Do Patients Accurately Recall Their Pain Levels Following Epidural Steroid Injection? A Cohort Study of Recall Bias in Patient-Reported Outcomes.

BACKGROUND

Although patient-reported outcomes (PROs) have become important in the evaluation of spine surgery patients, the accuracy of patient recall of pre- or post-intervention  symptoms following epidural steroid injection remains unknown.

OBJECTIVES

The purpose of this study was to: 1) characterize the accuracy of patient recollection of back/leg pain following epidural steroid injection; 2) characterize the direction and magnitude of recall bias; and 3) characterize factors that impact patient recollection.

STUDY DESIGN

A prospective cohort study.

SETTING

Level 1 Academic Medical Center.

METHODS

Using standardized questionnaires, we recorded numeric pain scores for patients undergoing lumbar epidural steroid injections at our institution. Baseline pain scores were obtained prior to injection, 4-hours and 24-hours postinjection. At a minimum of 2 weeks following the injection, patients were asked to recall their symptoms preinjection and at 4 hours and 24-hours postinjection. Actual and recalled scores, at each time point, were compared using paired t tests. Multivariable linear regression was used to identify factors that impacted recollection.

RESULTS

Sixty-one patients with a mean age of 61.4 years (56% women) were included. Compared to their preinjection pain score, patients showed considerable improvement at both 4 hours (Mean Difference [MD] = 2.18, 95% Confidence Interval [CI] 1.42 to 2.94) and 24 hours (MD = 2.64, 95% CI 1.91 to 3.34) postinjection. Patient recollection of preinjection symptoms was significantly more severe than actual at the 2-week time point (MD = 1.39, 95% CI 4.82 to 6.08). The magnitude of recall bias was mild and exceeded the minimal clinically important difference (MCID). No significant recall bias was noted on patient recollection of postinjection symptoms at 4 hours (MD = 0.41, 95% CI -1.05 to 0.23). Patient recollection of symptoms was also significantly more severe than actual at 24 hours (MD = 0.63, 95% CI -1.17 to -0.07), mild magnitude of bias that did not exceed MCID. Linear regression models for differences between actual and recalled pain scores reveal that for recall at 4 hours postinjection, older patients were better at recalling pain.

LIMITATIONS

Baseline pain scores were completed in person, in front of a provider. The short-term pain scores were completed while at home, and then recalled scores were obtained by phone call encounter. Telephone surveys can lead to interview bias. All patients received incentive for completion of study. It is unclear if patient incentives have any impact on patient recall. Patients were contacted 2 weeks postinjection; this time point is standard at our institution, but could vary depending on practice location. Lastly, the enrolled patients did not all share the same indication for injection, and pain was not stratified between back and leg pain.

CONCLUSIONS

Relying on patient recollection does not provide an accurate measure of preinjection status after lumbar epidural steroid injection, although patients did recall their 4-hour postinjection status. These findings support previous studies indicating that relying on patient recollection does not provide an accurate measure of preintervention symptoms. Patient recollection of postintervention symptoms, however, may have some clinical utility and requires further study.