Poor replication validity of biomedical association studies reported by newspapers

Estelle Dumas-Mallet, Andy Smith, Thomas Boraud, François Gonon
PLoS ONE. 2017-02-21; 12(2): e0172650
DOI: 10.1371/journal.pone.0172650

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Dumas-Mallet E(1)(2), Smith A(1), Boraud T(2), Gonon F(2).

Author information:
(1)Centre Emile Durkheim, CNRS UMR5116 at Université de Bordeaux, Pessac, France.
(2)Institute of Neurodegenerative Diseases, CNRS UMR5293 at Université de Bordeaux, Bordeaux, France.

OBJECTIVE: To investigate the replication validity of biomedical association
studies covered by newspapers.

METHODS: We used a database of 4723 primary studies included in 306 meta-analysis
articles. These studies associated a risk factor with a disease in three
biomedical domains, psychiatry, neurology and four somatic diseases. They were
classified into a lifestyle category (e.g. smoking) and a non-lifestyle category
(e.g. genetic risk). Using the database Dow Jones Factiva, we investigated the
newspaper coverage of each study. Their replication validity was assessed using a
comparison with their corresponding meta-analyses.

RESULTS: Among the 5029 articles of our database, 156 primary studies (of which
63 were lifestyle studies) and 5 meta-analysis articles were reported in 1561
newspaper articles. The percentage of covered studies and the number of newspaper
articles per study strongly increased with the impact factor of the journal that
published each scientific study. Newspapers almost equally covered initial (5/39
12.8%) and subsequent (58/600 9.7%) lifestyle studies. In contrast, initial
non-lifestyle studies were covered more often (48/366 13.1%) than subsequent ones
(45/3718 1.2%). Newspapers never covered initial studies reporting null findings
and rarely reported subsequent null observations. Only 48.7% of the 156 studies
reported by newspapers were confirmed by the corresponding meta-analyses. Initial
non-lifestyle studies were less often confirmed (16/48) than subsequent ones
(29/45) and than lifestyle studies (31/63). Psychiatric studies covered by
newspapers were less often confirmed (10/38) than the neurological (26/41) or
somatic (40/77) ones. This is correlated to an even larger coverage of initial
studies in psychiatry. Whereas 234 newspaper articles covered the 35 initial
studies that were later disconfirmed, only four press articles covered a
subsequent null finding and mentioned the refutation of an initial claim.

CONCLUSION: Journalists preferentially cover initial findings although they are
often contradicted by meta-analyses and rarely inform the public when they are

DOI: 10.1371/journal.pone.0172650
PMCID: PMC5319681
PMID: 28222122 [Indexed for MEDLINE]

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