N-of-1 Randomized Trials of Ultra-Micronized Palmitoylethanolamide in Older Patients with Chronic Pain

Background: Ultra-micronized palmitoylethanolamide (um-PEA) represents an attractive option for chronic pain control in complex older patients at higher risk of adverse effects with traditional analgesics. Objective: The aim of this study was to determine the effectiveness of um-PEA versus placebo on chronic pain intensity and function in individual geriatric patients. Design: We performed randomized, blinded N-of-1 trials with two 3-week um-PEA versus placebo comparisons, separated by 2-week washout periods. Participants: The study included outpatients aged ≥ 65 years with chronic, non-cancer, non-ischemic pain in the back, joints, or limbs. Intervention: Patients were randomized to Um-PEA 600 mg or placebo twice daily. Measurements: Pain intensity was measured using an 11-point visual numeric scale. Functional impairment was measured using a Back Pain Functional Scale. Impact of each N-of-1 trial was measured on the clinician’s intention to treat and confidence. Results: Ten of 11 eligible patients consented over 7 months [all female, mean age 83.2 years (SD 4.6)]. Three patients interrupted the trial: one had diarrhea (under placebo), one for low adherence, and one for intercurrent pneumonia. A small statistically significant effect in favor of um-PEA was seen at the mixed method analyses in two patients (effect size equal to 8% of the baseline pain). A statistically significant impact on function was found in one patient. After the trial, um-PEA was prescribed to four patients; in two patients the clinician changed their pre-trial intention to treat; the clinician confidence in the treatment plan either increased (5) or remained the same (2). Conclusions: Our experience confirmed that N-of-1 trials may help make personalized evidence-based decisions in complex older patients, with special feasibility considerations. ClinicalTrials.gov: NCT02699281.