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- Blomgren, K. J., et al.
(författare)
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Interviewer variability - quality aspects in a case-control study
- 2006
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Ingår i: Eur J Epidemiol. - : Springer Science and Business Media LLC. - 0393-2990 .- 1573-7284. ; 21:4, s. 267-77
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Tidskriftsartikel (refereegranskat)abstract
- Quality assurance and quality control are important for the reliability of case-control studies. Here we describe the procedures used in a previously published study, with emphasis on interviewer variability. To evaluate risk factors for acute pancreatitis, information including previous diagnoses and medication was collected from medical records and by telephone interviews from 462 cases and 1781 controls. Quality assurance procedures included education and training of interviewers and data validity checks. Quality control included a classification test, annual test interviews, expert case validation, and database validation. We found pronounced variations between interviewers. The maximal number of interviews per day varied from 3 to 9. The adjusted average (95% CI) number of diagnoses captured per interview of cases was 4.1 (3.8-4.3) and of controls 3.5 (3.4-3.7) (excluding one deviating interviewer). For drugs, the average (95% CI) number per interview was 3.9 (3.7-4.1) for cases and 3.3 (3.2-3.4) for controls (excluding one deviating interviewer). One of the fourteen interviewers deviated significantly from the others, and more so for controls than for cases. This interviewer's data ;were excluded. Nonetheless, data concerning controls more frequently needed correction and supplementation than for cases. Erroneous coding of diagnoses and medication was also more frequent among controls. Thus, a system for quality control of coding practices is crucial. Variability in interviewers' ability to ascertain information is a possible source of bias in interview-based case-control studies when "blinding" cannot be achieved.
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| 2. |
- Bälter, Olle, 1962-, et al.
(författare)
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Demands on web survey tools for epidemiological research
- 2005
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Ingår i: European Journal of Epidemiology. - Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden. : Springer Science and Business Media LLC. - 0393-2990 .- 1573-7284. ; 20:2, s. 137-139
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Tidskriftsartikel (refereegranskat)abstract
- In countries where the Internet access is high, a web-based questionnaire could save time and money compared to printed questionnaires, mainly by eliminating the two steps of transferring answers from printed to a digital data set and manually completing missing and impossible answers. However, many of the features wanted for conducting large epidemiological studies are not available in many web survey systems. Here we describe design issues the investigator needs to be aware of when using web-based questionnaires in epidemiological research.
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| 3. |
- Lagerros, Y. T., et al.
(författare)
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Validity and reliability of self-reported total energy expenditure using a novel instrument
- 2006
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Ingår i: European Journal of Epidemiology. - Karolinska Inst, Dept Med Epidemiol & Biostat, SE-17177 Stockholm, Sweden. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Univ Milano Bicocca, Dept Stat, Milan, Italy. Royal Inst Technol, Sch Comp Sci & Commun, Stockholm, Sweden. : Springer Science and Business Media LLC. - 0393-2990 .- 1573-7284. ; 21:3, s. 227-236
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Tidskriftsartikel (refereegranskat)abstract
- Improved methods for quantitative self-reports of total physical activity in epidemiological studies are needed. We evaluated randomly selected individuals' ability to integrate their perception of physical activity over time to produce an estimate of the usual level, using a novel instrument for self-quantification of energy expenditure. A population-based sample of 418 Swedish men and women, age 20-59, completed a questionnaire containing the new instrument. For validation, three 24 hour recalls by phone served as gold standard. Reproducibility was assessed through administering the instrument another three times. The validation involved 133 subjects and another 160 completed the reproducibility evaluation. Pearson correlation between usual daily energy expenditure measured by the instrument and the mean of the 24 hour recalls was 0.73. After subdividing the self-reported daily energy expenditure and the mean of the 24 hour recalls into quintiles, 83.5% of the participants remained in the same quintile, or one quintile apart. There was a tendency towards overestimation of usual daily physical activity. This was significantly associated with low education. Reproducibility showed an intraclass correlation of 0.55. Although integrated reports of usual daily energy expenditure over longer periods seem to be afflicted with a tendency of overestimation, total energy expenditure can be estimated with reasonable validity and reproducibility using our instrument.
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| 6. |
- Wiklund, Fredrik, et al.
(författare)
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Lifetime total physical activity and prostate cancer risk : a population-based case-control study in Sweden
- 2008
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Ingår i: European Journal of Epidemiology. - Berlin : Springer. - 0393-2990 .- 1573-7284. ; 23:11, s. 739-746
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Tidskriftsartikel (refereegranskat)abstract
- The etiologic role of physical activity in prostate cancer development is unclear. We assessed the association between lifetime total physical activity and prostate cancer risk in a Swedish population-based case–control study comprising 1,449 incident prostate cancer cases and 1,118 unaffected population controls. Information regarding physical activity was obtained via a self-administered questionnaire assessing occupational, household, and recreational activity separately at various ages throughout an individual’s lifetime. Clinical data (TNM-classification, Gleason sum and PSA) was obtained from linkage to the National Prostate Cancer Registry. Overall, we observed no association between lifetime total physical activity and prostate cancer risk (odds ratio [OR] = 1.04, 95% confidence interval [CI] = 0.77–1.41 for ≥49.7 vs. <41.9 metabolic equivalent-hours per day). There was a significantly increased risk of prostate cancer in the most active men compared with the least active men in household (OR = 1.44, 95% CI = 1.08–1.92) and recreational physical activity (OR = 1.56, 95% CI = 1.16–2.10). Comparing the most active with the least active men, total physical activity was not associated with either localized disease (OR = 0.95, 95% CI = 0.67–1.34) or advanced disease (OR = 1.19, 95% CI = 0.83–1.71). These findings do not support the hypothesis that physical activity uniformly protects against prostate cancer development.
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