• Eur. J. Epidemiol. · Nov 2017

    Immortal time bias in pharmacoepidemiological studies on cancer patient survival: empirical illustration for beta-blocker use in four cancers with different prognosis.

    • Janick Weberpals, Lina Jansen, van Herk-SukelMyrthe P PMPPPHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands., Josephina G Kuiper, Mieke J Aarts, VissersPauline A JPAJNetherlands Comprehensive Cancer Organisation, Utrecht, The Netherlands., and Hermann Brenner.
    • Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
    • Eur. J. Epidemiol. 2017 Nov 1; 32 (11): 1019-1031.

    AbstractImmortal time bias (ITB) is still seen frequently in medical literature. However, not much is known about this bias in the field of cancer (pharmaco-)epidemiology. In context of a hypothetical beneficial beta-blocker use among cancer patients, we aimed to demonstrate the magnitude of ITB among 9876 prostate, colorectal, lung and pancreatic cancer patients diagnosed between 1998 and 2011, which were selected from a database linkage of the Netherlands Cancer Registry and the PHARMO Database Network. Hazard ratios (HR) and 95% confidence intervals from three ITB scenarios, defining exposure at a defined point after diagnosis (model 1), at any point after diagnosis (model 2) and as multiple exposures after diagnosis (model 3), were calculated to investigate the association between beta-blockers and cancer prognosis using Cox proportional hazards regression. Results were compared to unbiased estimates derived from the Mantel-Byar model. Ignoring ITB led to substantial smaller HRs for beta-blocker use proposing a significant protective association in all cancer types [e.g. HR 0.18 (0.07-0.43) for pancreatic cancer in model 1], whereas estimates derived from the Mantel-Byar model were mainly suggesting no association [e.g. HR 1.10 (0.84-1.44)]. The magnitude of bias was consistently larger among cancer types with worse prognosis [overall median HR differences between all scenarios in model 1 and Mantel-Byar model of 0.56 (prostate), 0.72 (colorectal), 0.77 (lung) and 0.85 (pancreas)]. In conclusion, ITB led to spurious beneficial associations of beta-blocker use among cancer patients. The magnitude of ITB depends on the duration of excluded immortal time and the prognosis of each cancer.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…