.

Using data from the Diethylstilbestrol-Adenosis (DESAD) Project, a study of the effects of diethylstilbestrol (DES) exposure during fetal life, the authors compared prenatal records with obstetric history from mother's questionnaires completed 10 or more years after the birth of their daughters. Except for the history of hospitalization and trunk x-ray, no differences were observed in agreement (questionnaire compared with record) between the group of DES-exposed mothers identified through review of their prenatal records and the comparison group of mothers who were not exposed. The authors also compared data from mothers of DES-exposed daughters who initiated their own enrollment in the study (walk-ins and referrals). To obtain prenatal records for these women, physicians were contacted. They would usually supply drug exposure data but not the other obstetric history requested. Mothers of these walk-ins and referrals had slightly better agreement between questionnaire and records when compared with the two groups identified by review of prenatal records. In general, there was good to excellent agreement for all groups when mothers' recall of personal history (past miscarriage, past pregnancy, etc.) was compared with their medical records. However, for medical intervention such as drugs and x-rays, agreement was poor. Of the DES-exposed mothers identified through review of their prenatal records, 29% could not remember whether they took DES. An additional 8% said they did not take DES when it was recorded in their charts.

Clinical Trials as Topic↗
PubMed1985

An investigation of bias in a study of nuclear shipyard workers.

The authors examined discrepant findings between a 1978 proportional mortality study and a 1981 cohort study of workers at the Portsmouth, New Hampshire, Naval Shipyard to determine whether the healthy worker effect, selection bias, or measurement bias could explain why only the proportional mortality study found excess cancer deaths among nuclear workers. Lower mortality from noncancer causes in nuclear workers (the healthy worker effect) partly accounted for the observed elevated cancer proportional mortality. More important, however, was measurement bias which occurred in the proportional mortality study when nuclear workers who had not died of cancer were misclassified as not being nuclear workers based on information from their next of kin, thereby creating a spurious association. Although the proportional mortality study was based on a small sample of all deaths occurring in the cohort, selection bias did not contribute materially to the discrepant results for total cancer deaths. With regard to leukemia, misclassification of occupation in the proportional mortality study and disagreement about cause of death accounted for some of the reported excess deaths.

Epidemiologic Methods↗
PubMed1985

Health experiences of operating room personnel.

In an attempt to evaluate health experiences of operating room personnel using previously published reports, the authors calculated summary relative risks (RRs) for each outcome under investigation by combining data from six studies. For each summary RR, they also calculated 95% confidence limits; when the range of the confidence interval excludes 1.0, the increased risk is statistically significant at the 0.05 level. The most consistent evidence was for spontaneous abortion among pregnant physicians and nurses who work in operating rooms, where the RR was 1.3 (95% confidence limits from 1.2 to 1.4). For liver disease there were statistically significant increased RRs among both men (1.6, 1.3-1.9) and women (1.5, 1.2-1.9), but these were based on smaller numbers of studies. Although the results of pooled analyses are suggestive, most studies of this issue have relied on voluntary responses and self-reported outcomes, so that response and/or recall bias could explain these findings. In addition, these investigations generally have examined working in operating rooms rather than actual exposure to anesthetic gases. Finally, there have been considerable improvements in operating room scavenging systems during the last decade. Thus, prospective cohort studies are needed to determine whether there is a relationship between current levels of occupational exposure to anesthetic gases and adverse outcomes, particularly spontaneous abortion and liver disease.

Abortion, Spontaneous↗
PubMed1984

Breast cancer in mothers given diethylstilbestrol in pregnancy.

We compared the incidence of breast cancer in 3033 women who had taken diethylstilbestrol (DES) in pregnancy during the period from 1940 to 1960 with the incidence in a comparable group of unexposed parous women. We ascertained vital status in 95 per cent of the exposed women and in 93 per cent of the unexposed women and received completed questionnaires for 88 and 85 per cent, respectively. With over 85,000 woman-years of follow-up in each group, the incidence of breast cancer per 100,000 woman-years was 134 in the exposed group and 93 in the unexposed group, yielding a crude relative risk of 1.4 (95 per cent confidence interval, 1.1 to 1.9). The elevated incidence did not appear to be due to bias or to confounding by other risk factors measured in the study. Breast-cancer mortality was slightly higher in the exposed women (relative risk, 1.1) but not significantly so (95 per cent confidence interval, 0.7 to 2.0). We conclude that the incidence of breast cancer is moderately increased in women given DES, but we cannot exclude the possibility that some unrecognized concomitant of DES exposure accounts for this increase.

Actuarial Analysis↗