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- Andreassen, BK, et al.
(författare)
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Identification of potential carcinogenic and chemopreventive effects of prescription drugs: a protocol for a Norwegian registry-based study
- 2019
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 9:4, s. e028504-
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Tidskriftsartikel (refereegranskat)abstract
- Surveillance of unintended effects of pharmaceuticals (pharmacovigilance or drug safety) is crucial, as knowledge of rare or late side effects is limited at the time of the introduction of new medications into the market. Side effects of drugs may involve increased or decreased risk of cancer, but these typically appear after a long induction period. This fact, together with low incidences of many cancer types, limits the usefulness of traditional pharmacovigilance strategies, primarily based on spontaneous reporting of adverse events, to identify associations between drug use and cancer risk. Postmarketing observational pharmacoepidemiological studies are therefore crucial in the evaluation of drug-cancer associations.Methods and analysisThe main data sources in this project will be the Norwegian Prescription Database and the Cancer Registry of Norway. The underlying statistical model will be based on a multiple nested case–control design including all adult (~200 000) incident cancer cases within the age-range 18–85 years from 2007 through 2015 in Norway as cases. 10 cancer-free population controls will be individually matched to these cases with respect to birth year, sex and index date (date of cancer diagnosis). Drug exposure will be modelled as chronic user/non-user by counting prescriptions, and cumulative use by summarising all dispensions’ daily defined doses over time. Conditional logistic regression models adjusted for comorbidity (National Patient Register), socioeconomic parameters (Statistics Norway), concomitant drug use and, for female cancers, reproduction data (Medical Birth Registry), will be applied to identify drug-use–cancer-risk associations.Ethics and disseminationThe study is approved by the regional ethical committee and the Norwegian data protection authority. Results of the initial screening step and analysis pipeline will be described in a key paper. Subsequent papers will report the evaluation of identified signals in replication studies. Results will be published in peer-reviewed journals, at scientific conferences and through press releases.
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| 3. |
- Botteri, E, et al.
(författare)
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Menopausal hormone therapy and colorectal cancer: a linkage between nationwide registries in Norway
- 2017
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 7:11, s. e017639-
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Tidskriftsartikel (refereegranskat)abstract
- With the present study, we aimed to investigate the association between menopausal hormone therapy (HT) and risk of colorectal cancer (CRC).SettingCohort study based on the linkage of Norwegian population-based registries.ParticipantsWe selected 466822 Norwegian women, aged 55–79, alive and residing in Norway as of 1 January 2004, and we followed them from 2004 to 2008. Each woman contributed person-years at risk as non-user, current user and/or past HT user.Outcome measuresThe outcome of interest was adenocarcinoma of the colorectal tract, overall, by anatomic site and stage at diagnosis. Incidence rate ratios (RRs) with 95% CIs were estimated by Poisson regression and were used to evaluate the association between HT and CRC incidence.ResultsDuring the median follow-up of 4.8 years, 138 655 (30%) women received HT and 3799 (0.8%) incident CRCs occurred. Current, but not past, use of HT was associated with a lower risk of CRC (RR 0.88; 95% CI 0.80 to 0.98). RRs for localised, regionally advanced and metastatic CRC were 1.13 (95% CI 0.91 to 1.41), 0.81 (95% CI 0.70 to 0.94) and 0.79 (95% CI 0.62 to 1.00), respectively. RRs for current use of oestrogen therapy (ET) were 0.91 (95% CI 0.80 to 1.04) while RR for current use of combined oestrogen–progestin therapy (EPT) was 0.85 (95% CI 0.70 to 1.03), as compared with no use of HT. The same figures for ET and EPT in oral formulations were 0.83 (95% CI 0.68 to 1.03) and 0.86 (95% CI 0.71 to 1.05), respectively.ConclusionsIn our nationwide cohort study, HT use lowered the risk of CRC, specifically the most advanced CRC.
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| 8. |
- Stoer, NC, et al.
(författare)
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Is the matched extreme case-control design more powerful than the nested case-control design?
- 2019
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Ingår i: Statistical methods in medical research. - : SAGE Publications. - 1477-0334 .- 0962-2802. ; 28:6, s. 1911-1923
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Tidskriftsartikel (refereegranskat)abstract
- For time-to-event data, the study sample is commonly selected using the nested case–control design in which controls are selected at the event time of each case. An alternative sampling strategy is to sample all controls at the same (pre-specified) time, which can either be at the last event time or further out in time. Such controls are the long-term survivors and may therefore constitute a more ‘extreme’ comparison group and be more informative than controls from the nested case–control design. We investigate this potential information gain by comparing the power of various ‘extreme’ case–control designs with that of the nested case–control design using simulation studies. We derive an expression for the theoretical average information in a nested and extreme case–control pair for the situation of a single binary exposure. Comparisons reveal that the efficiency of the extreme case–control design increases when the controls are sampled further out in time. In an application to a study of dementia, we identified Apolipoprotein E as a risk factor using a 1:1 extreme case–control design, which provided a hazard ratio estimate with a smaller standard error than that of a 2:1 nested case–control design.
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