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| 2. |
- Holmberg, Lars, et al.
(författare)
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A search for recall bias in a case-control study of diet and breast cancer
- 1996
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Ingår i: International Journal of Epidemiology. - 0300-5771 .- 1464-3685. ; 25:2, s. 235-244
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND. In retrospective studies of dietary habits and breast cancer risk, recall bias is a concern since diet has been publicized as a cause of breast cancer. METHODS. In a case-control study of diet and breast cancer risk nested within a cohort of women screened with mammography, we contrasted answers to a retrospective dietary interview with answers to a dietary questionnaire which was filled out before any diagnostic procedures for breast cancer were undertaken. The source population was all women aged 40-74 in two counties in Sweden invited to mammographic screening and asked to fill out a questionnaire before the screening. Cases and controls were subsequently defined -- matched on age, county of residence, and time of mammography -- and approached for an interview. RESULTS. In all, 265 cases and 431 controls participated in the study. Means of frequencies differed between the agreement in the questionnaire's and the interview's classifications of study subjects into quartiles of monthly intake varied between 31 percent and 57 percent. Kappa statistics in all food groups were below 0.41. In a regression analysis, case subjects with low responses on the questionnaire about intake of meat, snacks, and coffee and tea gave higher responses on interview than did controls who had low questionnaire responses for these food groups. The reverse was also true: cases' responses that were high on the questionnaire were lower on interview for these food groups than were controls' responses. CONCLUSIONS. We found few signs of recall bias, and the few indications of a differential misclassification that we found were not in food groups that have been publicly discussed as causes of breast cancer.
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| 3. |
- Kuskowska-Wolk, A, et al.
(författare)
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Effects of different designs and extension of a food frequency questionnaire on response rate, completeness of data and food frequency responses
- 1992
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 21:6, s. 1144-50
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Tidskriftsartikel (refereegranskat)abstract
- The authors studied how the introduction of several modifications to a basic food frequency questionnaire can influence the results of dietary surveys. Modifications covered eight combinations based on three levels: increasing versus decreasing order of frequency categories; questionnaires without versus with questions about portion sizes, and questionnaires without versus with extra non-dietary questions. The sample included 6783 women between the ages of 40 and 70 years who took part in mammography screening. The women were randomly assigned to one of the eight study groups. All of the women in each group received one of the eight differently modified questionnaires. The forms extended in length by extra non-dietary questions and portion size categories resulted in a 20% higher total non-response compared to the shorter basic form. Partial non-response was significantly lower for all four questionnaire types that included portion sizes. When portion sizes were included in the questionnaire, the reported mean frequency of consumption was significantly reduced for fat (-10 times per month), milk (-6), bread (-5), vegetables (-2) and fish (-0.4). The decreasing order of responses to the frequency categories was associated with a statistically significant increase in the frequency responses for bread (2.6 times per month), vegetables (2) and fish (0.6). These data provide evidence that the design and extension of food frequency questionnaires influence the results of dietary studies.
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| 4. |
- Ohlander, E, et al.
(författare)
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Neighbourhood non-employment and daily smoking: a population-based study of women and men in Sweden
- 2006
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Ingår i: European Journal of Public Health. - : Oxford University Press (OUP). - 1101-1262 .- 1464-360X. ; 16:1, s. 78-84
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Tidskriftsartikel (refereegranskat)abstract
- Background: To examine whether neighbourhood non-employment is associated with daily smoking after adjustment for individual characteristics, such as employment status. Methods: Cross-sectional study of a simple, random sample of 31,164 women and men aged 25-64, representative of the entire population in Sweden. Data were collected from the years 1993-2000. The individual variables included age, sex, employment status, occupation and housing tenure. Logistic regression was used in the analysis with neighbourhood non-employment rates measured at small area market statistics level. Results: There was a significant association between neighbourhood non-employment rates and daily smoking for both women and men. After adjustment for employment status and housing tenure the odds ratios of daily smoking were 1.39 (95% CI = 1.22-1.58) for women and 1.41 (95% CI = 1.23-1.61) for men living in neighbourhoods with the highest non-employment rates. The individual variables of unemployment, low occupational level and renting were associated with daily smoking. Conclusion: Neighbourhood non-employment is associated with daily smoking. Smoking prevention in primary health care should address both individuals and neighbourhoods.
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| 5. |
- Wolk, A, et al.
(författare)
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Self-administered food frequency questionnaire : the effect of different designs on food and nutrient intake estimates
- 1994
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 23:3, s. 570-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Our objective was to determine the possible influence that different designs of a food frequency questionnaire might have on food, energy and nutrient intake estimates.METHODS: A population-based survey included 6783 women, 40-70 years old, living in central Sweden. Using a factorial study design, we compared eight different types of questionnaire covering combinations of three factors: increasing/decreasing frequency categories; addition of portion sizes; and addition of non-dietary questions. All questionnaires included the same list of 60 food items. One of the eight questionnaires was mailed to each subject according to a random assignment. The overall response rate was 77%.RESULTS: Compared with increasing frequencies, decreasing order of frequency categories entailed 3-11% higher estimates of mean intake for 7 of 14 food groups, 4% higher estimates for energy and 3-6% higher estimates for 13 of 18 nutrients. Addition of portion sizes had heterogeneous effects, both on dietary items (e.g. from -30% decrease for eggs to +76% increase for coffee) and on calculated nutrients (from -7% for beta-carotene to +19% for vitamin C). The inclusion of some additional non-dietary questions did not influence the estimated mean intake of any food or nutrient.CONCLUSIONS: The results of this study have implications for the design of questionnaires and for pooled analyses in nutritional epidemiology, when different food questionnaires are used.
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