Placebo and Side Effects Confound Clinical Trials on New Antitussives

Methods to address functional unblinding of raters in CNS trials

Treatment-emergent adverse events (TEAEs) associated with the unique properties of a pharmaceutical product may functionally unblind clinician ratings, obscure true medication effects, and affect confidence about clinical trial results. Central nervous system studies are particularly susceptible to functional unblinding because they rely on relatively subjective symptom assessments. Two different methods were used to examine possible functional unblinding in pooled data from three recent five-week, double-blind, placebo-controlled trials of xanomeline and trospium chloride (formerly known as KarXT) in participants with schizophrenia experiencing acute psychosis. Xanomeline/trospium is an M1/M4 muscarinic receptor agonist that may produce cholinergic side effects. First, we compared the scores of remote (site-independent) raters, blinded to TEAEs, who listened to audio recorded, site-based Positive and Negative Syndrome Scale (PANSS) interviews. Second, we conducted a post hoc analysis of participant subgroups with or without reported cholinergic-related TEAEs to ascertain whether cholinergic TEAEs influenced trial outcome. Remote ratings closely replicated 575 available "paired" site-based PANSS total scores at baseline and endpoint (intraclass correlation coefficient = 0.88 and 0.93, respectively). Both site-based and remote PANSS scores yielded significant improvement favouring xanomeline/trospium over placebo (both p < 0.0001) and yielded significantly greater treatment response (≥30% improvement from baseline) than placebo (both p < 0.0001). The significant improvement of PANSS scores favouring xanomeline/trospium over placebo was comparable in magnitude for all subgroups regardless of whether participants reported cholinergic-related TEAEs, or any TEAEs at all (all p < 0.001). In sum, the two different methods used to assess functional unblinding in these studies found no impact of cholinergic TEAEs, or any TEAEs, on the trial results. These methods may have utility across all clinical trials.

Effects of Remifentanil Pretreatment on Sufentanil-induced Cough Suppression During the Induction of General Anesthesia

PURPOSE

The aim of this study was to evaluate the effect of remifentanil pretreatment on sufentanil-induced cough during general anesthesia induction.

DESIGN

This experimental research was conducted as a single-center, randomized, parallel-group trial.

METHODS

A total of 120 patients scheduled for elective surgery were equally randomized into two groups (remifentanil and control). The incidence and severity of coughing in both groups were recorded after sufentanil administration during general anesthesia induction. The mean arterial pressure, heart rate, and pulse oxygen saturation were recorded at T1 (before the injection of remifentanil or normal saline), T2 (1 minute after remifentanil administration), T3 (before intubation), and T4 (1 minute after intubation). Additionally, the incidences of adverse events, including dizziness, nausea, apnea, truncal rigidity, bradycardia, or other adverse effects were also recorded.

FINDINGS

The incidence of sufentanil-induced cough in the remifentanil group was significantly decreased when compared with the control group (5.0% vs 35.0%, respectively; P < .001). No statistical differences were found in mean arterial pressure, heart rate, pulse oxygen saturation, and the incidences of other side effects between the two groups at T1, T2, T3, and T4 (P > .05).

CONCLUSIONS

Pretreatment with remifentanil at a dose of 0.5 mcg/kg can effectively and safely suppress the incidence and severity of sufentanil-induced coughing, providing a reference for medication during general anesthesia induction.

Adverse Events as a Cause of Unblinding of Allocated Arms in Anti-Amyloid Therapy Trials: A Meta-Analysis of the Predictive Value

Anti-amyloid drugs for early Alzheimer's disease, including lecanemab, are associated with adverse events (AEs), such as amyloid-related imaging abnormalities (ARIA)-edema/effusion (E), ARIA-hemorrhage, and infusion-related reactions, which can indicate allocated arms in clinical trials. Herein, we evaluated the predictive value of AEs using a meta-analysis to estimate their incidence and simulated positive predictive value (PPV). The PPV for ARIA-E was high (0.915), but that for ARIA hemorrhage was low (0.630). Infusion-related reactions had a high PPV of 0.910, but with a wide confidence interval. Our results suggest the need to ameliorate the unblinding effects of AEs, particularly ARIA-E in trials.

Recalibrating the Risk-Benefit Profiles of Lecanemab and Donanemab: Scales, Immunoreactivity, and Changes in Amyloid-β42

Three recent anti-amyloid-β antibody trials for Alzheimer's disease reported similar effect sizes, used non-reactive saline as placebo, and showed large numbers of adverse events including imaging anomalies (ARIA) that correlate with cognitive changes. Conversely, all previous antibody trials were less reactive and pronounced ineffective. We argue that these observations point to unblinding bias, inflating apparent efficacy and thus altering the risk-benefit balance. Further, we highlight data demonstrating that beyond reducing amyloid, monoclonal antibodies increase monomeric amyloid-β42 in cerebrospinal fluid, which may explain potential benefits. We should recalibrate the efficacy of these antibodies and devote more resources into strategies beyond removing amyloid.