Search PubMed⌕ Search

Biomedical subjects

K C Johnson

Publications and source records attributed to K C Johnson.

At least 19 recordsLinked to original sources
PubMed2002

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease.

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Adult↗
PubMed2002

Health Opportunities with Physical Exercise (HOPE): social contextual interventions to reduce sedentary behavior in urban settings.

Physical activity interventions targeting social and physical environments of the urban poor hold promise in improving health outcomes in underserved communities. This study randomly assigned overweight, sedentary, economically disadvantaged adults to one of three intervention conditions at The Hope and Healing Center, a large inner-city health facility providing numerous options for exercise. Within the tenets of Social Action Theory, the Health Opportunities with Physical Exercise (HOPE) trial will test the efficacy of two behavior change models, social support and patient-provider interaction, to increase physical activity. In addition to a standard care condition, in which patients have open access to Hope and Healing physical activity programming, patients were assigned to one of two behavior change interventions. Those assigned to patient-peer receive face-to-face, systematic and scheduled encouragement from study-trained 'peer' interventionists at the facility. Patients assigned to patient-provider receive face-to-face, systematic and scheduled encouragement provided by study-trained 'provider' interventionists also at the facility. The primary outcomes of change in exercise behavior will be documented by self-reported physical activity and confirmed by fitness testing at baseline, 6, 12 and 24 months during the 1 year of active intervention and 1 year of relapse prevention follow-up. Intervention conditions will be compared on psychosocial mediators including motivational appraisals, ratings of social support, rapport, problem solving and self-efficacy for overcoming barriers to increased physical activity. Novel aspects of this intervention include: (1) delivery of socially based physical activity interventions to an economically disadvantaged urban population, (2) reduction of environmental barriers to be physically active and (3) emphasis on social interactions influencing health habit change. Results of this study have the potential to identify mechanisms of behavior change that could be adopted by physical activity interventions aimed at reducing sedentary behavior and health disparities in high-risk, underserved populations.

Exercise↗
PubMed2002

Risk factors for male breast cancer in Canada, 1994-1998.

Relatively little attention has been paid to the aetiology of male breast cancer and the current understanding of female breast cancer, primarily related to reproductive events, cannot be readily transferred to understanding the cancer in males. However, since male breast cancer occurs in the absence of factors related to childbearing and menstruation, its aetiology may provide special insights into the causes of breast cancer in women. We examined lifestyle risk factors for male breast cancer as part of a Canadian, multi-site, population-based, case-control study. Eighty-one newly diagnosed, histologically confirmed cases and 1905 male controls aged 42-74 were analysed using unconditional logistic regression. Increased risks were found for men with a mother or sister with breast cancer (adjusted odds ratio (OR) 3.65, 95% confidence interval (95% CI) 1.62-8.19). Higher physical activity levels (moderate, and strenuous recreational plus occupational) were associated with a decreased risk of male breast cancer (highest quartile, adjusted OR 0.48, 95% CI 0.26-0.91). Similarly, higher risks were associated with higher weight 2 years before interview (2.19, 95% CI 1.08-4.43), maximum weight (OR 2.66) and higher body mass index (OR 1.60). Higher vegetable consumption and coffee consumption were associated with decreased risk, whereas higher beta-carotene, vitamin E and calcium supplementation were associated with statistically significant increased risk. The small number of cases and multiple comparisons preclude strong conclusions, but our study is consistent with studies suggesting obesity and family history increase risk, and physical activity decreases risk of breast cancer.

Adult↗
PubMed2001

Physical activity, anthropometric factors and risk of pancreatic cancer: results from the Canadian enhanced cancer surveillance system.

To explore the hypothesis that insulin resistance may be an etiologic factor in pancreatic cancer, we assessed the pancreatic cancer risk associated with anthropometric factors and physical activity, both of which are important determinants of insulin sensitivity in humans. Three hundred and twelve patients with histologically confirmed pancreatic cancer were compared to 2,919 controls in a population-based, case-control study in 7 of the 10 Canadian provinces. Participants were asked to report their exposure status for the period 2 years before interview. Men in the highest quartile of body mass index (BMI, > or =28.3 kg/m(2)) were at increased risk of pancreatic cancer [adjusted odds ratio (OR) = 1.90, 95% confidence interval (CI) 1.08-3.35]. In addition, men who reported a decrease in weight of at least 2.9% from their lifetime maximum were at reduced risk compared to those reporting a < or =2.9% loss (> or =10.2% loss, OR = 0.51, 95% CI 0.30-0.86). BMI 2 years before interview was not associated with pancreatic cancer risk among women, though those reporting a > or =12.5% decrease in weight from their lifetime maximum had substantially lower risk compared to those in the baseline quartile (OR = 0.53, 95% CI 0.29-0.99). After adjustment for age, province of residence, dietary intake and anthropometric factors, men in the highest quartile of the composite moderate and strenuous physical activity index were at reduced risk of pancreatic cancer (OR = 0.53, 95% CI 0.31-0.90). Physical activity did not appear to be associated with pancreatic cancer among women, though a tendency for reduced risk with increasing levels of strenuous activity was suggested (p for trend = 0.06). Our findings support the hypothesis that insulin resistance is an etiologic factor in the development of pancreatic neoplasms among men and possibly women.

Age Factors↗
PubMed2001

Lifetime residential and workplace exposure to environmental tobacco smoke and lung cancer in never-smoking women, Canada 1994-97.

Although the risk of lung cancer among never-smokers living with a spouse who smokes has been extensively studied, the impact of lifetime residential and workplace environmental tobacco smoke has received less attention. As part of a large population-based case-control study of lung cancer, we collected lifetime residential and occupational passive smoking information from 71 women with lung cancer and 761 healthy control subjects, all of whom reported being lifetime nonsmokers. The adjusted odds ratio (OR) for lung cancer associated with residential passive exposure only was 1.21 (95% confidence interval [CI] 0.5-2.8). Although more years of and more intense residential passive smoke exposure tended to be associated with higher risk estimates, no clear dose-response relationship was evident. The OR for women with passive exposure as a child and as an adult was 1.63 (95% CI 0.8-3.5) and for those only exposed as an adult 1.20 (95%CI 0.5-3.0). Exposure to environmental tobacco smoke only in the workplace was associated with an adjusted OR of 1.27 (95% CI 0.4-4.0). Risks associated with increasing occupational exposure year tertiles were 1.24, 1.71 and 1.71. Total smoker-years of residential and occupational exposure combined resulted in a statistically significant trend (linear test for trend p = 0.05) with ORs for tertiles of exposure of 0.83, 1.54 and 1.82. Our results are consistent with the literature suggesting that long-term, regular exposure to either residential or occupational environmental tobacco smoke is associated with increased lung cancer risk in never-smoking women.

Adult↗
PubMed2001

Smoking cessation in pregnant women.

Cigarette smoking is considered the most significant modifiable cause of adverse pregnancy outcomes in US women. Smoking cessation in pregnant patients is one of the most effective ways to reduce negative pregnancy outcomes of fetal growth retardation, preterm delivery, and perinatal mortality. Research evidence documenting the effectiveness of health care provider interventions in smoking cessation has led to the PHS recommendation to screen and counsel every patient. Materials from the PHS and NCI are available to assist health care providers in developing a brief office-based intervention. Patient materials for distribution are also available. Increased use of office-based cessation strategies, of cessation programs in community-based interventions, and of pharmacologic therapies is necessary to remedy the public health burden of fetal exposure to tobacco. Relapse prevention methods using office-based and social support systems are important to improve long-term maintenance of cessation in women who quit smoking during pregnancy.

Female↗
PubMed2001

Risk factors for kidney stones in older women in the southern United States.

BACKGROUND: The occurrence of kidney stones is disproportionate in the southern region of the United States. Risk factors for the occurrence of kidney stones in this geographic area have not been reported previously. METHODS: The Women's Health Initiative (WHI) is an ongoing multicenter clinical investigation of strategies for the prevention of common causes of morbidity and mortality among postmenopausal women. A case-control ancillary study was conducted on 27,410 (white or black) women enrolled in the 9 southern WHI clinical centers. There were 1,179 cases (4.3%) of kidney stones at the baseline evaluation. Risk factors for stone formation were assessed in cases versus age- and race-matched control subjects. RESULTS: Risk factors (univariate) included low dietary potassium (2,404 versus 2,500 mg/day, P = 0.006), magnesium (243 versus 253 mg/day, P = 0.003) and oxalate (330 versus 345 mg/day, P = 0.02) intake, as well as increased body mass index (28.5 versus 27.7 kg/m2, P = 0.001) and a history of hypertension (42% versus 34%, P = 0.001). A slightly lower dietary calcium intake (683 versus 711 mg/day, P = 0.04) was noted in case subjects versus control subjects, but interpretation was confounded by the study of prevalent rather than incident cases. Supplemental calcium intake >500 mg/day was inversely associated with stone occurrence. CONCLUSION: Multivariate risk factors for the occurrence of kidney stones in postmenopausal women include a history of hypertension, a low dietary intake of magnesium, and low use of calcium supplements.

Age Factors↗
PubMed2000

Effects on subject response of information brochures and small cash incentives in a mail-based case-control study.

PURPOSE: To investigate the impact on subject response of an information brochure and cash incentives included with mailed questionnaires in case-control studies. METHODS: A randomized trial was carried out within a case-control study investigating cancer in the Province of Ontario. Brochures were included with half of the mailed questionnaires sent to 7487 cases and 2561 controls. Controls were also sent cash incentives of $2, $5, or no money. RESULTS: With the brochure, response changed from 75.0% to 75.8% in cases, and from 70.3% to 71.1% in controls. Adjusting for differences in age, residence, sex, and cancer site/status, the change was 0.2% [95% confidence interval (CI) = -1.7-2.1] in cases, and 0.6% (95% CI = -3.1-4.3) in controls. The $2 and $5 incentives increased overall response in controls from 61.9% to 72.8% and 77.2%, respectively, i.e., by 10.9% (95% CI = 6.1-15.6) and 15.1% (95% CI = 10.4-19.7), after adjustment. This effect was largely confined to urban areas (for $2 and $5, respectively: 5.5% and 14.2% in Toronto, 15.3% and 20.4% in other urban areas vs. 2.7% and 1.0% in rural areas; p = 0.02). Response time showed little or no improvement when the brochure was included, but was markedly reduced for both the $2 and $5 incentives. CONCLUSIONS: Cash incentives can improve subject response in epidemiologic studies, whereas information brochures do not appear to have an effect.

Adult↗
PubMed2000

Passive and active smoking and breast cancer risk in Canada, 1994-97.

BACKGROUND: Studies comparing ever smokers with never smokers have found little increase in breast cancer risk. However, the five published studies examining passive smoking and breast cancer have all suggested associations with both passive and active smoking, particularly premenopausal risk. METHODS: We analyzed data collected through the Canadian National Enhanced Cancer Surveillance System, from 805 premenopausal and 1512 postmenopausal women with newly diagnosed (incident), histologically confirmed, primary breast cancer and 2438 population controls. The mailed questionnaire included questions on breast cancer risk factors and a lifetime residential and occupational history of exposure to passive smoking. RESULTS: Among premenopausal women who were never active smokers, regular exposure to passive smoke was associated with an adjusted breast cancer odds ratio (OR) of 2.3 (95% confidence interval [CI] 1.2-4.6). Passive exposure showed a strong dose-response trend (test for trend p = 0.0007) with an OR of 2.9 (95% CI 1.3-6.6) for more than 35 years of passive residential and/or occupational exposure. When premenopausal women who had ever actively smoked were compared with women never regularly exposed to passive or active smoke, the adjusted OR for breast cancer was also 2.3 (95% CI 1.2-4.5). Among postmenopausal women who were never-active smokers, regular exposure to passive smoke was associated with an adjusted breast cancer OR of 1.2 (95% CI 0.8-1.8) and an OR of 1.4 (95% CI 0.9-2.3) for the most highly exposed quartile of women. The adjusted OR for postmenopausal breast cancer risk for ever-active smokers compared with women never regularly exposed to passive or active smoke was 1.5 (95% CI 1.0-2.3). Statistically significant dose-response relationships were observed with increasing years of smoking, increasing pack-years and decreasing years since quitting. Women with 35 or more years of smoking had an adjusted OR of 1.7 (95% CI 1.1-2.7). CONCLUSIONS: Active and passive smoking may be associated with increased breast cancer risk, particularly premenopausal risk.

Adult↗
PubMed2000

Alcohol, tobacco and coffee consumption and the risk of pancreatic cancer: results from the Canadian Enhanced Surveillance System case-control project. Canadian Cancer Registries Epidemiology Research Group.

The relationship between alcohol, tobacco and coffee consumption and pancreatic cancer was investigated using population-based case-control data obtained from eight Canadian provinces. Our findings are based on analyses performed on 583 histologically confirmed pancreatic cancer cases and 4813 controls. Questionnaire data were obtained directly from 76% of the cases. Male subjects with 35 or more cigarette pack-years had an increased risk of developing pancreatic cancer relative to never smokers (OR= 1.46, 95% CI 1.00-2.14). Similarly, women reporting at least 23 cigarette pack-years of smoking had an odds ratio of 1.84 (95% CI 1.25-2.69). For the most part, consumption of total alcohol, wine, liquor and beer was not associated with pancreatic cancer. Coffee drinking was not related to pancreatic cancer. More work is needed to clarify the role of these and other potentially modifiable risk factors as a means to reduce the incidence of this disease for which treatment results remain disappointing.

Adult↗
PubMed2000

Do sweat calcium losses affect bone mass during firefighter training?

Although participation in vigorous exercise is associated with increased bone mass, recent evidence suggests that loss of calcium in sweat may result in a negative calcium balance and, ultimately, a decrease in bone mass. Anthropometric characteristics, habitual physical activity levels, dietary calcium intake, bone mineral content, and bone turnover markers were measured in 42 male recruits before and after 4 months of firefighter training. During two strenuous mid-training sessions, sweat calcium concentrations were measured; they averaged 1.1 mM. Whole body and total hip bone mineral content increased significantly, as did one marker of bone formation, and were not associated with sweat calcium concentration. This study demonstrates that intense physical training sessions that produce high sweat rates do not have an adverse effect on the bone mineral content of healthy young men.

Absorptiometry, Photon↗
PubMed2000

Glycemic control of older adults with type 2 diabetes: findings from the Third National Health and Nutrition Examination Survey, 1988-1994.

BACKGROUND: Although nearly half of all people who have diabetes are aged 65 or older, glycemic control of older adults with diabetes has not been well described. METHODS: We conducted a cross-sectional study of 1,482 participants with self-reported type 2 diabetes in the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III), a nationally representative sample of the US noninstitutionalized civilian population. Variables included in this analysis included age, sociodemographic factors, drug treatment, and level of glycemic control. RESULTS: The mean % (+/-SE) HbA1c was 7.78 +/- 0.21, 7.64 +/- 0.18, 7.71 +/- 0.14, and 7.27 +/- 0.14 in persons aged 20 to 54, 55 to 64, 65 to 74 and > or = 75 years, respectively. The mean mg/dL (+/-SE) fasting plasma glucose (FPG) was 175.9 +/- 7.6, 164.5 +/- 6.1, 183.3 +/- 5.3, and 158.5 +/- 5.5 in the four age groups and older, respectively. When controlling for race, gender, education, and duration of diabetes, age was not significantly associated with levels of HbA1c [P (trend) =0.17] or FPG [P (trend) =0.19]. Among NHANES III participants aged 65 or older, ADA guidelines for glycemic control (HbA1c < 7%) were achieved by 71%, 44%, and 27% of persons using no drug therapy, oral hypoglycemic agents, and insulin, respectively. CONCLUSIONS: Although many older adults with type 2 diabetes do not achieve targets for glucose control, there is no evidence to suggest that community-dwelling older adults with diabetes are treated less vigorously than younger persons with diabetes.

Age Factors↗