This is the peer reviewed version of the following article: Zhao, S.S., Yoshida, K., Jones, G.T., Hughes, D.M., Tedeschi, S.K., Lyu, H., Moots, R.J., Solomon, D.H. and Goodson, N.J. (2020), Impact of Smoking in Response to Tumor Necrosis Factor Inhibitors in Axial Spondyloarthritis: Methodologic Considerations for Longitudinal Observational Studies. Arthritis Care Res, 72: 591-599., which has been published in final form at https://doi.org/10.1002/acr.23851. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.