Duration of Low Back Pain Does Not Predict Presence of Neuropathic Pain

Time since current pain onset was not a predictor for neuropathic pain among patients with low back pain (LBP), according to the results of a study published in Pain Practice.

Patients with LBP who received treatment at the Yonsei University College of Medicine in South Korea since 2017 met inclusion criteria for this retrospective, cross-sectional study. The duration of LBP symptoms was evaluated as a significant predictor for neuropathic pain, defined as painDETECT score greater than or equal to 13.

The study population included 1957 patients, of whom 255 reported symptoms of neuropathic pain. Patients had a mean (SD) age of 62.1 (15.3) years, a median BMI of 24.2 (IQR, 22.0-26.4) kg/m², and 59.8% were women.

Overall, the mean (SD) numeric rating scale (NRS) score for pain was 6.2 (2.1) points and the median duration of pain was 12.0 (IQR, 4.0-48.0) months. Individuals with neuropathic pain reported higher pain scores (P <.001) but a similar pain duration (P =.695).

Patients were stratified into 5 pain duration groups, ranging from less than 3 months (n=349) to 10 years or more (n=254). No significant differences in painDETECT scores were observed among the groups (P =.307). Similar findings were observed among the 255 patients with neuropathic pain (P =.217).

Significant trends were observed among patients for the outcomes of persistent pain with slight fluctuations (P <.001), persistent pain with pain attacks (P =.002), and pain attacks that involved pain between attacks (P =.003). Persistent pain with slight fluctuations was more common for those with pain with longer-duration and pain between attacks was less common for those with longer-duration pain.

In addition, predictors for neuropathic pain included lumbar surgery (adjusted odds ratio [aOR], 2.614; 95% CI, 1.460-4.679; P =.001), opioid usage (aOR, 2.383; 95% CI, 1.376-4.125; P =.002), maximum NRS pain score (aOR, 2.018; 95% CI, 1.237-3.292; P =.005), sleep disturbance (aOR, 1.729; 95% CI, 1.174-2.547; P =.006), and lumbosacral radiculopathy (aOR, 1.564; 95% CI, 1.021-2.397; P =.040).

Limitations of the study included potential bias as a result of its retrospective design and prior use of analgesics indicated by most patients at their initial visit. Moreover, neuropathic pain was defined using the painDETECT instrument and not clinical examination.

“[D]iagnostic and therapeutic approaches for the neuropathic component of LBP should be based on a multidimensional assessment that considers pain characteristics, surgical history, and comorbidities and not just pain duration,” the study authors concluded.