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Biomedical subjects

W O Spitzer

Publications and source records attributed to W O Spitzer.

At least 73 records · Page 4Linked to original sources
PubMed1989

Body size and breast cancer prognosis: a statistical explanation of the discrepancies.

A historical cohort of 68 female breast cancer patients from one institution who were enrolled in a multicenter randomized controlled trial between 1971 and 1973 were followed up to the beginning of 1986. Weight and height at the time of mastectomy were transformed into two indices of body size, namely the Quetelet Index and a weight to "ideal weight" ratio. These two indices were analyzed for their relation with overall and disease-free survival, while controlling for the effect of several potential confounding variables. While neither index was linearly related to the hazard of death or recurrence, a significant quadratic (curvilinear) relation was found for both indices and both hazards. In all cases the hazard function was concave up, indicating that not only overweight but also underweight status is predictive of an unfavorable prognosis of breast cancer. This finding offers a possible explanation for the discrepancies among previous studies on this topic.

Adult↗
PubMed1989

Respiratory health of a population living downwind from natural gas refineries.

Since 1958 there has been a perception of excess illness in a rural Canadian population living downwind from two natural gas refineries, the emissions of which contain mostly sulfur dioxide but also hydrogen sulfide. To determine if there was an excess of adverse health outcomes in the population exposed (defined by place of residence), a health survey was undertaken in 1985 in this area and in one unexposed to emissions but demographically similar. Participation was 92% from both the exposed population (n = 2,157) and a representative sample (n = 839) of the main reference population. More respiratory symptoms were reported in the exposed group than in the non-exposed group among those 5 to 13 yrs of age (28% versus 18%) and among never-smokers greater than or equal to 14 yrs of age (35% versus 24%). FEV1, FVC, and FEV1/FVC were similar in both areas. Dichotomizing the level of exposure (high, low) within the exposed area revealed a trend in the high exposure area toward increased respiratory symptoms in the younger age group (39% versus 24%), but decreased symptoms in the older age group (33% versus 36% among never-smokers). FEV1 was similar between the two areas. The excess of respiratory symptoms in the exposed area unassociated with impaired spirometric values would be compatible with increased awareness of health or a small biologic environmental effect.

Child↗
PubMed1989

The influence of psychological status on respiratory symptom reporting.

The American Thoracic Society respiratory symptom questionnaire (ATS-Q) is widely used and has provided valuable information in epidemiologic studies. To determine the influence of psychological status on respiratory symptoms, we compared subjects' ATS-Q responses to their Ilfeld Psychiatric Symptom Index (PSI) scores. To minimize the potential confounding effect of respiratory disease on the association between respiratory and psychological status, from a population-based survey of 3,628 subjects, we studied only the 600 "healthy" subjects, defined by the following characteristics: between 14 and 55 yr of age; never-smokers; no diagnoses of respiratory, heart, kidney, thyroid disease, or anemia; and normal spirometry (defined as an FEV1 and FVC greater than 80% of predicted). Associations were found between respiratory symptoms (cough, phlegm, wheeze, dyspnea) and PSI subscales (anxiety, anger, depression, and cognitive disturbance). Adjusted odds ratios for respiratory symptoms ranged from 1.13 to 2.15 for every 10% increase in PSI score. Psychological status is an important determinant of respiratory symptoms and therefore must be taken into consideration when interpreting results of epidemiologic studies using questionnaire information.

Adolescent↗
PubMed1989

Cancer downwind from sour gas refineries: the perception and the reality of an epidemic.

A rural population in southwestern Alberta, Canada, living downwind from natural gas refineries, has expressed concerns about an excess of adverse health outcomes over the last 25 years. This has escalated to the point of causing a prominent sociopolitical controversy within the province. As part of a large field epidemiologic study undertaken during the summer of 1985 to investigate possible health effects, a residential cohort study was carried out to study cancer incidence. The cohort was defined as all those individuals who resided in the area in 1970. A total of 30,175 person-years of risk within Alberta were experienced by this cohort from 1970 to 1984. The incident cancers during this period were enumerated by computerized record linkage with the Alberta Cancer Registry. Age- and sex-standardized incidence ratios, based on expected rates from three prespecified demographically similar, nonmetropolitan Southern Alberta populations, were 1.05, 1.09, and 1.03, respectively, none of which was significantly different from unity. Although they do not address the issue of etiologic association, these data can provide considerable reassurance to a community that was convinced it had experienced an epidemic of cancer.

Acid Rain↗
PubMed1988

Clinical interpretation of airway response to a bronchodilator. Epidemiologic considerations.

Airways responsiveness to a bronchodilator is frequently measured to assist in determining the cause of respiratory symptoms. Clinically, a greater than 15% improvement in the FEV1 is often used to define the "increased" response indicative of asthma. However, unlike other tests of lung function, reference standards derived from "healthy" members of a general population sample have never been reported. As part of a health survey carried out in Alberta, Canada, 2,609 subjects completed a standardized respiratory symptom questionnaire and had FEV1 measured before and 20 min after inhaling terbutaline sulfate via a 750-ml spacer device. Among asymptomatic never-smoking subjects with a FEV1 greater than 80% of predicted, the upper 95th percentile of bronchodilator response (BDR), when expressed as 100 x (FEV1 postBDR - FEV1 preBDR)/predicted baseline FEV1 averaged 9%. This value remained remarkably stable across gender, age (7 to 75 yr), and height groups, and deviated to 6% only when baseline FEV1 was greater than 120% of predicted. Consistent with other respiratory function variables, in which the upper limit of normal is often defined as the upper 95th percentile, our population-derived reference values provide a conceptual definition of BDR that can easily be applied to define "increased" response in the clinical setting.

Adolescent↗
PubMed1988

Application of an Euclidian distance measure to the selection of reference areas in epidemiologic research concerning environmental issues.

A procedure for selecting reference areas in epidemiologic research employing census data and squared Euclidian distance is described. The procedure was adapted from cluster analysis, a multivariate statistical technique that has been applied in many disciplines. With the use of 12 census variables as the basis for evaluating sociodemographic differentiation, squared Euclidian distances were calculated between a geographically delineated index area in southwest Alberta, where residents had complained for several years about the effects of exposure to sour gas emissions, and 119 provincial census tracts in the rest of nonmetropolitan southern Alberta. The Euclidian distances can be interpreted as social distance scores with values close to zero representing a high level of sociodemographic similarity between the index area and potential reference areas. The social distance scores, in association with environmental data, suggested a clear choice for the most comparable unexposed reference area and illustrated the difficulty of finding a suitable most comparable exposed reference area. Results from the demographic component of the subsequent health survey indicated that the index area and reference area were similar in most respects. Furthermore, tests with and without statistical adjustment for confounding variables produced negligible differences on most of the important target outcome variables.

Adolescent↗
PubMed1988

Methylmercury and the health of autochthons in northwest Quebec.

We conducted a cross-sectional epidemiologic and clinical study to evaluate the nature, magnitude, and frequency of unfavourable health states among residents of northwest Quebec. Of particular interest were the possible occurrence of Minamata disease and any other neurological abnormalities. We also sought to determine whether industrial or naturally-occurring mercury in the region's environment were causally associated with any disorders that might be detected. A total of 321 subjects were studied in four groups with contrasting exposure to point-source mercury from a chlor-alkali plant in the area. Methylmercury in hair served as the marker of subject's ingestion of any organic mercury (natural or industrial). Ten pre-chosen target variables, seven clinical and three neurophysiological, were assessed in all subjects. Relationships between mercury in hair and each target variable were calculated. We determined whether gradients in target variables corresponded to gradients in potential exposure of the subjects to the aquatic emissions of the chlor-alkali plant. Minamata disease was not found. Diabetes and alcohol-related health problems assessed as important clinically plausible confounders, were common. Differences in frequency or magnitude of clinical, toxicological, and physiological findings among the contrast groups were small and not of clinical or statistical significance. There were definite relationships between mercury in hair and four target variables despite the low values of mercury measured and the mild nature of the health problems observed. This would suggest that verifiable biological threshold levels for clinical effects, if such exist, may be substantially lower among Canadians than those currently adopted as policy for adults elsewhere. A gradient was found only for two of the ten target variables. Clinically meaningful alternate hypotheses for observed health effects emerge in the data and agree with observations in the field made by consulting clinical experts.

Animals↗
PubMed1988

Assessment of global function: The Reintegration to Normal Living Index.

This paper reports the development of an instrument, the Reintegration to Normal Living (RNL) Index, to assess global function status. Information to determine the components of the index was systematically collected through interviews with professionals, patients, and their significant others, promoting content validity. Psychometric properties of the index were assessed using three samples of patients with varied diagnoses from several settings. The index demonstrates high internal consistency and adequate interrater reliability (patient and significant other). It is responsive to changes in the clinical status of patients, particularly when the subscales of Daily Living and Perceptions of Self are considered. In terms of criterion validity, the index is somewhat related to work status and disease status. It also demonstrates construct validity, both convergent and discriminant, when assessed against a quality of life index and an index of psychologic well-being. The RNL index appears to assess global function and measures both the patient's perceptions of their own capabilities and objective indicators of physical, social, and psychologic performance.

Activities of Daily Living↗
PubMed1987

Perceived discrimination against cured cancer patients in the work force.

To evaluate perceived discrimination against cured cancer patients in the work force in Montreal, in 1982-83 we surveyed 101 cured cancer patients and 101 control subjects who had never had cancer and who were matched for age, sex and neighbourhood of residence. In addition, 24 of the cured patients were randomly selected and paired with cancer patients with a poor prognosis who were matched for age and sex. Discrimination was slightly more common among cured patients (18%) than among control subjects (15%), and 21% of the cancer patients with a poor prognosis reported discrimination. Analysis of the comparisons between the cured and control groups indicated no statistically significant differences. The cured cancer patients reported the following problems faced by cancer patients returning to work: fatigue (30%), absenteeism (14%), psychologic problems (12%), social stigma (12%) and discrimination by an employer (10%).

Adult↗
PubMed1987

The role of the NH2-terminal portion of pro-opiomelanocortin as a biomarker for human lung cancer.

In an epidemiological study, we evaluated the human amino-terminal portion (IR-hNT) of pro-opiomelanocortin (POMC) as a biomarker for lung cancer by measuring it by radioimmunoassay in the plasma of 180 patients with various histological types of pulmonary carcinoma. Seventy-seven patients with other cancers or benign lung disorders were our controls. An elevated IR-hNT level was measured in 12 percent of the lung neoplasm cases (22% in small-cell carcinoma) and in only 6 percent of the controls. The mean level in the lung cancer group was also higher than in the controls (p = 0.004), while it was higher in patients with small-cell carcinoma than in those with squamous-cell and adenocarcinoma (p = 0.013 and 0.002, respectively). Otherwise, we demonstrated a correlation between IR-hNT levels and altered liver function only in patients with a lung malignancy (p varying between 0.015 and less than 0.001). Finally, survival analysis failed to show that IR-hNT has a prognostic value when measured at the onset of lung cancer. These results allow us to conclude that IR-hNT, although not very sensitive in screening for carcinoma of the lung, may indicate the presence of liver metastases in this disease.

Adrenocorticotropic Hormone↗