Showing papers by "Alicja Wolk published in 1999"

Long-term intake of dietary fiber and decreased risk of coronary heart disease among women.

Abstract: ContextEpidemiological studies of men suggest that dietary fiber intake protects against coronary heart disease (CHD), but data on this association in women are sparse.ObjectiveTo examine the association between long-term intake of total dietary fiber as well as fiber from different sources and risk of CHD in women.Design and SettingThe Nurses' Health Study, a large, prospective cohort study of US women followed up for 10 years from 1984. Dietary data were collected in 1984, 1986, and 1990, using a validated semiquantitative food frequency questionnaire.ParticipantsA total of 68,782 women aged 37 to 64 years without previously diagnosed angina, myocardial infarction (MI), stroke, cancer, hypercholesterolemia, or diabetes at baseline.Main Outcome MeasureIncidence of acute MI or death due to CHD by amount of fiber intake.ResultsResponse rate averaged 80% to 90% during the 10-year follow-up. We documented 591 major CHD events (429 nonfatal MIs and 162 CHD deaths). The age-adjusted relative risk (RR) for major CHD events was 0.53 (95% confidence interval [CI], 0.40-0.69) for women in the highest quintile of total dietary fiber intake (median, 22.9 g/d) compared with women in the lowest quintile (median, 11.5 g/d). After controlling for age, cardiovascular risk factors, dietary factors, and multivitamin supplement use, the RR was 0.77 (95% CI, 0.57-1.04). For a 10-g/d increase in total fiber intake (the difference between the lowest and highest quintiles), the multivariate RR of total CHD events was 0.81 (95% CI, 0.66-0.99). Among different sources of dietary fiber (eg, cereal, vegetables, fruit), only cereal fiber was strongly associated with a reduced risk of CHD (multivariate RR, 0.63; 95% CI, 0.49-0.81 for each 5-g/d increase in cereal fiber).ConclusionsOur findings in women support the hypothesis that higher fiber intake, particularly from cereal sources, reduces the risk of CHD.

Smoking, Antioxidant Vitamins, and the Risk of Hip Fracture

Abstract: Smoking increases the concentrations of free radicals, which have been suggested to be involved in bone resorption. We examined whether the dietary intake of antioxidant vitamins may modify the increased hip fracture risk associated with smoking. We prospectively studied 66,651 women who were 40-76 years of age. Forty-four of the cohort members who sustained a first hip fracture within 2-64 months of follow-up (n = 247) and 93 out of 873 age-matched controls were current smokers. Information on diet was obtained by a validated food-frequency questionnaire. The relative risk of hip fracture for current versus never smokers was analyzed in relation to the dietary intake of antioxidant vitamins stratified into two categories (low/high), where median intakes among the controls were used as cut-off points. After adjustment for major osteoporosis risk factors, the odds ratio (OR) for hip fracture among current smokers with a low intake of vitamin E was 3.0 (95% confidence interval 1.6-5.4) and of vitamin C 3.0 (1.6-5.6). In contrast, the OR decreased to 1.1 (0.5-2.4) and 1.4 (0.7-3.0) with high intakes of vitamin E and C, respectively. This effect was not seen for beta-carotene, selenium, calcium, or vitamin B6. In current smokers with a low intake of both vitamins E and C, the OR increased to 4.9 (2.2-11.0). The influence of the intake of these two antioxidant vitamins on hip fracture risk was less pronounced in former smokers. Our results suggest a role for oxidant stress in the adverse effects on the skeleton of smoking, and that an insufficient dietary intake of vitamin E and C may substantially increase the risk of hip fracture in current smokers, whereas a more adequate intake seems to be protective.

The role of diabetes mellitus in the aetiology of renal cell cancer

Abstract: To investigate the relation between diabetes mellitus and the risk of renal cell cancer we carried out a population-based retrospective cohort study. Patients identified in the Swedish Inpatient Register who were discharged from hospitals with a diagnosis of diabetes mellitus between 1965 and 1983 formed a cohort of 153 852 patients (80 005 women and 73 847 men). The cohort members were followed up to 1989 by record linkage to three nation-wide registries. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were computed using age-specific sex-specific and period-specific incidence and mortality rates derived from the entire Swedish population. After exclusion of the first year of observation, a total of 267 incidences of renal cell cancer (ICD-7 : 180.0) occurred in diabetic patients compared with the 182.4 that had been expected. Increased risks were observed in both women (SIR = 1.7, 95 % confidence interval, CI = 1.4–2.0) and men (SIR = 1.3; 95 % CI = 1.1–1.6) throughout the duration of follow-up (1–25 years). A higher risk was seen for kidney cancer (ICD-7 : 180) mortality (SMR = 1.9; 95 % CI = 1.7–2.2, women; SMR 1.7, 95 % CI = 1.4–1.9, men). In comparison with the general population, patients with diabetes mellitus have an increased risk of renal cell cancer. [Diabetologia (1999) 42: 107–112]

Higher relative, but lower absolute risks of myocardial infarction in women than in men: analysis of some major risk factors in the SHEEP study. The SHEEP Study Group.

Abstract: . Reuterwall C, Hallqvist J, Ahlbom A, de Faire U, Diderichsen F, Hogstedt C, Pershagen G, Theorell T, Wiman B, Wolk A, the S heep Study Group (National Institute for Working Life; Karolinska Institute; Karolinska Hospital; and National Institute for Psychosocial Factors and Health, Solna; and the Stockholm County Council, Stockholm, Sweden). Higher relative, but lower absolute risks of myocardial infarction in women than in men: analysis of some major risk factors in the S heep study. J Intern Med 1999; 246: 161–174. Objectives. Middle-aged men have often been the subjects of multifactorial studies of myocardial infarction (MI) risk factors. One major objective of the S heep study was to compare the effects of different MI risk factors in women and men. Design. S heep (Stockholm Heart Epidemiology Program) is a population-based case-referent study of causes of MI (first event) in Swedish women and men aged 45–70 years. During the period 1992–94, 2246 cases of MI were identified; 34% of the cases were women and 27% of the cases were fatal. One referent per case was chosen randomly from the Stockholm County population after stratification for the case’s sex and age. Logistic regression was used to estimate the relative risks associated with risk factors of primary interest (diabetes, hypercholesterolaemia, hypertriglyceridaemia , hypertension, overweight, physical inactivity, smoking and job strain). Results. The relative risk estimates ranged from 1.5 to 4.4 in women and from 1.3 to 2.9 in men (results for nonfatal cases and their referents). None of the 95% confidence intervals included 1.0. The relative risks were higher in the women than in the men (101–180%). The absolute risks, however, were all lower in the women than in the men. Estimates of Rothman’s synergy index for gender ranged from 1.0 (hypertension) to 1.8 (current smoking). Conclusions. The indications of some effect modification due to sex (stronger risks in men for certain exposures) invoke the question of possible mechanisms.

Occupational physical activity and risk for breast cancer in a nationwide cohort study in Sweden.

Abstract: Objective: Our purpose was to investigate effects of physical activity on risk for breast cancer

Insulin-Like Growth Factor-Binding Protein-1 and Prostate Cancer

Abstract: There is growing and persuasive evidence, both experimental (1–4) and epidemiologic (5–7), that the peptide hormone insulin-like growth factor-I (IGF-I) is a critical factor in the development of prostate cancer. Because of their central role in the regulation of bioavailable IGF-I, the insulin-like growth factor-binding proteins (IGFBPs) have also come under scrutiny as potential mediators of prostate cancer risk (8–12). There is considerable disagreement concerning which, if any, of the IGFBPs are relevant to the development of prostate cancer. Epidemiologically, IGFBP-3 has been examined (5,7), primarily because more than 95% of circulating IGF-I is bound to this protein (13) together with an acid labile subunit (ALS, a protein synthesized in the liver). The IGF-I/ IGFBP-3/ALS complex is too large (150 kd), however, to pass through blood vessel endothelial cells and affect target tissue (14). It is IGFBP-1 that effectively shuttles IGF-I across blood vessel membranes (15,16). Therefore, it would be expected that blood levels of IGFBP-1 be predictive of the amount of circulating IGF-I available to prostate tissue and thus of prostate cancer risk. We measured IGFBP-1 levels in the serum of 208 patients with prostate cancer and in 70 healthy male control subjects. Informed written consent was obtained from all subjects, and the study was approved by the Research Ethics Committee at the Regional Hospital in Orebro, Sweden (Orebro Lans Landsting). Serum IGF-I and IGFBP-3 were previously measured in these control subjects, and the findings indicated that IGF-I increased the risk of prostate cancer, whereas no demonstrable effect of IGFBP-3 was noted (7). Details of this study have previously been published (7). Briefly, we identified all incident prostate cancer cases in Orebro County, Sweden, from January 1989 through September 1991 and frequency matched them (in 10-year age groups) to healthy control subjects selected from the county population register. Control subjects underwent a digital rectal examination and a serum prostate-specific antigen screening test to avoid inclusion of men with occult disease. Height and weight data were obtained during a physical examination of all participants. Blood samples were drawn from 240 case patients and 235 control subjects, all between 8:00 AM and 10:00 AM. The majority of the blood samples provided by case patients were collected within 4–6 weeks after the initial prostate cancer diagnosis. All samples were centrifuged at 1200g for 10 minutes at room temperature and stored as serum at −70 °C. The imbalance of case patient and control subject serum specimens available for this analysis is a consequence of collecting more blood from the case patients than from the control subjects at the outset of the study. Serum IGF-I and IGFBP-3 levels were determined as previously described (7), both with commercially available immunoradiometric kits (Diagnostic Systems Laboratories, Webster, TX). Serum levels of IGFBP-1 were measured by use of radioimmunoassay (17). The antibodies used were raised in rabbits against purified human amniotic protein, and the cross-reaction with IGFBP-2 and IGFBP-3 was less than 0.1%. The assay measures both nonphosphorylated and phosphorylated forms. Case patients and control subjects were of similar age, height, and body mass index (weight in kilograms/height in meters squared), and case patients had higher levels of IGF-I and somewhat higher levels of IGFBP-3 (Table 1). Serum IGFBP-1 levels were markedly and statistically significantly higher among the case patients (mean, 23.7 ng/mL; standard deviation [SD], 18.3 ng/mL) than among the control subjects (mean, 14.4 ng/mL; SD, 11.6 ng/mL) (Student’s t test; two-tailed P<.0001). We employed logistic regression to estimate the odds ratio (OR) associated with different circulating levels of IGFBP-1 (Table 2). We initially categorized IGFBP-1 according to approximate quartiles of the control distribution by using the lowest quartile (o7.8 ng/ mL) as the referent group. Prostate cancer risk for the second quartile (7.9–10 ng/mL) did not differ from that of the referent quartile; these two quartiles were, therefore, combined to achieve more stable effect estimates. Our results indicate that prostate cancer risk elevation is particularly striking for IGFBP-1 levels more than 17 ng/mL. After we controlled for age, body mass index, and height, circulating IGFBP-1 levels above 17 ng/mL corresponded to a more than fivefold increase in prostate cancer risk (OR 4 5.1; 95% confidence interval 4 2.4–10.7). After our results were further adjusted for IGF-I and IGFBP-3, IGFBP-1 remained an equally strong and statistically significant risk factor for prostate cancer. Serum IGFBP-1 levels vary substantially with metabolic state; they are highest in a fasting and lowest in a fed state (18,19). Although we could not account for variation in the time since last food consumption, all blood samples were taken during the same narrow time-of-day window. So far as time of day (in this case, between 8:00 AM and 10:00 AM) is associated with eating habits, we have controlled for this factor. The size of our control group, al-

Occupational physical activity and renal cell cancer: a nationwide cohort study in Sweden.

Abstract: The causes of renal cell cancer remain incompletely understood. In one previous retrospective case-control study, high occupational physical activity has been associated with a decreased risk among men, but not among women. Our aim was to investigate the association between occupational physical activity and renal cell cancer in a large cohort in Sweden. A cohort of Swedish men and women was identified in the nationwide censuses in 1960 and 1970, and the reported occupations were classified into 4 levels of physical demands. Follow-up from 1971 through 1989 was accomplished through record linkages to the Swedish Cancer Registry. Multivariate Poisson regression models were used to estimate relative risk (RR) and 95% confidence intervals (CI). We found a monotonic increase in risk of renal cell cancer with decreasing level of occupational physical activity among men (p for trend 0.50). Occupational physical activity was inversely associated with renal cell cancer among men. The absence of association among women might be due to smaller range of exposure, confounding by household work or reproductive factors, or to a difference in biological response to physical activity in men and women.