Evidence map›Paper›PMID 28317167›Full record

ArticleGenetic epidemiology2017

Semiparametric methods for estimation of a nonlinear exposure-outcome relationship using instrumental variables with application to Mendelian randomization.

James R Staley, Stephen Burgess

Abstract read
In one paragraph

Article in Genetic epidemiology, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 166 papers, 8 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
166citing papers in PubMed, 8 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

166 citing papers in PubMed, 8 syntheses or guidelines pooled it.

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  7. High Blood Pressure and Intraocular Pressure: A Mendelian Randomization Study.Investigative ophthalmology & visual science · 2022
    Pooled it
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  9. Leukocytes and age-related macular degeneration.European journal of epidemiology · 2026
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106 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

2 authors.

James R StaleyStrangeways Research Laboratory, Department of Public Health and Primary Care, Cardiovascular Epidemiology Unit, University of Cambridge, United Kingdom.
Stephen BurgessStrangeways Research Laboratory, Department of Public Health and Primary Care, Cardiovascular Epidemiology Unit, University of Cambridge, United Kingdom.ORCID 0000-0001-5365-8760

Funding

British Heart Foundation RG/08/014/24067British Heart Foundation RG/13/13/30194British Heart Foundation SP/09/002European Research Council 268834Medical Research Council G0800270Medical Research Council G66840Medical Research Council MC_QA137853Medical Research Council MC_UP_0801/1Medical Research Council MC_UU_00002/7Medical Research Council MR/L003120/1Wellcome Trust 100114Wellcome Trust 204623/Z/16/Z
6 · The paper itself

Abstract

Mendelian randomization, the use of genetic variants as instrumental variables (IV), can test for and estimate the causal effect of an exposure on an outcome. Most IV methods assume that the function relating the exposure to the expected value of the outcome (the exposure-outcome relationship) is linear. However, in practice, this assumption may not hold. Indeed, often the primary question of interest is to assess the shape of this relationship. We present two novel IV methods for investigating the shape of the exposure-outcome relationship: a fractional polynomial method and a piecewise linear method. We divide the population into strata using the exposure distribution, and estimate a causal effect, referred to as a localized average causal effect (LACE), in each stratum of population. The fractional polynomial method performs metaregression on these LACE estimates. The piecewise linear method estimates a continuous piecewise linear function, the gradient of which is the LACE estimate in each stratum. Both methods were demonstrated in a simulation study to estimate the true exposure-outcome relationship well, particularly when the relationship was a fractional polynomial (for the fractional polynomial method) or was piecewise linear (for the piecewise linear method). The methods were used to investigate the shape of relationship of body mass index with systolic blood pressure and diastolic blood pressure.

Indexed as

Nonlinear DynamicsBlood PressureBody Mass IndexComputer SimulationGenetic VariationHumansMendelian Randomization AnalysisModels, GeneticModels, StatisticalTissue BanksUnited Kingdomcausal effectsfractional polynomialsgenetic variantspiecewise linear modelsUK Biobank

Identifiers

PMID28317167
PMCPMC5400068

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.