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Abstract Reprints 1. Reliability and validity of proxy respondent information about childhood injury: an assessment of a Canadian surveillance system Colin Macarthur, Geoffrey Dougherty, I Barry Pless The reliability and validity of proxy respondent information in the Canadian Hospitals Injury Reporting and Prevention Program surveillance system was assessed. A standardized form was used to collect data on injury date, location, context (activity at the time), breakdown factor (what went wrong), mechanism, product involvement, safety precaution use, and motor vehicle involvement. The test-retest method determined reliability, with the kappa coefficient quantifying agreement between respondent information provided in the emergency department and later during a telephone interview. Of 421 eligible respondents, 325 (77%) completed the telephone interview, with a median time to interview of 33 hours (range 24-70 hours). Agreement was high for all items; kappa coefficients ranged from 0.79 (substantial agreement) to 1.00 (perfect agreement). Reliability was not significantly modified by respondent view of the injury event, age of the child, language of the form, or level of respondent education. Validity was determined by measuring the agreement between respondent information and that provided by an independent witness. Witness information was considered to represent the truth. Of the 140 injury events selected, 92 (66%) had the form completed by both the original respondent and an independent witness. Kappa coefficients were greater than 0.65 for all but one item (safety precaution use), and the positive predictive value of respondent information for item categories whose prevalence was ³ 0.25 ranged from 0.82 to 0.95. The authors conclude that proxy respondent data on childhood injury are both reliable and valid. 2. Evaluation of a four-year bicycle helmet promotion campaign in Quebec aimed at children ages 8 to 12: impact on attitudes, norms and behaviours Céline Farley, Joanne Otis, Marie Benoît Objective: This study evaluated a four-year bicycle helmet promotion campaign. Methods: Children's attitudes, social norms, intentions to wear a bicycle helmet as well as helmet ownership were measured. Evaluation was based on a pre-experimental static group comparison design repeated at two (1991) and four years (1993) after implantation, with a non-randomized control group. 3,424 students completed a self-administered questionnaire (experimental: 2,097, control: 1,327). Results: The program had a significant impact on helmet ownership (1989): 4%; 1991: 26%; 1993: 56%). The program was the principal predictor of high intention to use a bicycle helmet. Time was the principal predictor of ownership with exposure to the program being the next predictor. Conclusion: This study showed that time is an important factor in bicycle helmet acquisition, and that a long-term community-based program can accelerate the process of adopting this behaviour. 3. The effect of body mass index and oestrogen receptor level on survival of breast cancer patients Stephen C Newman, Alan W Lees, Heather J Jenkins Background. Epidemiological studies have demonstrated that obesity and low oestrogen receptor level adversely affect survival from breast cancer. Few studies have examined the joint effects of these variables. Methods. A cohort study was conducted in which 1169 breast cancer patients from the Northern Alberta Breast Cancer Registry were followed for an average of 4.4 years. A number of variables related to breast cancer incidence and prognosis were studied. Body mass index (BMI) was used as a proxy measure of obesity. Results. A Cox regression analysis resulted in a final model with terms for size of tumour, number of positive axillary nodes, oestrogen receptor level, BMI, and age at diagnosis, plus an interaction term for node status and BMI. Having relatively less oestrogen receptor increased the hazard ratio by 1.8 (95% CI : 1.4-2.3); for women with no positive nodes, being in the highest quartile of BMI increased the hazard ratio by 2.5 (95%. CI : 1.2-5.2) compared to the lowest quartile. Conclusions. BMI and oestrogen receptor level independently influence survival from breast cancer, but BMI affects survival only in patients with no positive axillary nodes. 4. Cross-cultural measurements of psychological well-being: the psychometric equivalence of Cantonese, Vietnamese, and Laotian translations of the Affect Balance Scale Gerald M Devins, Morton Beiser, Rene Dion, Luc G Pelletier,
R Gary Edwards Objectives. This paper evaluates the cultural equivalence of Cantonese, Vietnamese, and Laotian translations of the Affect Balance Scale. Methods. The scale was completed by 399 Vietnamese, 193 Laotian, 756 Cantonese, and 319 English speakers who were participants in the Clarke Institute-University of Toronto Refugee Resettlement Project (n = 1667). Results. Confirmatory factor analyses indicated a good fit between the hypothesized two-factor model (separate factors for positive and negative affect) across the original English-language version and each of the Asian-language translations. Factorial invariance (numbers and patterns of factor loadings) was evident across all versions of the scale. No evidence of item bias was detected by mixed Language X Item analyses of variance. Acceptable reliability was observed; coefficient alphas ranged from .62 to .72 for positive affect and from .62 to .70 for negative affect items. Conclusions. These findings substantiate the cultural equivalence of the three translations of the scale for population health research. Important future research directions made possible by the availability of culturally equivalent instruments are discussed. 5. Adjusted odds ratios for case-control studies with missing confounder data in controls Samy Suissa, Michael D deB Edwardes Nonexperimental studies using computerized databases often give rise to missing or partially available information on confounders. A frequent situation occurs when data on exposure are available for all subjects of a case-control study, but data on confounders are available only for the cases but not for the controls. In that situation, the fact of confounding can be verified by assessing the association between exposure and a confounder in the cases, but the data are insufficient to produce an adjusted estimate of the relative risk if confounding is found to be present. We propose simple conditions under which an adjusted estimate of the relative risk can be obtained when data on a confounder are available only for the cases, and we derive formulae for the estimator and its confidence limits. The method requires an external estimate of the confounder prevalence or, additionally, of the confounder-exposure odds ratio. We illustrate the technique with data from a nested case-control study of the risk of acute cardiac death associated with the use of bronchodilator drugs within a cohort of 12,301 asthmatics, with smoking as the confounder of interest. 6. Association of smoking, body mass, and physical activity with risk of prostate cancer in the Iowa 65+ Rural Health Study (United States) James R Cerhan, James C Torner, Charles F Lynch, Linda
M Rubenstein, Jon H Lemke, Michael B Cohen, David M Lubaroff, Robert B
Wallace Smoking, obesity, alcohol, and physical activity can modulate the endocrine system, and therefore have been hypothesized to play a role in the etiology of prostate cancer. At baseline in 1982, 80 percent (n = 3,673) of the noninstitutionalized persons age 65+ in two rural Iowa (United States) counties were enrolled into the Iowa 65+ Rural Health Study. Follow-up for mortality was complete through 1993, and cancer experience was determined by linkage to the State Health Registry of Iowa cancer database for the years 1973-93. We analyzed data on 1,050 men aged 65 to 101 years (mean age 73.5) with a full interview in 1982 and with no documented cancer in the 10 years prior to baseline. Through 1993 (8,474 person-years of follow-up), there were 71 incident cases of prostate cancer. In a multivariate model, age, cigarette smoking (relative risk [RR] = 2.9 for currently smoking 20 or more cigarettes per day compared with never smoking; P trend = 0.009), greater body mass index (BMI) (wt/ht2) (RR = 1.7 for BMI > 27.8 kg/m2 compared with < 23.6; P trend = 0.1), and greater level of physical activity (RR = 1.9 for high activity level cf inactive; P trend = 0.05) were independent predictors of prostate cancer, and these associations were stronger for regional or disseminated disease at diagnosis. Percent change in BMI from age 50 to baseline was associated positively with risk (P trend = 0.01), and this association appeared to be stronger in heavier men. There were no data on diet. These findings suggest that smoking, overweight, and weight gain in later life are risk factors for prostate cancer and support a hormonal etiology; the positive association for physical activity confirms some previous reports, but remains without a credible biologic mechanism. 7. A prospective study of oral contraceptive use and risk of breast cancer (Nurses' Health Study, United States) Susan E Hankinson, Graham A Colditz, JoAnn E Manson,
Walter C Willett, David J Hunter, Meir J Stampfer, Frank E Speizer Results of previous epidemiologic studies have provided reassurance that there is little, if any, increase in risk of breast cancer with oral contraceptive (OC) use in general. However, in several studies, an increased risk of breast cancer has been observed in two subgroups, young women who used OCs for extended durations and in women who used OCs prior to a first-term pregnancy. We evaluated these relationships using data from the ongoing Nurses' Health Study cohort (United States). We documented 3,383 cases of breast cancer from 1976 to 1992 among 1.6 million person-years of follow-up. We observed no overall relationship between duration of OC use and breast cancer risk, even among women who reported using OCs for 10 or more years (multivariate relative risk [RR] = 1.11, 95 percent confidence interval [CI] = 0.94-1.32). Among women less than 45 years of age, the multivariate RR for using OCs for 10 or more years was 1.07 (CI = 0.70-1.65) compared with never-users. The risk associated with five or more years of OC use prior to a first full-term pregnancy compared with never-use was 0.96 (CI = 0.65-1.43). Among women less than 45 years of age, we observed no evidence of an increased risk with OC use before a first full-term pregnancy (use for five or more years: RR = 0.57, CI = 0.24-1.31). Because of the age distribution of our cohort, we were unable to evaluate these relationships among women less than 40 years of age. Our study provides considerable evidence that long-term past OC use, either overall or prior to a first full-term pregnancy, does not result in any appreciable increase in breast cancer risk in women over 40 years of age. 8. Non-dietary factors as risk factors for breast cancer, and as effect modifiers of the association of fat intake and risk of breast cancer David J Hunter, Donna Spiegelman, Hans-Olov Adami, Piet
A van den Brandt, Aaron R Folsom, R Alexandra Goldbohm, Saxon Graham,
Goeffrey R Howe, Lawrence H Kushi, James R Marshall, Anthony B Miller,
Frank E Speizer, Walter Willett, Alicja Wolk, Shiaw-Shyuan Yaun To assess more precisely the relative risks associated with established risk factors for breast cancer, and whether the association between dietary fat and breast cancer risk varies according to levels of these risk factors, we pooled primary data from six prospective studies in North America and Western Europe in which individual estimates of dietary fat intake had been obtained by validated food-frequency questionnaires. Based on information from 322,647 women among whom 4,827 cases occurred during follow-up: the multivariate-adjusted risk of late menarche (age 15 years or more compared with under 12) was 0.72 (95 percent confidence interval [CI] = 0.62-0.82); of being postmenopausal was 0.82 (CI = 0.69-0.97); of high parity (three or more births compared with none) was 0.72 (CI = 0.61-0.86); of late age at first birth (over 30 years of age compared with 20 or under) was 1.46 (CI = 1.22-1.75); of benign breast disease was 1.53 (CI = 1.41-1.65); of maternal history of breast cancer was 1.38 (CI = 1.14-1.67); and history of a sister with breast cancer was 1.47 (CI = 1.27-1.70). Greater duration of schooling (more than high-school graduation compared with less than high-school graduation) was associated significantly with higher risk in age- adjusted analyses, but was attenuated after controlling for other risk factors. Total fat intake (adjusted for energy consumption) was not associated significantly with breast cancer risk in any strata of these non-dietary risk factors. We observed a marginally significant interaction between total fat intake and risk of breast cancer according to history of benign breast disease, with fat intake being associated nonsignificantly positively with risk among women with a previous history of benign breast disease; no other significant interactions were observed. Risks for reproductive factors were similar to those observed in case-control studies; relative risks for family history of breast cancer were lower. We found no clear evidence in any subgroups of a major relation between total energy-adjusted fat intake and breast cancer risk. 9. Risk factor correlates of body mass index Simon W Rabkin, Yue Chen, Lawrence Leiter, Liyan Liu,
Bruce A Reeder, Canadian Heart Health Surveys Research Group Objective: To examine the association of obesity, as reflected by body mass index, with other cardiovascular risk factors specifically blood pressure, smoking, physical inactivity, plasma lipid levels and diabetes mellitus. Design: Population-based, cross-sectional surveys. Setting: Ten Canadian provinces between 1986 and 1992. Participants: A probability sample of 29 855 men and women aged 18 to 74 years was selected from the health insurance registration files of each province and invited to participate. Anthropometry was performed on 19 841 (66%) of these adults. Outcome measures: Body mass index (BMI, kg/m2), systolic and diastolic blood pressure, smoking status, level of leisure-time physical activity, self-reported diabetes, levels of plasma total cholesterol, high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL) and triglycerides (TRIG). Results: The prevalence of high blood pressure increased with increasing BMI. The gradient of increase was steepest for younger (18-34 years) men and women compared with older (55-74 years) groups. The prevalence of physical inactivity in women tended to increase with increasing BMI except in the lowest BMI category. The J-shaped relationship, although weaker, was also seen in men. The prevalence of self-reported diabetes mellitus was greater with higher BMI categories at all ages and for both sexes except for the youngest group of men. The prevalence of dyslipidemia was related to BMI, as LDL and TRIG levels were higher and HDL levels lower in those with higher BMI. BMI was strongly related to blood pressure, diabetes mellitus and lipid abnormalities. Conclusion: These data suggest a central role for obesity in cardiovascular risk and the potential importance of intervention strategies aimed at reducing population obesity in the management of other cardiovascular risk factors. 10. The relationship between dietary fat intake and risk of colorectal cancer: evidence from the combined analysis of 13 case-control studies Geoffrey R Howe, Kristan J Aronson, Enrique Benito,
Roberto Castelleto, Jacqueline Cornée, Stephen Duffy, Richard P Gallagher,
José M Iscovich, Jiao Deng-ao, Rudolf Kaaks, Gabriel A Kune, Susan Kune,
Hin P Lee, Marion Lee, Anthony B Miller, Ruth K Peters, John D Potter,
Elio Riboli, Martha L Slattery, Dimitrios Trichopoulos, Albert Tuyns,
Anastasia Tzonou, Lyndsey F Watson, Alice S Whittemore, Anna H Wu-Williams,
Zheng Shu The objective of this study was to examine the effects of the intake of dietary fat upon colorectal cancer risk in a combined analysis of data from 13 case-control studies previously conducted in populations with differing colorectal cancer rates and dietary practices. Original data records for 5,287 cases of colorectal cancer and 10,470 controls were combined. Logistic regression analysis was used to estimate odds ratios (OR) for intakes of total energy, total fat and its components, and cholesterol. Positive associations with energy intake were observed for 11 of the 13 studies. However, there was little, if any, evidence of any energy-independent effect of either total fat with ORs of 1.00, 0.95, 1.01, 1.02, and 0.92 for quintiles of residuals of total fat intake (P trend = 0.67) or for saturated fat with ORs of 1.00, 1.08, 1.06, 1.21, and 1.06 (P trend = 0.39). The analysis suggests that, among these case-control studies, there is no energy-independent association between dietary fat intake and risk of colorectal cancer. It also suggests that simple substitution of fat by other sources of calories is unlikely to reduce meaningfully the risk of colorectal cancer. 11. Hormone replacement therapy, reproductive history, and colon cancer: a multicenter, case-control study in the United States Ellen Kampman, John D Potter, Martha L Slattery, Bette
J Caan, Sandra Edwards Hormonal factors have been inconsistently associated with colon cancer risk in women. The associations between reproductive events, menstrual factors, exogenous hormones, and colon cancer were evaluated in a large case-control study (894 female cases and 1,120 female age-matched population-based controls) in the United States, stratifying by age at diagnosis, tumor site, family history and other potential risk factors. Overall, higher parity was associated with a marginally decreased risk of colon cancer (five or more births compared with nulliparous: odds ratio [OR] = 0.75, 95 percent confidence interval [CI] = 0.53-1.06) after adjusting for age at diagnosis, family history of colorectal cancer, vigorous lifetime physical activity, body mass index (BMI) (wt/ht1.5), total energy intake, and aspirin use. No important associations were observed for other reproductive or menstrual events. An inverse association between recent use of hormone replacement therapy (HRT) and colon cancer was observed (OR = 0.71, CI = 0.56-0.89). Although interaction terms were not significant, this inverse association appeared to be more pronounced for those with an older age at diagnosis; for those without a first-degree relative with colorectal cancer; and for those with a relatively low BMI. The reduced risk associated with HRT use did not appear to be explained by other behaviors related to HRT use. 12. A prospective study of menopausal hormones and risk of colorectal cancer (United States) Rebecca Troisi, Catherine Schairer, Wong-Ho Chow, Arthur
Schatzkin, Louise A Brinton, Joseph F Fraumeni Jr The relation of colorectal cancer and its subsites with use of menopausal hormones was evaluated in the United States among 40,464 postmenopausal women, 41 to 80 years of age, who initially volunteered for a nationwide breast-cancer screening program and were followed for an average of 7.7 years. Ever-use of menopausal hormones was not associated with risk of total colorectal cancers (relative risk [RR] = 0.99, 95 percent confidence interval [CI] = 0.79-1.2) or cancers of the colon (RR = 1.1, CI = 0.81-1.6) or rectum (RR = 1.1, CI = 0.59-1.9). Recent hormone users, however, had a small nonsignificant reduction in risk of colorectal cancer (RR = 0.78, CI = 0.55-1.1), which was most pronounced for distal colon (RR = 0.68, CI = 0.29-1.6) and rectal tumors (RR = 0.64, CI = 0.24-1.7). No effect was observed for former hormone users, and risk generally did not vary by time since last use, type of regimen, or duration of use. However, the reduced risk for recent users was stronger for users of five or more years duration. These data show some lowering of colorectal cancer risk among recent menopausal hormone users of long duration. 13. Serum dioxin and diabetes mellitus in veterans of Operation Ranch Hand Gary L Henriksen, Norma S Ketchum, Joel E Michalek,
James A Swaby We studied diabetes mellitus and glucose and insulin levels in Air Force veterans exposed to Agent Orange and its contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), during the Vietnam War. The index subjects of the Air Force's ongoing 20-year prospective epidemiologic study are veterans of Operation Ranch Hand (N = 989), the unit responsible for aerial herbicide spraying in Vietnam from 1962 to 1971. Other Air Force veterans who served in Southeast Asia during the same period but were not involved with spraying herbicides serve as Comparisons (N = 1,276). The median serum dioxin level in the Ranch Hand group was 12.2 parts per trillion (ppt) (range = 0-617.8 ppt), and the median dioxin level in the Comparison group was 4.0 ppt (range = 0-10 ppt). We found that glucose abnormalities [relative risk = 1.4; 95% confidence limits (CL) = 1.1, 1.8], diabetes prevalence (relative risk = 1.5; 95% CL = 1.2, 2.0), and the use of oral medications to control diabetes (relative risk = 2.3; 95% CL = 1.3, 3.9) increased, whereas time-to-diabetes-onset decreased with dioxin exposure. Serum insulin abnormalities (relative risk = 3.4; 95% CL = 1.9, 6.1) increased with dioxin exposure in nondiabetics. These results indicate an adverse relation between dioxin exposure and diabetes mellitus, glucose metabolism, and insulin production. 14. Kidney cancer in Canada: the rapidly increasing incidence of adenocarcinoma in adults and seniors Shiliang Liu, Robert Semenciw, Howard Morrison, Dena
Schanzer, Yang Mao Purpose: To examine kidney cancer incidence and mortality patterns since 1969 in Canada. Methods: Linear regression of the log rates was used to estimate secular trends by age group and sex, and age-period-cohort models were fitted to examine changes in kidney cancer and renal adenocarcinoma incidence rates. Results: A substantial increase in incidence rates was observed among those 35 years and older, with average increases of 2.5% or more annually for both sexes. Age-period-cohort modelling suggested that much of this increase resulted from a period effect. Changes in mortality were much more modest, especially among those aged 0-34, for whom mortality rates actually declined by an average of 4.2% and 5.4% annually for males and females respectively. Conclusions: Kidney cancer incidence rates have increased significantly, especially renal adenocarcinoma among adults and seniors. Diagnostic improvements and increasing levels of obesity in the Canadian population may have contributed to these trends. [Previous] [Table of Contents] [Next]
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