Evidence map›Paper›PMID 19457638›Full record

ArticleJournal of clinical epidemiology2010

A most stubborn bias: no adjustment method fully resolves confounding by indication in observational studies.

Jaclyn L F Bosco, Rebecca A Silliman, Soe Soe Thwin, Ann M Geiger, Diana S M Buist, Marianne N Prout, Marianne Ulcickas Yood, Reina Haque, Feifei Wei, Timothy L Lash

Abstract readEvaluation Study
PubMed Full text at PMC Publisher
In one paragraph

Article in Journal of clinical epidemiology, 2010. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 178 papers, 13 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
178citing papers in PubMed, 13 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

178 citing papers in PubMed, 13 syntheses or guidelines pooled it.

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  12. A systematic review of surgery for non-curative gastric cancer.Gastric cancer : official journal of the International Gastric Cancer Association and the Japanese Gastric Cancer Association · 2012
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  18. Interpreting Glycopeptide Escalation and Acute Kidney Injury with CautionTurkish journal of haematology : official journal of Turkish Society of Haematology · 2026
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118 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

10 authors.

Jaclyn L F BoscoDepartment of Medicine, Geriatrics Section, Boston University School of Medicine, Boston, MA 02118, USA. jfong@bu.edu
Rebecca A Silliman
Soe Soe Thwin
Ann M Geiger
Diana S M Buist
Marianne N Prout
Marianne Ulcickas Yood
Reina Haque
Feifei Wei
Timothy L Lash

Funding

Long-term Survivorship in Older Women with Early Stage Breast CancerR01CA093772 · NCI · BOSTON MEDICAL CENTER · PI SILLIMAN, REBECCA A · 2003 to 2011
$7.5M
Cancer Control in Older AdultsK05CA092395 · NCI · BOSTON MEDICAL CENTER · PI SILLIMAN, REBECCA A · 2001 to 2010
$1.5M
NCI NIH HHS K05 CA092395NCI NIH HHS R01 CA093772
6 · The paper itself

Abstract

objectiveTo evaluate the effectiveness of methods that control for confounding by indication, we compared breast cancer recurrence rates among women receiving adjuvant chemotherapy with those who did not. STUDY DESIGN AND

settingIn a medical record review-based study of breast cancer treatment in older women (n=1798) diagnosed between 1990 and 1994, our crude analysis suggested that adjuvant chemotherapy was positively associated with recurrence (hazard ratio [HR]=2.6; 95% confidence interval [CI]=1.9, 3.5). We expected a protective effect, so postulated that the crude association was confounded by indications for chemotherapy. We attempted to adjust for this confounding by restriction, multivariable regression, propensity scores (PSs), and instrumental variable (IV) methods.

resultsAfter restricting to women at high risk for recurrence (n=946), chemotherapy was not associated with recurrence (HR=1.1; 95% CI=0.7, 1.6) using multivariable regression. PS adjustment yielded similar results (HR=1.3; 95% CI=0.8, 2.0). The IV-like method yielded a protective estimate (HR=0.9; 95% CI=0.2, 4.3); however, imbalances of measured factors across levels of the IV suggested residual confounding.

conclusionConventional methods do not control for unmeasured factors, which often remain important when addressing confounding by indication. PS and IV analysis methods can be useful under specific situations, but neither method adequately controlled confounding by indication in this study.

Indexed as

BiasConfounding Factors, EpidemiologicAgedAntineoplastic AgentsBreast NeoplasmsChemotherapy, AdjuvantData Interpretation, StatisticalFemaleHumansPropensity ScoreRecurrenceTreatment OutcomeAntineoplastic Agents

Identifiers

PMID19457638
PMCPMC2789188

What OpenQuestion holds

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Registered trials

None linked

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.