Research Article: Evaluation of the responsiveness of outcome measures after spine injection: A retrospective study

Date Published: February 27, 2019

Publisher: Public Library of Science

Author(s): Jiwoon Seo, Joon Woo Lee, Yusuhn Kang, Eugene Lee, Joong Mo Ahn, Dong Hyun Kim, Heung Sik Kang, Amin Mohamadi.


Discrepancies in patients’ responses to various outcome measures challenge clinicians’ evaluation of treatment outcomes. Therefore, we aimed to 1) evaluate the concordance of outcome measures after spine injection, 2) determine the patient variables that lead to discordant responses, and 3) suggest practical outcome measure for spine injections with good responsiveness. From October 2014 to November 2014, 164 patients with neck or low back pain who visited our outpatient clinics and had spine injections on the previous visit were enrolled. We asked patients to report changes in their symptom in the form of outcome measures: numeric rating scale, Oswestry disability index, neck disability index, residual symptom percentage and global perceived effect. The responses were categorized into three groups according to the degree of change; not improved, minimally improved, and significantly improved. The concordances of these categorized answers were evaluated. When “significantly improved” was considered as true improvement, 46 (28%) of the 164 patients had discordant responses to the four measures. There was no significant patients’ variable that affects discordance in the outcome measures. Good agreement was shown between the global perceived effect and residual symptom percentage, while the Oswestry disability index had poor agreement with the other measurements. The calculated numeric rating scale and residual symptom percentage also had low levels of agreement. However, patients with severe pre-treatment pain tended to have better agreement. In conclusion, this result suggest that the residual symptom percentage may be a more practical for clinicians and better represent patients’ improvements after spine injection.

Partial Text

Low back pain and neck pain are common causes of disability in middle- to old-aged individuals. Since only 10% to 15% of these patients require surgery or are eligible for surgery, conservative management is recommended in most patients. Conservative management may include oral medications, image-guided injections, exercise, or physical therapy. Among these, spine injections have been reported to be effective in localizing and managing low back and neck pain [1, 2].

Among 164 patients, 122 had low back pain with or without lumbar radiculopathy, and they underwent spine injection at the lumbar level. Forty-two patients complained of neck pain with or without cervical radiculopathy, and they received a spine injection at the cervical level. The median interval between the patient visit after injection was 56 days (interquartile range: 73.41–99.34 days).

We found that outcome measurements do not always show concordant response for improvement after spine injection. Residual symptom percentage showed good agreement to global perceived effect while numeric rating scale, Oswestry disability index and neck disability index show poor agreement in patient with either neck or low back pain. The concordance correlation coefficient between the residual symptom percentage and the numeric rating scale was very low, although it had higher concordance in patients with severe pain before the spine injection.




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