Ching-Ray Yu

The Fagerström Test for Nicotine Dependence as a Predictor of Smoking Abstinence: A Pooled Analysis of Varenicline Clinical Trial Data

INTRODUCTION We explored the relationship between the Fagerström Test for Nicotine Dependence (FTND) and smoking abstinence rates in 10 randomized, double-blind placebo-controlled Phase 2-4 varenicline studies. METHODS Participants were adult smokers (≥10 cigarettes/day) who were motivated to quit. Efficacy end points included continuous abstinence rate (CAR) for weeks 9-24 analyzed, by baseline FTND and Heaviness of Smoking Index (HSI) scores, and treatment. Data were analyzed using logistic regression models. RESULTS Overall, 2,763 varenicline (M [SD] FTND score: 5.6 [2.2]) and 2,229 placebo subjects (5.5 [2.1]) were included in the analysis. An increase of one unit in baseline FTND or HSI score decreased the odds of abstinence at Week 24 by 11% (odds ratio [OR] 0.89, 95% CI 0.86-0.92, p < .0001) and 18% (OR 0.82, 95% CI 0.79-0.87, p < .0001), respectively. Treatment had a significant impact on CAR 9-24: odds of abstinence were increased threefold for varenicline versus placebo (OR 3.3, 95% CI 2.8-3.8, p < .0001). There was no interaction between treatment and FTND (p = .98) or HSI score (p = .97) for CAR 9-24. The HSI score predicted abstinence outcome as effectively as the FTND score. CONCLUSION Abstinence rates decreased with increasing dependence scores. There was no interaction between treatment and baseline FTND or HSI score, suggesting that they have no effect on the efficacy of varenicline versus placebo. These results also suggest that the HSI may be as effective at predicting smoking cessation outcome as the whole FTND questionnaire.

Effect of Varenicline on Smoking Cessation Through Smoking Reduction: A Randomized Clinical Trial

IMPORTANCE Some cigarette smokers may not be ready to quit immediately but may be willing to reduce cigarette consumption with the goal of quitting. OBJECTIVE To determine the efficacy and safety of varenicline for increasing smoking abstinence rates through smoking reduction. DESIGN, SETTING, AND PARTICIPANTS Randomized, double-blind, placebo-controlled, multinational clinical trial with a 24-week treatment period and 28-week follow-up conducted between July 2011 and July 2013 at 61 centers in 10 countries. The 1510 participants were cigarette smokers who were not willing or able to quit smoking within the next month but willing to reduce smoking and make a quit attempt within the next 3 months. Participants were recruited through advertising. INTERVENTIONS Twenty-four weeks of varenicline titrated to 1 mg twice daily or placebo with a reduction target of 50% or more in number of cigarettes smoked by 4 weeks, 75% or more by 8 weeks, and a quit attempt by 12 weeks. MAIN OUTCOMES AND MEASURES Primary efficacy end point was carbon monoxide-confirmed self-reported abstinence during weeks 15 through 24. Secondary outcomes were carbon monoxide-confirmed self-reported abstinence for weeks 21 through 24 and weeks 21 through 52. RESULTS The varenicline group (n = 760) had significantly higher continuous abstinence rates during weeks 15 through 24 vs the placebo group (n = 750) (32.1% for the varenicline group vs 6.9% for the placebo group; risk difference (RD), 25.2% [95% CI, 21.4%-29.0%]; relative risk (RR), 4.6 [95% CI, 3.5-6.1]). The varenicline group had significantly higher continuous abstinence rates vs the placebo group during weeks 21 through 24 (37.8% for the varenicline group vs 12.5% for the placebo group; RD, 25.2% [95% CI, 21.1%-29.4%]; RR, 3.0 [95% CI, 2.4-3.7]) and weeks 21 through 52 (27.0% for the varenicline group vs 9.9% for the placebo group; RD, 17.1% [95% CI, 13.3%-20.9%]; RR, 2.7 [95% CI, 2.1-3.5]). Serious adverse events occurred in 3.7% of the varenicline group and 2.2% of the placebo group (P = .07). CONCLUSIONS AND RELEVANCE Among cigarette smokers not willing or able to quit within the next month but willing to reduce cigarette consumption and make a quit attempt at 3 months, use of varenicline for 24 weeks compared with placebo significantly increased smoking cessation rates at the end of treatment, and also at 1 year. Varenicline offers a treatment option for smokers whose needs are not addressed by clinical guidelines recommending abrupt smoking cessation. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01370356.

Effect of varenicline on individual nicotine withdrawal symptoms: a combined analysis of eight randomized, placebo-controlled trials.

INTRODUCTION Concerns exist that varenicline may cause neuropsychiatric side effects. Some of these symptoms (e.g., depression, irritability) have been measured in clinical trials using nicotine withdrawal scales. This study assessed the effect of varenicline on neuropsychiatric and other symptoms, as measured by the Minnesota Nicotine Withdrawal Scale (MNWS). METHODS We analyzed weekly individual MNWS symptom ratings in 8 randomized double-blind, placebo-controlled smoking cessation trials funded by Pfizer with similar methodology (n = 2,403 varenicline; n = 1,434 placebo). Ratings for the past 24hr were obtained prior to quitting and starting treatment and at Weeks 1-6 and 11 after the quit date. RESULTS In repeated measures analyses controlling for baseline values, ratings for 5 neuropsychiatric symptoms (depressed mood, irritability, anxiety, difficulty concentrating, and restlessness) and urge to smoke were lower (p < .01) for varenicline than placebo at each timepoint. Worsening in scores from 0-2 (baseline) to 4 was less frequent on varenicline than placebo for all ratings except appetite- (significantly more frequent for varenicline, p < .0001) and sleep-related items. Repeated measures analysis for individuals with low levels of exhaled carbon monoxide revealed similar patterns except for a nonsignificant difference for increased appetite. CONCLUSIONS Use of varenicline while trying to quit smoking reduces and does not increase neuropsychiatric symptoms such as depressed mood and irritability measured on the MNWS in smokers without current psychiatric disorders. It is associated with increases in sleep disturbance and appetite although the latter appears due to enabling more subjects to abstain from smoking.

Generalized Estimation of the BLUP in Mixed-Effects Models: A Comparison with ML and REML

The Best Linear Unbiased Predictor (BLUP) in mixed models is a function of the variance components and they are estimated using maximum likelihood (ML) or restricted ML methods. Nonconvergence of BLUP would occur due to a drawback of the standard likelihood-based approaches. In such situations, ML and REML either do not provide any BLUPs or all become equal. To overcome this drawback, we provide a generalized estimate (GE) of BLUP that does not suffer from the problem of negative or zero variance components, and compare its performance against the ML and REML estimates of BLUP. Simulated and published data are used to compare BLUP.

Comparison of adjustment methods for stratified two-sample tests in the context of ROC analysis.

We compare several nonparametric and parametric weighting methods for the adjustment of the effect of strata. In particular, we focus on the adjustment methods in the context of receiver-operating characteristic (ROC) analysis. Nonparametrically, rank-based van Elterens test and inverse-variance (IV) weighting using the area under the ROC curve (AUC) are examined. Parametrically, the stratified t-test and IV AUC weighted method are applied based on a binormal monotone transformation model. Stratum-specific, pooled, and adjusted estimates are obtained. The pooled and adjusted AUCs are estimated. We illustrate and compare these weighting methods on a multi-center diagnostic trial and through extensive Monte-Carlo simulations.

In vivo measurement of PDE10A enzyme occupancy by positron emission tomography (PET) following single oral dose administration of PF-02545920 in healthy male subjects.

&NA; Phosphodiesterase 10A (PDE10A) is an enzyme highly enriched in the striatal medium spiny neurons. It is involved in the regulation of cytoplasmic levels of cAMP and cGMP and signaling within the basal ganglia. This study with PDE10A radioligand [18F]MNI‐659 was designed to measure the enzyme occupancy of PF‐02545920 in 8 healthy male volunteers (48 ± 4 years) after a single oral dose (10 mg or 20 mg) and to evaluate safety and tolerability. Arterial blood sampling was performed to obtain a metabolite‐corrected plasma input function for the quantification of [18F]MNI‐659 binding to PDE10A. The occupancy of PF‐02545920 was calculated with two different methods: In Method 1, [18F]MNI‐659 enzyme occupancy was calculated from the estimates of binding potential, using the cerebellum as a reference region; in Method 2, occupancy was estimated from the slope of the revised Lassens plot. Serum concentrations of PF‐02545920 were measured to determine the relationship between concentration and occupancy. Based on Method 1, striatal PDE10A occupancy increased with increasing PF‐02545920 dose: 14–27% at 10 mg dose (N = 4) and 45–63% at 20 mg dose (N = 3). Comparable occupancies were observed using Lassens plot Method 2: 10 mg: 14–37%; 20 mg: 46–55%. The relationship between exposure and occupancy was best described using an Emax model. The serum concentration associated with 50% occupancy was estimated to be 93.2 ng/mL. Single oral doses of 10 mg or 20 mg of PF‐02545920 were safe and well tolerated in healthy male volunteers [NCT# 01918202]. HighlightsSingle oral doses (10 mg, 20 mg) of PF‐02545920 were safe and well tolerated in healthy male volunteers.Enzyme occupancy of PF‐02545920 obtained using [18F]MNI‐659 PET was in the expected range.Striatal PDE10A occupancy increased with increasing PF‐02545920 dose and exposure, reaching ˜50% following the 20 mg single dose.A 20 mg oral dose of PF‐02545920 provides sufficient target brain occupancy for evaluation in future PDE10 clinical trials.

A comparison of nonparametric and parametric methods to adjust for baseline measures

When analyzing the randomized controlled trial, we may employ various statistical methods to adjust for baseline measures. Depending on the method chosen to adjust for baseline measures, inferential results can vary. We investigate the Type 1 error and statistical power of tests comparing treatment outcomes based on parametric and nonparametic methods. We also explore the increasing levels of correlation between baseline and changes from the baseline, with or without underlying normality. These methods are illustrated and compared via simulations.

Estimating the proportion of differentially expressed genes in comparative DNA microarray experiments

DNA microarray experiments, a well-established experimental technique, aim at understanding the function of genes in some biological processes. One of the most common experiments in functional genomics research is to compare two groups of microarray data to determine which genes are differentially expressed. In this paper, we propose a methodology to estimate the proportion of differentially expressed genes in such experiments. We study the performance of our method in a simulation study where we compare it to other standard methods. Finally we compare the methods in real data from two toxicology experiments with mice.

Efficacy of Varenicline for Cigarette Reduction Before Quitting in Japanese Smokers: A Subpopulation Analysis of the Reduce to Quit Trial

PURPOSE This prospective analysis of the Japanese subpopulation of the varenicline reduce to quit study was conducted to evaluate whether results for Japanese participants were consistent with the full study population. METHODS Patients received varenicline or placebo for a 24-week treatment period (12-week smoking reduction phase then a 12-week smoking abstinence phase) followed by a 28-week nontreatment, follow-up phase. Participants were to reduce the daily number of cigarettes smoked by at least 50% by week 4 and by a further 50% by week 8, with the goal of achieving complete abstinence by week 12. The primary efficacy end point was the carbon monoxide-confirmed continuous abstinence during weeks 15 to 24. FINDINGS Overall, 210 Japanese patients were randomly assigned to 1 of the 2 study groups (varenicline, 107; placebo, 103). Continuous abstinence rates for weeks 15 to 24 were higher for participants in the varenicline group versus the placebo group (46.7% vs 12.6%; odds ratio = 14.68; 95% CI, 5.38-40.05), and the 7-day point prevalence of abstinence rates were higher for varenicline versus placebo at week 12 (odds ratio = 13.76; 95% CI, 5.28-35.86). The number of participants with a ≥50% reduction in the number of daily cigarettes smoked from baseline to week 4 and a ≥75% reduction by week 8 was greater in the varenicline group versus the placebo group (week 4: 59.8% vs 30.1%; week 8: 38.3% vs 12.6%). Serious adverse events were reported in 3.7% of varenicline participants and 1.0% of placebo participants. IMPLICATIONS The efficacy and tolerability results of this analysis are consistent with those of the full varenicline reduce to quit study. Varenicline treatment and cigarette reduction before quitting may provide an alternative approach to smoking cessation in Japanese smokers who are not ready to quit immediately. ClinicalTrials.gov identifier: NCT01370356.

Comparative Effectiveness Research Using Meta-Analysis to Evaluate and Summarize Diagnostic Accuracy

According to the Agency for Healthcare Research and Quality, “comparative effectiveness research is designed to inform health-care decisions by providing evidence on the effectiveness, benefits, and harms of different treatment options. The evidence is generated from research studies that compare drugs, medical devices, tests, surgeries, or ways to deliver health care.” Since it is difficult to systematically review each study to generate the best evidence and practice based on the overall diagnostic accuracy, it is useful to conduct a meta-analysis of such studies. Our main aim is to synthesize and to combine studies that yield proportions in a two-sample setting according to a reference standard. Statistical methods for combining sensitivities, specificities, and log diagnostic odds ratios are compared. A summary receiver operating characteristic curve is constructed. Monte Carlo simulation studies are conducted under both homogeneity and heterogeneity assumptions. For illustration purposes, a publically available example in urology is provided.