Number of Waddell Signs Correlate With Steroid Injection Treatment Failure

The number of Waddell signs present can be indicative of treatment failure, but not of pain score reduction. These findings, from a prospective cohort study, were published in Anesthesia Analgesia.

Patients (n=308) treated at 11 centers in the United States and Germany who received epidural steroid injections (ESI; n=150), facet interventions (n=95), or sacroiliac joint (SIJ; n=63) injections were recruited. All patients had more than 6 weeks of treatment for radicular or non-neuropathic lower back pain within the past 2 years. Patients were assessed at baseline and 1 month for Waddell signs and by the numerical rating scale-pain intensity (NRS-PI), and those who had positive outcomes continued treatment.

At baseline, no Waddell signs were observed among 62% of patients; 1 sign was observed among 18%, 11% had 2 signs, 5% had 3 signs, 2% had 4 signs, and 2% had all 5 Waddell signs. Patients with differing numbers of Waddell signs varied significantly by sex (P =.004), opioid use (P <.001), proportion with worker’s compensation (P <.001), number of coexisting chronic pain conditions (P =.013), presence of multiple psychiatric conditions (P <.001), and baseline pain scores (P £.009).

Stratified by Waddell signs, the mean change in average NRS-PI scores was -1.6 (±2.6), -1.1 (±2.7), -1.5 (±2.5), -1.6 (±2.6), -1 (±1.5), and 0.7 (±2.1) for 0 to 5 signs, respectively. Patients with more Waddell signs exhibited smaller decreases of NRS-PI scores (coefficient, 0.19; 95% CI, -0.43 to 0.05; P =.12), however, this change was not significant.

Compared with patients without Waddell signs, those who experienced nonanatomic tenderness reported less reduction of worst leg pain (0.9±1.9 vs 2.6±3.0; P =.008) and a greater reduction of average leg pain (0.4±2.2 vs 1.7±2.6; P =.028). Those who responded to sham stimulation had a significant decrease in the worst leg pain (1.5±2.4 vs 2.7±3.1; P =.013).

As the number of Waddell signs increased, so did the likelihood of treatment failure (odds ratio [OR], 1.35; 95% CI, 1.08-1.68; P =.008).

A total of 18 complications were observed during the study duration, including 6 patients who reported increased pain symptoms, 4 temporary neurological symptoms, 3 in the ESI group with wet tap or intradiscal injections, 3 neuropsychiatric symptoms, and 2 vasovagal episodes. These observed adverse events did not correlate with Waddell signs (P =.49).

The major limitation of this study is that Waddell signs were measured by a single practitioner using multiple tests grouped by category, therefore, intraobserver error could not be calculated or assessed.

“While this study found no consistent relationship between Waddell signs and decreased mean pain scores, a significant relationship between the number of Waddell signs and treatment failure was observed, which may have treatment implications, the researchers concluded.

Further exploration into combining Waddell signs with other metrics is needed for the better stratification of patients.

Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Cohen SP, Doshi TL, Kurihara C, et al. Waddell (nonorganic) signs and their association with interventional treatment outcomes for low back pain. Published online July 16, 2020. Anesth Analg. doi: 10.1213/ANE.0000000000005054