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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. |
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| 3. |
- Sundström, A., et al.
(författare)
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Acid – suppressing drugs and gastro-esophageal reflux disease as risk factors for acute pancreatitis – results from a Swedish Case-Control Study.
- 2006
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Ingår i: Pharmacoepidemiology and Drug Safety. - : Wiley. - 1053-8569 .- 1099-1557. ; 15:3, s. 141-9
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To study risk factors for acute pancreatitis, here with emphasis on gastro-intestinal diseases and their treatments. METHODS: Population based case-control study covering four areas in Sweden encompassing 2.2 million inhabitants. Included were 462 incident cases of acute pancreatitis aged 20-85 years, hospitalized from 1 January 1995-31 May 1998, and 1,781 unmatched controls randomly selected from the study base using a population register. Information was captured from medical records and structured telephone interviews. RESULTS: Current use of H(2) antagonists starting within 6 months of index-date was associated with acute pancreatitis with an adjusted OR of 4.9 (95% confidence interval (CI) 1.6-15), and current use of proton pump inhibitors (PPIs) with an adjusted OR of 3.2 (95%CI 1.4-7.4). For both drug classes, the ORs tended to be higher at higher doses. Gastritis/gastro-esophageal reflux disease (GERD) within the last 12 months not treated with PPIs or H(2)-antagonists and inflammatory bowel disease (IBD) not treated with anti-inflammatory or immunosuppressive drugs were associated with development of acute pancreatitis with adjusted odds ratios (OR) of 1.9 (95%CI 1.2-3.0) and 5.1 (95%CI 2.0-13) respectively. CONCLUSIONS: Current IBD without treatment and gastritis/GERD without treatment were found to be associated with increased risks to develop acute pancreatitis but the nature of the latter association needs to be further evaluated. On balance, we judge that the observed associations between current use of H(2)-antagonists and PPIs and increased risk of acute pancreatitis are unlikely to be explained by bias.
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