The researchers from University of Missouri School of Medicine and MU Health Care compared four drugs with different mechanisms of action in a large group of patients with cryptogenic sensory polyneuropathy (CSPN) to determine which drugs are most useful for this condition. The clinical study involved 40 sites and enrolled 402 patients with diagnosed CSPN who were 30 years or older and reported a pain score of four or greater on a 10-point scale. Participants were prescribed one of four medications commonly used to treat CSPN: nortriptyline, a tricyclic antidepressant; duloxetine, a serotonin-norepinephrine reuptake inhibitor; pregabalin, an anti-seizure drug; or mexiletine, an antiarrhythmic medication. Patients took the prescribed treatment for 12 weeks and were evaluated at four, eight and 12 weeks. Any participant who reported at least a 50% reduction in pain was deemed as demonstrating an efficacious result. Patients who discontinued the treatment drug because of adverse effects were also measured.
Nortriptyline had the highest efficacious percentage (25%), and the second-lowest quit rate (38%), giving it the highest level of overall utility. Duloxetine had the second-highest efficacious rate (23%), and lowest drop-out rate (37%). Pregbalin had the lowest efficacy rate (15%) and Mexiletene had the highest quit rate (58%).
As a result of the four medications, nortriptyline and duloxetine performed better when efficacy and dropouts were both considered.
Patient Assisted Intervention for Neuropathy: Comparison of Treatment in Real Life Situations (PAIN-CONTRoLS)
Cryptogenic sensory polyneuropathy (CSPN) is a common generalized slowly progressive neuropathy, second in prevalence only to diabetic neuropathy. Most patients with CSPN have significant pain. Many medications have been tried for pain reduction in CSPN, including antiepileptics, antidepressants, and sodium channel blockers. There are no comparative studies that identify the most effective medication for pain reduction in CSPN.
To determine which medication (pregabalin, duloxetine, nortriptyline, or mexiletine) is most effective for reducing neuropathic pain and best tolerated in patients with CSPN.
From December 1, 2014, through October 20, 2017, a bayesian adaptive, open-label randomized clinical comparative effectiveness study of pain in 402 participants with CSPN was conducted at 40 neurology care clinics. The trial included response adaptive randomization. Participants were patients with CSPN who were 30 years or older, with a pain score of 4 or greater on a numerical rating scale (range, 0-10, with higher scores indicating a higher level of pain). Participant allocation to 1 of 4 drug groups used the utility function and treatment’s sample size for response adaptation randomization. At each interim analysis, a decision was made to continue enrolling (up to 400 participants) or stop the whole trial for success (80% power). Patient engagement was maintained throughout the trial, which helped guide the study and identify ways to communicate and disseminate information. Analysis was performed from December 11, 2015, to January 19, 2018. Interventions Participants were randomized to receive nortriptyline (n = 134), duloxetine (n = 126), pregabalin (n = 73), or mexiletine (n = 69).
Main Outcomes and Measures
The primary outcome was a utility function that was a composite of the efficacy (participant reported pain reduction of ≥50% from baseline to week 12) and quit (participants who discontinued medication) rates. Results Among the 402 participants (213 men [53.0%]; mean [SD] age, 60.1 [13.4] years; 343 White [85.3%]), the utility function of nortriptyline was 0.81 (95% bayesian credible interval [CrI], 0.69-0.93; 34 of 134 [25.4%] efficacious; and 51 of 134 [38.1%] quit), of duloxetine was 0.80 (95% CrI, 0.68-0.92; 29 of 126 [23.0%] efficacious; and 47 of 126 [37.3%] quit), pregabalin was 0.69 (95% CrI, 0.55-0.84; 11 of 73 [15.1%] efficacious; and 31 of 73 [42.5%] quit), and mexiletine was 0.58 (95% CrI, 0.42-0.75; 14 of 69 [20.3%] efficacious; and 40 of 69 [58.0%] quit). The probability each medication yielded the highest utility was 0.52 for nortriptyline, 0.43 for duloxetine, 0.05 for pregabalin, and 0.00 for mexiletine.
Conclusions and Relevance
This study found that, although there was no clearly superior medication, nortriptyline and duloxetine outperformed pregabalin and mexiletine when pain reduction and undesirable adverse effects are combined to a single end point.