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BMC Public Health
Published in: BMC Public Health 1/2016

Open Access 01-12-2016 | Research article

The effect of adherence to statin therapy on cardiovascular mortality: quantification of unmeasured bias using falsification end-points

Authors: Maarten J. Bijlsma, Stijn Vansteelandt, Fanny Janssen, Eelko Hak

Published in: BMC Public Health | Issue 1/2016

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Abstract

Background

To determine the clinical effectiveness of statins on cardiovascular mortality in practice, observational studies are needed. Control for confounding is essential in any observational study. Falsification end-points may be useful to determine if bias is present after adjustment has taken place.

Methods

We followed starters on statin therapy in the Netherlands aged 46 to 100 years over the period 1996 to 2012, from initiation of statin therapy until cardiovascular mortality or censoring. Within this group (n = 49,688, up to 16 years of follow-up), we estimated the effect of adherence to statin therapy (0 = completely non-adherent, 1 = fully adherent) on ischemic heart diseases and cerebrovascular disease (ICD10-codes I20-I25 and I60-I69) as well as respiratory and endocrine disease mortality (ICD10-codes J00-J99 and E00-E90) as falsification end points, controlling for demographic factors, socio-economic factors, birth cohort, adherence to other cardiovascular medications, and diabetes using time-varying Cox regression models.

Results

Falsification end-points indicated that a simpler model was less biased than a model with more controls. Adherence to statins appeared to be protective against cardiovascular mortality (HR: 0.70, 95 % CI 0.61 to 0.81).

Conclusions

Falsification end-points helped detect overadjustment bias or bias due to competing risks, and thereby proved to be a useful technique in such a complex setting.
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Metadata
Title
The effect of adherence to statin therapy on cardiovascular mortality: quantification of unmeasured bias using falsification end-points
Authors
Maarten J. Bijlsma
Stijn Vansteelandt
Fanny Janssen
Eelko Hak
Publication date
01-12-2016
Publisher
BioMed Central
Published in
BMC Public Health / Issue 1/2016
Electronic ISSN: 1471-2458
DOI
https://doi.org/10.1186/s12889-016-2986-0

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