Exacerbations of existing low back pain (LBP) or new LBP episodes are colloquially referred to as “flares”. Although the experience of flares is common to many people with LBP, few validated measures enable people to self-report if they are experiencing a flare. This study examined the convergent validity of a person-dependent definition of flares (“a worsening of your low back pain that lasts from hours to weeks”) as compared to (1) LBP intensity, (2) LBP-related pain interference, and (3) analgesic use, in a large, prospective research study of Veterans with LBP. Veterans seeking care for LBP (n=465) were followed prospectively for up to 1 year. Participants completed up to 36 scheduled surveys and additional patient-initiated surveys (triggered by the onset of new flares) over follow-up. Each survey inquired about current flare status, pain intensity measured on a 0 to 10 numeric rating scale (NRS), LBP-related pain interference, and analgesic use. Linear mixed-effects models estimated the association between current flare status and pain intensity, with and without adjustment for potential confounding factors; secondary analyses examined associations with pain interference and analgesic use. In longitudinal analyses of 11,817 surveys, flare status was significantly associated with a 2.8-NRS-point greater pain intensity (p<0.0001), with and without adjustment for other factors. Statistically significant associations were found between flare status and LBP-related pain interference and analgesic use. New flare periods were associated with impacts on coping, functional limitations, and mood/emotions. These findings support the convergent validity of a person-dependent flare definition.

SUMMARY A person-dependent definition of “flare” among individuals with low back pain has convergent validity as shown by its associations with pain intensity and pain interference.

The authors have declared no competing interest.

Dr. Suri, Dr. Korpak, Mr. Timmons, Ms. Tanus, Ms. Brubeck, and Dr. Daniels are employees of the VA Puget Sound Health Care System in Seattle, Washington. This research was supported by grant I01RX003248 from the Rehabilitation Research and Development Service, VA Office of Research and Development. Drs. Suri, Heagerty, and Rundell are Core Directors of the University of Washington Clinical Learning, Evidence And Research (CLEAR) Center for Musculoskeletal Research, which is funded by P30AR072572 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the US Department of Veterans Affairs, the National Institutes of Health, or the US Government. The authors have no conflicts of interest. Dr. Hodges is supported by a fellowship from the National Health and Medical Research Council (Australia; #1194937). Dr. Staab was supported by a postdoctoral fellowship from the National Center for Complementary and Integrative Health (NCCIH), funded by T90 AT008544.

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This study received human subjects research approval from the VA Puget Sounds Health Care System Institutional Review Board (01860).

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