ReviewPloS one2014
Results of observational studies: analysis of findings from the Nurses' Health Study.
Review in PloS one, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers, 1 of them a synthesis that pooled 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.
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.
Who cites it
10 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Health risk behaviours, mental health and HbA1c: an overview of reviews of observational studies.BMJ open · 2025Pooled it
- Factors Associated With Favorable Laser Trabeculoplasty Response: IRIS Registry Analysis.American journal of ophthalmology · 2021Article
- Comparison of the outcomes of the prolonged antianginal therapy use in stable coronary artery disease patients according to the data of randomized and observational studies.Contemporary clinical trials communications · 2021Article
- Big Health Data and Cardiovascular Diseases: A Challenge for Research, an Opportunity for Clinical Care.Frontiers in medicine · 2019Review
- Assessment of research waste part 1: an exemplar from examining study design, surrogate and clinical endpoints in studies of calcium intake and vitamin D supplementation.BMC medical research methodology · 2018Article
- Medical big data: promise and challenges.Kidney research and clinical practice · 2017Article
- Assessment of sugar-sweetened beverage consumption and weight change: a prospective cohort study.BMC nutrition · 2017Article
- Long-Term Cohort Studies in Brazil: On the Tracks of the Nurses' Health Study and Beyond.American journal of public health · 2016Article
- Food science and food ingredients: the need for reliable scientific approaches and correct communication, Florence, 24 March 2015.International journal of food sciences and nutrition · 2016Article
- Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThe role of observational studies in informing clinical practice is debated, and high profile examples of discrepancies between the results of observational studies and randomised controlled trials (RCTs) have intensified that debate. We systematically reviewed findings from the Nurses' Health Study (NHS), one of the longest and largest observational studies, to assess the number and strength of the associations reported and to determine if they have been confirmed in RCTs.
methodsWe reviewed NHS publication abstracts from 1978-2012, extracted information on associations tested, and graded the strength of the reported effect sizes. We searched PubMed for RCTs or systematic reviews for 3 health outcomes commonly reported in NHS publications: breast cancer, ischaemic heart disease (IHD) and osteoporosis. NHS results were compared with RCT results and deemed concordant when the difference in effect sizes between studies was ≤0.15.
findings2007 associations between health outcomes and independent variables were reported in 1053 abstracts. 58.0% (1165/2007) were statistically significant, and 22.2% (445/2007) were neutral (no association). Among the statistically significant results that reported a numeric odds ratio (OR) or relative risk (RR), 70.5% (706/1002) reported a weak association (OR/RR 0.5-2.0), 24.5% (246/1002) a moderate association (OR/RR 0.25-0.5 or 2.0-4.0) and 5.0% (50/1002) a strong association (OR/RR ≤0.25 or ≥4.0). 19 associations reported in NHS publications for breast cancer, IHD and osteoporosis have been tested in RCTs, and the concordance between NHS and RCT results was low (≤25%).
conclusionsNHS publications contain a large number of analyses, the majority of which reported statistically significant but weak associations. Few of these associations have been tested in RCTs, and where they have, the agreement between NHS results and RCTs is poor.
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What OpenQuestion holds
Registered trials
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.