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Comment & Response
August 6, 2019

Tramadol and Mortality in Patients With Osteoarthritis

Author Affiliations
  • 1Boston University School of Medicine, Boston, Massachusetts
JAMA. 2019;322(5):465-466. doi:10.1001/jama.2019.7216

To the Editor Confounding by indication occurs when the clinical indication for selecting a particular treatment, such as severity of disease, also affects outcomes.1 Even with careful data analysis, intractable confounding can occur because the data set does not contain data detailed enough to allow investigators to adjust sufficiently for comorbidities and disease severity.