The study was not considered human research
If your research involves the use of existing data collected from human participants (e.g., secondary datasets, existing biological samples), but there are no identifiers linking human participants to the data/samples themselves, then the activity may not require IRB review and may be considered "not human participant research".
Additionally, use of existing de-identified or publicly available datasets may not
be considered human subject research. For more information, see the following document: Secondary Analysis of Public Use Datasets.