Evidence map›Paper›PMID 41820738›Full record

Trial reportJournal of general internal medicine2026

Estimating the Hawthorne Effect in Real-World Blood Pressure Control Trials: An Analysis of the BP Home Trial.

Max Rosen, Valy Fontil, Madelaine Faulkner Modrow, Steven M Smith, Thomas W Carton, Alanna M Chamberlain, Emily C O'Brien, Soo Park, Jaime Orozco, Rhonda M Cooper DeHoff and 4 more

Erratum issued Registry-linked trialAbstract readRandomized Controlled TrialPragmatic Clinical Trial
PubMed Full text at PMC Publisher
In one paragraph

Trial report in Journal of general internal medicine, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. It is linked to trial NCT03796689 (The PCORnet Blood Pressure Home Monitoring Study), which is not on this map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
–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.

NCT03796689 nacompletednot on this map

The PCORnet Blood Pressure Home Monitoring Study

TypeinterventionalSponsorUniversity of California, San FranciscoRan2019 to 2021Enrolled2,238ConditionsHypertensionArmsSmartphone-linked HBPM and associated app, Standard HBPM
3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

14 authors.

Max RosenDepartment of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA. mr1832@rwjms.rutgers.edu.ORCID 0000-0002-2845-2821
Valy FontilDepartment of Population Health and Institute of Excellence in Health Equity, NYU Grossman School of Medicine, New York, NY, USA.
Madelaine Faulkner ModrowDepartment of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
Steven M SmithDepartment of Pharmaceutical Outcomes & Policy, College of Pharmacy, University of Florida, Gainesville, FL, USA.
Thomas W CartonLouisiana Public Health Institute, New Orleans, LA, USA.
Alanna M ChamberlainDepartment of Quantitative Health Sciences, and Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
Emily C O'BrienDuke Clinical Research Institute and Duke University School of Medicine, Durham, NC, USA.
Soo ParkDepartment of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
Jaime OrozcoDepartment of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
Rhonda M Cooper DeHoffDepartment of Pharmacotherapy and Translational Research, College of Pharmacy and Division of Cardiovascular Medicine, College of Medicine, University of Florida, Gainesville, FL, USA.
Gregory WozniakAmerican Medical Association, Chicago, IL, USA.
Michael RakotzAmerican Medical Association, Chicago, IL, USA.
Charles E McCullochDepartment of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
Mark J PletcherDepartment of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.

Funding

Patient-Centered Outcomes Research Institute PaCR-2017C2-8153
6 · The paper itself

Abstract

backgroundResults from blood pressure (BP) control interventional trials can inform clinicians and health systems pursuing better BP control, but they must be interpreted cautiously.

objectiveDeconstruct the observed drop in systolic BP (SBP) into components attributable to increased adherence to previously prescribed medications, regression to the mean, and initiation of new medications.

designSecondary analysis of BP Home, a pragmatic randomized controlled trial.

participantsPatients owning a smartphone who reported uncontrolled BP at their last clinic visit (> 145 mmHg) and a desire to lower their BP by > 10 mmHg.

interventionsIn BP Home, participants were randomly assigned to receive one of two devices for self-measurement of BP and followed for up to 24 months via electronic health records (EHR). APPROACH: The primary outcome was EHR-recorded office SBP. We fit SBP trajectories for each participant using linear mixed models, and estimated the contributions of medication adjustments, and increased adherence to pre-existing BP medications due to their enrollment in a research study (i.e., a Hawthorne effect). Regression to the mean was calculated for each participant as the difference between their last measured pre-enrollment SBP and their modeled SBP trajectory at enrollment. KEY

resultsAmong participants taking BP medications at enrollment, we estimated an average immediate drop in SBP of -4.2 mmHg (95% CI, -5.1 to -3.3; p < 0.001) at enrollment, explainable by increased medication adherence following study enrollment. Starting a new medication class post-enrollment resulted in an SBP drop of -4.1 mmHg (95% CI, -5.3 to -2.8; p < 0.001). The average expected regression to the mean was -3.9 (95% CI, -4.4 to -3.3; p < 0.001).

conclusionsA significant portion of BP reductions in trials may stem from increased adherence to pre-existing medications arising from enrollment in a research study and enhanced awareness of their elevated BP. NIH TRIAL REGISTRY NUMBER: NCT03796689 (registered on 2019-01-04).

Indexed as

Antihypertensive AgentsBlood PressureBlood Pressure Monitoring, AmbulatoryHypertensionMedication AdherenceAgedEffect Modifier, EpidemiologicFemaleHumansMaleMiddle AgedAntihypertensive AgentsHawthorne effecthypertensionmixed regression modelregression to the mean

Identifiers

PMID41820738
PMCPMC13569757

What OpenQuestion holds

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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.