Related Experiment Videos
Reanalysis of the Harvard Six Cities Study, part I: validation and replication
D Krewski1, R T Burnett, M Goldberg
1McLaughlin Centre for Population Health Risk Assessment, Institute for Population Health, University of Ottawa, Ottawa, Ontario, Canada. dkrewski@uottawa.ca
Inhalation Toxicology
|July 16, 2005
Summary
A reanalysis of the Harvard Six Cities Study confirmed its original findings on air pollution and mortality. The study validated that fine particulate matter (PM2.5) exposure is linked to increased mortality risks.
Area of Science:
- Environmental epidemiology
- Public health research
- Air quality science
Background:
- The Harvard Six Cities Study was pivotal in setting U.S. air quality standards for fine particulate matter (PM2.5).
- Concerns about the original study's findings prompted a call for independent reanalysis.
Purpose of the Study:
- To independently validate the original findings of the Harvard Six Cities Study.
- To audit the data quality and replicate the results concerning particulate air pollution and mortality.
Main Methods:
- A detailed statistical audit and replication of the original study's data and analyses.
- Comparison of original questionnaires with death certificates.
- Updating the cohort data to correct for a programming error causing early censorship.
Main Results:
- The audit found minimal discrepancies, none of epidemiologic importance, between original data and death certificates.
- A programming error led to a loss of ~1% of follow-up data, which was corrected in the reanalysis.
- Reanalysis reproduced original numerical results, including a 26% increase in mortality linked to higher PM2.5 levels.
Conclusions:
- The reanalysis generally confirmed the data quality and numerical results of the original Harvard Six Cities Study.
- The identified discrepancies did not substantively alter the original risk estimates or conclusions.
- The study's findings on the association between particulate air pollution and mortality remain robust.