1. Sex difference in high density lipoprotein cholesterol in six countries

CE Davis, DH Williams, RG Oganov, S-C Tao, SL Rywik, Y Stein, JA Little
Am J Epidemiol 1996;143(11):1100-6

It is known that women have higher levels of high density lipoprotein (HDL) cholesterol than men. The authors examined the association between HDL cholesterol and biologic sex in 8,631 women and 10,690 men aged 45-54 years from six countries studied between 1972 and 1989. The variation in the sex difference for HDL cholesterol was significant; the smallest difference (0.06 mmol/liter) was seen in China and the largest (0.40 mmol/liter) in Canada. Adjustment for differences in body mass index, smoking, alcohol use, and heart rate reduced but did not eliminate the variability. The sex difference in HDL cholesterol levels, usually assumed to be due to biologic factors, differs across cultures and may be related to environmental factors.

2. Physical activity and cardiovascular risk factors among elderly men in Finland, Italy, and The Netherlands

Fransje CH Bijnen, Edith JM Feskens, Carl J Caspersen, Simona Giampaoli, Aulikki M Nissinen, Alessandro Menotti, Willem L Mosterd, Daan Kromhout
Am J Epidemiol 1996;143(6):553-61

Physical activity pattern and its relation with cardiovascular risk factors was investigated in 1,402 men aged 69-90 years who participated in the 30-year follow-up survey of the Finnish (Eastern and Western Finland), Italian (Montegiorgio and Crevalcore), and Dutch (Zutphen) cohorts of the Seven Countries Study. Physical activity was assessed with a validated self-administered questionnaire designed for retired men. Total physical activity varied largely within cohorts. Median total reported physical activity ranged from 50 minutes/day in Montegiorgio to 89 minutes/day in Crevalcore. Walking, gardening, and bicycling together contributed more than 70% of total physical activity in all cohorts. Depending on the definition of physical inactivity, the estimated prevalence of inactivity varied between 5% and 33% in Zutphen and between 18% and 68% in Montegiorgio. Total physical activity was inversely associated with resting heart rate (r = -0.11, p < 0.001) and was positively associated with high density lipoprotein (HDL) cholesterol (r = 0.08, p < 0.01) in pooled data. These associations remained statistically significant after adjustment for age, cohort, smoking, body mass index, and alcohol intake. Total activity was not associated with total cholesterol, non-HDL cholesterol, blood pressure, or body mass index. The authors conclude that physical activity may have a beneficial effect on HDL cholesterol levels in elderly men. Walking, gardening, and bicycling contribute substantially to their physical activity pattern.

3. Sex and time trends in cardiovascular disease incidence and mortality: the Framingham Heart Study, 1950-1989

Pamela A Sytkowski, Ralph B D'Agostino, Albert Belanger, William B Kannel
Am J Epidemiol 1996;143(4):338-50

Variations in cardiovascular disease mortality between sexes, over time, and across regions point to population differences in the biologic, behavioral, and environmental factors influencing cardiovascular health. The authors examined 20-year trends in risk factors, incidence, and mortality among women and men in Framingham, Massachusetts, who were members of the Framingham Heart Study and aged 50-59 years in 1950, 1960, and 1970. The incidence declined 21% between the female cohorts (p < 0.01 for trend) with the greatest decline occurring between the 1950 and 1960 cohorts. The 20-year incidence declined only 6% between the male cohorts despite an 18% decline (p < 0.05 for trend) during the first 10 years of follow-up. Cardiovascular disease mortality declined 59% between the female cohorts and 53% between the male cohorts (both p < 0.001 for trend). The largest mortality declines occurred between the 1950 and 1960 female cohorts during the second 10 years of follow-up and between the 1960 and 1970 male cohorts during both follow-up periods. Obesity, hypercholesterolemia, and high blood pressure were significantly lower at baseline and 10 years later in the 1970 female cohort compared with the 1950 cohort (all p < 0.001). Smoking and high blood pressure were significantly lower at baseline and 10 years later in the 1970 male cohort compared with the 1950 cohort (both p < 0.001). More than half of the 51% decline in coronary heart disease mortality observed in women between 1950 and 1989 and one third to one half of the 44% decline observed in men could be attributed to improvements in risk factors in the 1970 cohorts.

4. Socioeconomic inequalities in coronary heart disease and stroke mortality among Australian men, 1979-1993

Stan Bennett
Int J Epidemiol 1996;25(2):266-75

Background. During the 1970s in Australia, mortality from coronary heart disease (CHD) and stroke was higher among lower socioeconomic groups and inequalities were widening. This analysis examines subsequent trends in socioeconomic inequalities, with reference to socioeconomic patterns in major cardiovascular risk factors.

Methods. Socioeconomic status was defined by occupation. Age-standardized mortality rates were calculated for men aged 25-64, using death registration data and labour force estimates for 1979-1993. Risk factor data were taken from three cross-sectional population surveys conducted in 1980, 1983 and 1989.

Results. Men in manual occupations were at least 35% more likely to die from CHD than men in professional occupations, and 60% more likely to die from stroke. Their 5-year population risk of a coronary event was 30% higher. Since 1979, both groups experienced reductions in coronary risk and mortality.

Conclusions. Socioeconomic inequalities in CHD mortality continued to widen during the early 1980s, stabilized thereafter and persisted into the 1990s. Decreases in blood pressure and smoking prevalence contributed most to declines in coronary risk and to socioeconomic differentials.

5. Protein consumption and bone fractures in women

Diane Feskanich, Walter C Willett, Meir J Stampfer, Graham A Colditz
Am J Epidemiol 1996;143(5):472-9

Dietary protein increases urinary calcium losses and has been associated with higher rates of hip fracture in cross-cultural studies. However, the relation between protein and risk of osteoporotic bone fractures among individuals has not been examined in detail. In this prospective study, usual dietary intake was measured in 1980 in a cohort of 85,900 women, aged 35-59 years, who were participants in the Nurses' Health Study. A mailed food frequency questionnaire was used and incident hip (n = 234) and distal forearm (n = 1,628) fractures were identified by self-report during the following 12 years. Information on other factors related to osteoporosis, including obesity, use of postmenopausal estrogen, smoking, and physical activity, was collected on biennial questionnaires. Dietary measures were updated in 1984 and 1986. Protein was associated with an increased risk of forearm fracture (relative risk (RR) = 1.22, 95% confidence interval (CI) 1.04-1.43, p for trend = 0.01) for women who consumed more than 95 g per day compared with those who consumed less than 68 g per day. A similar increase in risk was observed for animal protein, but no association was found for consumption of vegetable protein. Women who consumed five or more servings of red meat per week also had a significantly increased risk of forearm fracture (RR = 1.23, 95% CI 1.01-1.50) compared with women who ate red meat less than once per week. Recall of teenage diet did not reveal any increased risk of forearm fracture for women with higher consumption of animal protein or red meat during this earlier period of life. No association was observed between adult protein intake and the incidence of hip fractures, though power to assess this association was low.

6. Silica and aluminum in drinking water and cognitive impairment in the elderly

Hélène Jacqmin-Gadda, Daniel Commenges, Luc Letenneur, Jean-François Dartigues
Epidemiology 1996;7:281-5

We studied the relation between silica and aluminum levels in drinking water and the risk of cognitive impairment using data from a population-based survey of 3,777 French subjects age 65 years and older. We also studied the effect of pH and the concentrations of calcium, magnesium, fluorine, zinc, copper, and iron. We used a mixed effects logistic regression adjusting for age, sex, educational level, and occupation of the subjects. We confirmed the inverse relation previously found between calcium level and cognitive impairment. We found no important association between cognitive impairment and fluorine, magnesium, iron, copper, or zinc. The association between cognitive impairment and aluminum depended on the pH and the concentration of silica: high levels of aluminum appeared to have a deleterious effect when the silica concentration was low, but there was a protective effect when the pH and the silica level were high. The threshold for an aluminum effect, however, was very low (3.5 µg per liter) and did not support the hypothesis of a deleterious effect for only high levels of aluminum.

7. Aspirin use and cognitive function in the elderly

Til Stürmer, Robert J Glynn, Terry S Field, James O Taylor, Charles H Hennekens
Am J Epidemiol 1996;143(7):683-91

Decline in cognitive function in the elderly is common and represents a major clinical and public health concern. Aspirin may reduce the decline in cognitive function by influencing multi-infarct dementia, but data are sparse. The East Boston Senior Health Project is a population-based cohort study that enrolled 3,809 community-dwelling residents aged 65 years and older in 1982-1983 and followed them with home visits every 3 years until 1988-1989. Trained interviewers assessed cognitive function by using the Short Portable Mental Status Questionnaire and assessed medication use, including over-the-counter drugs. Response to the Short Portable Mental Status Questionnaire was scored as high, medium, or low, and decline was defined as transition to a lower category. Participants who used drugs containing aspirin in the 2 weeks prior to the interview were classified as aspirin users. Multiple logistic regression was used to obtain adjusted odds ratios and their 95% confidence intervals for decline of cognitive function. The estimating equation approach was used to adjust the standard errors for repeated measurements. Aspirin users had an odds ratio for cognitive decline of 0.97 (95% confidence interval 0.82-1.15). Low frequency of aspirin use (less than daily) was associated with an odds ratio of 0.87 (95% confidence interval 0.69-1.09). Although no substantial effect was observed, the data are also compatible with a modest benefit of aspirin, especially with intermittent use, on decline of cognitive function. Concern about small residual biases from self-selection or confounding suggests that randomized trials will be necessary to provide definitive data on this question.

8. Income class and pharmaceutical expenditure in Canada: 1964-1990

Joel Lexchin
Can J Public Health 1996;87(1):46-50

In the 1970s, nearly all Canadian provinces introduced drug programs to subsidize purchases by low-income families. This study was undertaken to determine whether these programs were successful in reducing out-of-pocket pharmaceutical expenditures for low-income families and individuals, and to compare expenditures in this group with those of high-income families. Expenditures were calculated for a low- and a high-income group from Statistics Canada surveys conducted between 1964 and 1990. In the low-income group there was a 40% decline in drug expenditure measured as a percentage of total family expenditure and this was coincident with the introduction of provincial drug programs. However, the high-income group had an even larger decrease in drug expenditure. Per capita spending as a percentage of total family expenditure in the low-income group, was seven times that of the high-income group and there was no change in this ratio after the introduction of the drug plans.

9. A survey of population-based drug databases in Canada

Elizabeth Miller, Brian Blatman, Thomas R Einarson
Can Med Assoc J 1996;154(12):1855-64

Objective: To identify the population-based drug databases in Canada and to determine their comprehensiveness and accessibility for performing pharmacoepidemiologic and outcomes research.

Design: Survey (four-part mailed questionnaire).

Setting: Public and private third-party drug plans across Canada.

Participants: All provincial and territorial drug plan or pharmacare managers as well as selected private plan managers including health benefit consultants, group insurers and claims adjudicators/pharmacy benefit managers (CA/PBMs).

Outcome measures: Patient, drug and pharmacy information; potential for electronic linkages to other provincial databases (e.g., physician, hospital, vital statistics); accessibility of information; population profile.

Results: Of the 32 recipients of the questionnaire 29 (91%) responded and 18 (56%) completed the survey. Most databases were reported to contain patient information (e.g., patient identification number, age, sex and medication history) and prescription drug information (e.g., drug identification number, strength, quantity and cost). Six provinces and one territory reported the capability to link to other databases (e.g., hospital and physician databases). One CA/PBM reported some links to selected long-term disability data. All of the government databases except those in British Columbia and the Yukon Territory allowed use of the data for research purposes. Manitoba and Saskatchewan included all residents of the province in their database; the others included selected groups (e.g., residents 65 years of age or older, people on social assistance or people covered by private group insurance).

Conclusion: A number of public and private population-based databases are available for use in pharmacoepidemiologic and outcomes research.

10. Direct and indirect costs of asthma in Canada, 1990

Murray D Krahn, Catherine Berka, Peter Langlois, Allan S Detsky
Can Med Assoc J 1996;154(6):821-31

Objective: To calculate the direct and indirect costs of asthma in Canada.

Design: Cost-of-illness study.

Setting: Canada.

Patients: All Canadians receiving inpatient or outpatient care for asthma in 1990.

Outcome measures: Direct costs incurred by inpatient care, emergency services, physician and nursing services, ambulance use, drugs and devices, outpatient diagnostic tests, research and education. Indirect costs from productivity loss due to absence from work, inability to perform housekeeping activities, need to care for children with asthma who were absent from school, time spent travelling and waiting for medical care, and premature death from asthma. All costs are in 1990 Canadian dollars.

Results: Depending on assumptions, the total cost of asthma was estimated to be between $504 million and $648 million. Direct costs were $306 million. The single largest component of direct costs was the cost of drugs ($124 million). The largest component of indirect costs was illness-related disability ($76 million).

Conclusions: Annual costs of treating asthma are comparable to the individual cost of infectious diseases, hematologic diseases, congenital defects, perinatal illnesses, home care and ambulance services. Asthma costs may increase in the future, given current morbidity and mortality trends. Further evaluation of the effectiveness and cost-effectiveness of available asthma interventions in addition to aggregate cost data are required to determine whether resource allocation for the treatment of asthma can be improved.

11. Cancer incidence and mortality trends in Northeastern Ontario

Nancy E Lightfoot, Gordon M Fehringer, Randy J Bissett, D Claire McChesney, Jason J White
Can J Public Health 1996;87(1):17-24

Over 629,000 people reside in the catchment area for the Northeastern Ontario Regional Cancer Centre. Historically, the area was renowned for employment in mining, forestry and lumbering, agriculture, the railway, and pulp and paper. At present, it is known for mining; community, business, and personal services; trade; manufacturing; and construction. Comparison of cancer incidence and mortality trends for two decades (1971-1980 and 1981-1990) with those of Ontario has revealed statistically significant excesses, at the 5% level or better, of trachea, bronchus, and lung cancer cases (SIR = 123 for 1971-1980 and 125 for 1981-1990) and deaths in men (SMR = 116 and 125, respectively); for women, excesses were observed for trachea, bronchus and lung cancer cases (SIR = 114 and 118), and cervical cancer cases (SIR = 142 and 115) and deaths (SMR = 133 and 128). Enhanced recruitment strategies and early educational interventions are identified as priorities.

12. Occupational risk factors for prostate cancer: results from a case-control study in Montréal, Québec, Canada

Kristan J Aronson, Jack Siemiatycki, Ronald Dewar, Michel Gérin
Am J Epidemiol 1996;143(4):363-73

A population-based case-control study of cancer and occupation was carried out in Montréal, Canada. Between 1979 and 1986, 449 pathologically confirmed cases of prostate cancer were interviewed, as well as 1,550 cancer controls and 533 population controls. Job histories were evaluated by a team of chemist/hygienists using a checklist of 294 workplace chemicals. After preliminary evaluation, 17 occupations, 11 industries, and 27 substances were selected for multivariate logistic regression analyses to estimate the odds ratio between each occupational circumstance and prostate cancer with control for potential confounders. There was moderate support for risk due to the following occupations: electrical power workers, water transport workers, aircraft fabricators, metal product fabricators, structural metal erectors, and railway transport workers. The following substances exhibited moderately strong associations: metallic dust, liquid fuel combustion products, lubricating oils and greases, and polyaromatic hydrocarbons from coal. While the population attributable risk, estimated at between 12% and 21% for these occupational exposures, may be an overestimate due to our method of analysis, even if the true attributable fraction were in the range of 5-10%, this represents an important public health issue.

13. Cervical cancer screening: are the 1989 recommendations still valid?

E Jean Parboosingh, George Anderson, E Aileen Clarke, Suzanne Inhaber, Elizabeth Kaegi, Christina Mills, Yang Mao, Lorie Root, Gavin Stuart, Sylvie Stachenko
Can Med Assoc J 1996;154(12):1847-53

Although screening for cervical cancer has been shown to be effective in reducing the morbidity and mortality associated with this disease, and despite many attempts to encourage the development of provincial programs, as of 1995 no province had a comprehensive screening program for cervical cancer. Participants at the Interchange '95 workshop, held in Ottawa in November 1995, reviewed the recommendations of the 1989 National Workshop on Screening for Cancer of the Cervix and identified factors that have impeded their implementation. Participants discussed the need for comprehensive information systems, quality control and strategies to increase recruitment of unscreened and underscreened women. They concluded that the formation of a Cervical Cancer Prevention Network involving key stakeholders will facilitate the development and implementation of provincial programs to ensure optimal screening. They agreed that, in the interim, recommendations for practising physicians should remain as they were following the 1989 workshop.

14. Dietary assessment in epidemiology: comparison of a food frequency and a diet history questionnaire with a 7-day food record

Meera Jain, Geoffrey R Howe, Thomas Rohan
Am J Epidemiol 1996;143(9):953-60

The validity of two types of diet assessment methods, a self-administered food frequency questionnaire and an interviewer-administered detailed diet history, was assessed relative to a 7-day food record on a population-based sample of 95 men and 108 women in Toronto, Canada, between May 1989 and July 1990. Each study subject completed both questionnaire methods, a food frequency questionnaire and an interviewer administered diet history, as well as a 7-day food record in a crossover design. Data were analyzed for both unadjusted and energy-adjusted nutrients to estimate Pearson's and intraclass correlations and agreement within categories. Mean values for the intake of most nutrients assessed by the two questionnaire methods were similar. Average, energy-adjusted Pearson's correlation coefficients for men between a food frequency questionnaire and a 7-day food record were 0.55 for macronutrients and 0.48 for micronutrients compared with 0.47 for macro- and 0.48 for micronutrients between an interviewer-administered diet history and a 7-day food record. For women, they were 0.48 for macro-and 0.54 for micronutrients between a food frequency questionnaire and a 7-day food record and 0.46 and 0.49, respectively, between an interviewer-administered diet history and a 7-day food record. The energy-adjusted Pearson correlations were generally higher than were the energy-unadjusted Pearson correlations and the intraclass correlations. The present study suggests that a food frequency questionnaire is comparable with an interviewer-administered diet history as a predictor of nutrients as estimated from a 7-day food record.

15. Determinants of mortality from cystic fibrosis in Canada, 1970-1989

Mary Corey, Vernon Farewell
Am J Epidemiol 1996;143(10):1007-17

The frequency, prevalence, and mortality patterns of cystic fibrosis were analyzed in 3,795 patients documented in the Canadian Patient Data Registry in 1970-1989. Cystic fibrosis frequency in the 1970-1979 birth cohort was virtually identical to the commonly quoted 1 in 2,500. In 1985-1989, median survival age was 36.7 years for males and 27.8 years for females, compared with 26.6 and 19.7, respectively, in 1970-1974. However, there were significant regional differences when Canada was divided into the four regions, East, Quebec, Ontario, and West. In Quebec, patients were younger at diagnosis and until recently had greater mortality than patients in other regions, which suggests more severe disease; dramatically improved survival in the 1980s coincided with a change from a restricted fat diet to a high fat diet. Improved survival in Ontario in the 1970s accompanied this change in dietary therapy, which may also account for good survival throughout the study period in the East. The West showed gradually improving survival, similar to that reported in other parts of the world. Proportional hazards analysis showed pulmonary function to be the best predictor of survival. Poorer survival in females was associated with poorer weight, but the interrelation of declining pulmonary function, weight maintenance, sex, and mortality requires further study. The effect of pulmonary colonization with Pseudomonas aeruginosa was confounded with degree of pulmonary dysfunction, but colonization with Burkholderia cepacia (previously Pseudomonas cepacia) was associated with increased mortality at all levels of pulmonary function.

16. Influence of gender on susceptibility to multiple sclerosis and age of onset in concordant sibships

Sharon A Warren, KG Warren
Int J Epidemiol 1996;25(1):142-5

Background. Research has produced conflicting findings about whether there is an excess of like-sexed pairs among concordant multiple sclerosis (MS) sibships. Although a positive correlation in onset age among sibling pairs overall has been reported, no data have been published describing age at onset correlations for like-sexed versus unlike-sexed pairs. The purpose of this study was to provide additional information on both issues.

Methods. Patients with an MS sibling were sought through the files of the University of Alberta MS Clinic (Edmonton, Canada). The clinic neurologist either reviewed clinical/autopsy material or assessed relatives of index cases prior to accepting the relative as having MS. Pairs of siblings (excluding twins) were divided into (1) male-male pairs, (2) female-female pairs, and (3) female-male pairs.

Results. A total of 62 concordant sibling pairs were identified. There were 33 like-sexed pairs (6 male-male/27 female-female) and 29 unlike-sexed pairs. The observed number of like-sexed pairs was not significantly different from the expected frequency using 2 x 2 x² analysis, where expected values represent the binomial distribution predicted from the frequency of each sex as determined by total number of males and females. The age at onset intraclass correlation coefficient was -0.09 for sibling pairs overall, -0.22 for like-sexed pairs and +0.02 for unlike-sexed pairs.

Conclusions. This study does not provide evidence for an association between disease susceptibility and gender in siblings concordant for MS; nor does it suggest that genetics plays a role in onset age.

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