Often clinical researchers will use data from medical records to try to uncover clues to treatment effectiveness. This is exactly what a group in Michigan did. They took medical records from hospitalized COVID-19 patients and used statistical approaches to evaluate if patients receiving hydroxychloroquine fared better or worse than patients who did not. Although this type of study has limitations, the researchers found evidence that hydroxychloroquine could benefit patients if given early and in a lower dose than was used in some random controlled trials that did not find a benefit.
