Background: Although much prescribed, the class of neurotrophic/antinociceptive nutraceuticals, is generally supported by relatively few controlled trials. Looking into the existent literature, we came across an old registration study about micronized palmitoylethanolamide (PEA) in patients with low back pain – sciatica.
Methods: We contacted the producers and obtained all the original material, which allowed us to re-analyze the study. We assessed the clinical relevance by calculating numbers-needed-to treat of pain (visual analog scale) and function (Roland-Morris Questionnaire). After excluding patients with insufficient information, we assigned each patient to one of five categories of increasing probability of neuropathic pain: pure lumbago, lumbago with projected pain to near territories (e.g. gluteus or groin), lumbago with projected pain to the thigh or leg, pure sciatica, and radiculopathy, and correlated (Spearman) the improvement in pain and function with these five classes.
Results: We found the following NNTs (with 95% confidence intervals): PEA 600 mg/die vs. placebo scored an NNT of 1.7 (1.4-2) for the effect on pain and 1.5 (1.4-1.7) for the effect on function. The correlation between the five categories was highly significant for pain relief (P <0.0001), though not significant for reduction of dysfunction.
Conclusions: PEA was extremely efficacious on pain and function in a large cohort of patients with low back pain – sciatica. Although multiple mechanisms of action of PEA are ideal for mixed pain conditions such as low back pain – sciatica, the correlation between pain relief and the likelihood of neuropathic pain suggests a stronger action on the neuropathic pain component.