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PubMed1994

The early termination of clinical trials: causes, consequences, and control. With special reference to trials in the field of arrhythmias and sudden death. Task Force of the Working Group on Arrhythmias of the European Society of Cardiology.

The early termination of clinical trials, for either benefit or harm, often generates undue enthusiasm or alarm. The enhanced publicity attending early termination of a trial promotes inappropriate interpretations that are favored by the inherent difficulty of prompt and comprehensive data review. Furthermore, the process of monitoring the accumulating outcome data for early evidence of treatment benefit or harm is fraught with many statistical and methodological difficulties. This report from a task force convened by the Working Group on Arrhythmias of the European Society of Cardiology incorporates first, a series of trials terminated appropriately or inappropriately for benefit or harm and used as examples to illustrate the importance of suitable trial design and of proper stopping rules; second, a description of the committee structure of a clinical trial; third, an analysis of the general design issues; fourth, a review of the main issues in interim analysis with special reference to main strategies for reducing the rate of false-positive claims that could result from early trial termination; and finally, a series of specific recommendations concerning the design, structure, analysis, interpretation, and presentation of a clinical trial.

Arrhythmias, Cardiac↗
PubMed2006

A tale of two trials: a comparison of the post-acute coronary syndrome lipid-lowering trials A to Z and PROVE IT-TIMI 22.

BACKGROUND: The Aggrastat to Zocor (A to Z) and Pravastatin or Atorvastatin Evaluation and Infection Therapy (PROVE IT) trials compared intensive and moderate statin therapy after acute coronary syndromes, with seemingly disparate results. We analyzed the design, implementation, and results of the two trials in an attempt to clarify the effects of early intensive statin therapy. METHODS AND RESULTS: Study design, end points, and definitions were compared. In each trial, comparisons were made between intensive and moderate arms for both trials' primary end points and death/myocardial infarction. Analyses were performed over various time points: at the end of the trials, < or =4 months, and >4 months. Subjects in A to Z had higher-risk demographics. More PROVE IT subjects were enrolled in the United States and underwent prerandomization revascularization. The low-density lipoprotein (LDL) difference was greater in A to Z than in PROVE IT early (< or =4 months) but less late. Significant C-reactive protein reduction was earlier in PROVE IT. With common end points, event rates were higher in A to Z, and early favorable separation of event curves was seen in PROVE IT but not in A to Z. Clinical end point rates and reductions were similar in both trials after 4 months. CONCLUSIONS: An early benefit was seen in PROVE IT but not in A to Z. Late-phase results were similar. Factors that may explain this disparity include the intensity of therapy in the early phase, timing, and magnitude of LDL and C-reactive protein lowering, differences in early revascularization, and the play of chance. Taken together, the results of these trials support a strategy of early intensive statin therapy coupled with revascularization when appropriate in patients after acute coronary syndrome.

Aged↗
PubMed2005

Adolescents and HIV vaccine trials: what are the clinical trial site issues?

Adolescents worldwide are at high risk for HIV, which makes them essential candidates for HIV vaccine trials. However, enrollment of adolescents into such trials has implications for trial sites. Adolescents are considered vulnerable subjects and require proxy consent in addition to their assent, which brings issues of confidentiality and access into play. HIV vaccine trial sites often do not have experience recruiting and retaining adolescents, and creating youth-friendly environments that are comfortable for guardians. This includes development of education materials that target both youth and their parents. Because these trials are of minimal individual benefit, sites will likely need to provide service in the form of health care and supportive structures to adolescents. Finally, a number of trial design options exist, and researchers will need to balance the risks and benefits of each, as for all issues surrounding the involvement of adolescents in HIV vaccine trials.

AIDS Vaccines↗
PubMed2002

Factors affecting workload of cancer clinical trials: results of a multicenter study of the National Cancer Institute of Canada Clinical Trials Group.

PURPOSE: Increasingly, cancer treatment centers need to be able to estimate specific costs and resources associated with clinical trials. Because the time requirements of trial coordination and data collection are not well known, the Clinical Research Associates (CRA) Committee of the National Cancer Institute of Canada Clinical Trials Group carried out a multicenter study to measure trials' task times and evaluate the effects of certain factors. METHODS: A data collection instrument was designed and validated before its implementation in the study. Eighty-three CRAs from 24 cancer treatment institutions across Canada collected timing observations of 41 tasks (156 subtasks). Information from all stages of trials activity (protocol management, eligibility and entry, treatment, and follow-up and final stage) was obtained, from initial negotiations to follow-up after study closure. RESULTS: After controlling for stage, phase and sponsor were found to be significant independent factors. Analysis within the stages showed similar patterns. New drug inclusion as a factor was confounded with phase. Industry-sponsored studies had significantly higher overall mean times than did local and cooperative group studies. Early-phase studies required more time than did phase III trials. External sponsorship of any kind increased CRA time more than that necessary for locally coordinated studies, except during the protocol management stage. The burden of a phase I study increased to greater than average once underway and accruing patients. CONCLUSION: Our data demonstrated that sponsor and study phase are important factors to be taken into consideration when estimating clinical trial costs and resource use.

Cancer Care Facilities↗
PubMed2001

Does intention-to-treat analysis answer all questions in long-term mortality trials? Considerations on the basis of the ANZ trial.

AIMS: Intention-to-treat (ITT) analyses are the gold standard in endpoint analyses of randomized clinical trials. Valuable information, however, may be lost in this approach as the actual time on trial medication is not accounted for in patients who withdraw early. Since compliance per se can be a prognostic factor and the actual treatment time is a variable likely to influence clinical outcome, this information should be added to an ITT analysis concept. Thus, the aim is to elucidate the influence of actual treatment time on the results of ITT analysis using available data from a well-conducted, large-scale clinical trial. METHODS AND RESULTS: The ANZ trial, a carvedilol study in heart failure, is characterized by a considerable number of early withdrawals in the carvedilol group. Using the ANZ trial database, the percentage of withdrawals was calculated as well as the number of days on treatment. Fourteen out of 21 deaths (67%) in the carvedilol group occurred after discontinuation of carvedilol. At the time of death, 14 out of 29 (48%) patients in the placebo group had withdrawn from treatment. Mean time of patients on medication who withdrew and died later were 301 days for placebo, but only 204 days for carvedilol. We performed a conventional ITT analysis, and an ITT-based Cox-proportional hazards model (modified ITT) in which the actual time on trial medication was entered into the model as an explanatory variable. The risk ratio in conventional ITT analysis was 0.71 (95% confidence interval (CI) 0.41 to 1.24, p = 0.228) and 0.50 (95% CI 0.28-0.90, p < 0.001 ) in modified ITT analysis. CONCLUSIONS: Incorporation of the actual treatment time substantially influences the result of this exemplary ITT analysis. The resulting risk ratio is clearly in accordance with clinical implications and in close agreement with those of other beta-blocker trials in heart failure. Entering the actual treatment time into a Cox-proportional hazards model as an explanatory variable is reasonable if not necessary from a clinical point of view and thus may strengthen the validity of ITT analysis.

Aged↗
PubMed1995

Comparison of health-related quality of life in clinical trial and nonclinical trial human immunodeficiency virus-infected cohorts.

Clinical trials randomly assign treatments and select participants to maximize internal validity, but such selection threatens generalizability by excluding important groups with the diseases under study. Particularly in human immunodeficiency virus (HIV) disease, the results of clinical trials are applied broadly to populations, despite limited representation by minorities and disadvantaged groups. Health-related quality of life (HRQOL), which is increasingly recognized as an important outcome in these studies, may be sensitive to differences that affect generalization of trial results to target populations. This study compared HRQOL in two HIV-infected cohorts: 1) multicenter AIDS Clinical Group Trials in which most subjects are white, privately insured, and high-income (n = 1,907); and 2) a study of ethnically diverse, low-income patients recruited from public clinics (n = 205). Both studies included 30 HRQOL items developed in the Medical Outcomes Study (MOS) and items on symptoms, medications, and demographic characteristics. HRQOL scores were significantly lower in the nontrial sample (P < 0.001) by about one standard deviation, even after direct adjustment for clinical and demographic characteristics, and also after comparison of the nontrial sample with the most symptomatic in the trial sample. The relationships of characteristics with HRQOL differed between nontrial and trial samples, suggesting problems generalizing results from HIV clinical trials to important target populations. HRQOL measures such as those from the MOS can be useful in detecting differences that affect generalization.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Preparations for HIV vaccine trials: moving from baseline studies to efficacy trials.

In summary, much has been accomplished in the past year, but much still remains to be done before we can embark on an efficacy trial. With the availability of a fully operational network, the NIAID has in place the resources and mechanisms to complete baseline feasibility studies and to conduct the future trials. As presented at the 1993 conference and reported in this supplement, the preliminary data from the current baseline studies indicate that such trials are feasible, although not without considerable problems. To reach our "efficacy trials preparedness" goal, we will need to work especially hard in the coming months to identify and resolve the remaining technical, ethical, legal, and political constraints to initiating trials. We must also listen to community concerns and educate the public about the trials if we expect to gain community support and volunteers for the study. Finally, we must evaluate the supporting data pertaining to candidate products for efficacy trials. These will not be easy tasks or decisions, but we must approach them with vigor.

AIDS Vaccines↗
PubMed1998

Italian Breast Cancer Adjuvant Chemo-Hormone Therapy Cooperative Group Trials. GROCTA Trials.

The first GROCTA trial compared 5-year tamoxifen treatment to ten chemotherapy cycles in a group of 504 pre-/post-menopausal, node-positive, ER-positive breast cancer patients. This study also included an arm combining tamoxifen with chemotherapy. Fifteen-year results showed no difference between tamoxifen and tamoxifen plus chemotherapy, while both treatments were significantly superior to chemotherapy alone. A confirmatory study (GROCTA 02) was performed in 244 pre-/perimenopausal patients by comparing 5 years of tamoxifen treatment (plus 2 years of goserelin) to six CMF cycles. No difference has emerged so far between the tamoxifen and CMF arms at a median follow-up time of 62 months. Post-menopausal women were scheduled to receive 3 years of tamoxifen treatment and then to be randomly allocated to further 2 years of tamoxifen or to 2 years of low-dose aminoglutethimide (GROCTA 04B). So far 662 patients have been entered, 375 of whom have been randomized to tamoxifen (n = 188) or aminoglutethimide (n = 187). Preliminary results (median follow-up time 32 months) show no major difference in patients' outcome. A new trial (ITA trial) with a similar design but employing anastrozole in place of aminoglutethimide has been activated in 1998. The GROCTA 03 study investigated the potential superiority of alternating adjuvant chemotherapy over standard CMF. This study, which included 107 node-positive ER-negative pre-menopausal women, was prematurely closed because more patients allocated to the triple alternated chemotherapy appeared to have relapsed and died at the first interim analysis. The use of high-dose chemotherapy (HDC) was explored by the GROCTA 06 trial which included 53 patients with ten or more involved nodes and a maximum age of 55 years. These patients were scheduled to receive three standard CEF cycles followed by one cycle of HDC (cyclophosphamide 5 g/m2; etoposide 1.5 g/m2; cisplatin 150 mg/m2) without any form of bone marrow rescue. This HDC program proved to be feasible but was not superior to CMF-based chemotherapy we had previously employed in a comparable group of patients in previous GROCTA trials. These findings prompted us to explore new HDC programmes with the use of peripheral stem cell support and in addition the possible value of new drugs such as Taxol and vinorelbine. New-generation trials will also explore the value of new prognostic indicators such as tumor proliferative activity, which are prospectively used to allocate patients to different treatment options.

Antineoplastic Agents, Hormonal↗
PubMed1995

Problems and suggested solutions in creating an archive of clinical trials data to permit later meta-analysis: an example of methotrexate trials in rheumatoid arthritis.

Because data archives contain patient-based rather than study-based data, they can address meta-analytic questions on uncommon outcomes and on predefined patient subsets, questions that are difficult to address using the traditional meta-analytic approach based on grouped data. We report the tasks involved in establishing the first data archive of rheumatoid arthritis trials. In general, problems stem from the heterogeneity of trials in the archive and we suggest some solutions. In the initial phases, difficulties include recruitment and incomplete participation of trial investigators, whereas later on, other issues arise, such as quality control, coping with different dataset designs, and incomplete documentation. Other issues include heterogeneous measures, missing variables, and comparing data across different visit intervals and trial lengths. Suggested solutions include requesting trial data in predefined archive-wide structures and asking for all possible documentation for each dataset. Data cleaning is necessary, as is rescaling of variables or developing unit-free outcomes, and estimating data for missing variables. Archive design should allow for referencing a patient's data among various datasets. Although one goal is to reduce the quantity of data in the archive while retaining information content, data from early stages of archive building must be accessible for developing new analysis datasets. Documentation of archive building and software choices are discussed. Our experience suggests data archiving for meta-analysis is time consuming and expensive, yet it provides a useful method for analyzing data from multiple trials.

Archives↗
PubMed1984

Beta-blocker heart attack trial: design, methods, and baseline results. Beta-blocker heart attack trial research group.

The Beta-Blocker Heart Attack Trial (BHAT) was a multicentered, double-blind, randomized, placebo-controlled clinical trial designed to test the efficacy of long-term therapy with propranolol given to survivors of an acute myocardial infarction (MI). Three thousand, eight hundred and thirty-seven men and women, aged 30-69 years, were randomized into either the propranolol or placebo group 5 to 21 days after hospital admission for the MI and were followed at quarterly visits for 12 to 40 months (mean = 25 months). The primary outcome for the trial was all-cause mortality. This article describes the design and baseline findings of the trial. Included is a description of the historical background for the trial and the procedures employed in patient recruitment, randomization, treatment and follow-up. Also included is a comparison between the BHAT population and post-myocardial infarction patients enrolled in the other long-term trials of beta-blockers.

Adrenergic beta-Antagonists↗
PubMed2001

Challenges of subgroup analyses in multinational clinical trials: experiences from the MERIT-HF trial.

BACKGROUND: International placebo-controlled survival trials (Metoprolol Controlled-Release Randomised Intervention Trial in Heart Failure [MERIT-HF], Cardiac Insufficiency Bisoprolol Study [CIBIS-II], and Carvedilol Prospective Randomized Cumulative Survival trial [COPERNICUS]) evaluating the effects of b-blockade in patients with heart failure have all demonstrated highly significant positive effects on total mortality as well as total mortality plus all-cause hospitalization. Also, the analysis of the US Carvedilol Program indicated an effect on these end points. Although none of these trials are large enough to provide definitive results in any particular subgroup, it is natural for physicians to examine the consistency of results across various subgroups or risk groups. Our purpose was to examine both predefined and post hoc subgroups in the MERIT-HF trial to provide guidance as to whether any subgroup is at increased risk, despite an overall strongly positive effect, and to discuss the difficulties and limitations in conducting such subgroup analyses. METHODS: The study was conducted at 313 clinical sites in 16 randomization regions across 14 countries, with a total of 3991 patients. Total mortality (first primary end point) and total mortality plus all-cause hospitalization (second primary end point) were analyzed on a time to first event. The first secondary end point was total mortality plus hospitalization for heart failure. RESULTS: Overall, MERIT-HF demonstrated a hazard ratio of 0.66 for total mortality and 0.81 for mortality plus all-cause hospitalization. The hazard ratio of the first secondary end point of mortality plus hospitalization for heart failure was 0.69. The results were remarkably consistent for both primary outcomes and the first secondary outcome across all predefined subgroups as well as for nearly all post hoc subgroups. The results of the post hoc US subgroup showed a mortality hazard ratio of 1.05. However, the US results regarding both the second primary combined outcome of total mortality plus all-cause hospitalization and of the first secondary combined outcome of total mortality plus heart failure hospitalization were in concordance with the overall results of MERIT-HF. Tests of country by treatment interaction (14 countries) revealed a nonsignificant P value of.22 for total mortality. The mortality hazard ratio for US patients in New York Heart Association (NYHA) class III/IV was 0.80, and it was 2.24 for patients in NYHA class II, which is not consistent with causality by biologic gradient. We have not been able to identify any confounding factor in baseline characteristics, baseline treatment, or treatment during follow-up that could account for any treatment by country interaction. Thus we attribute the US subgroup mortality hazard ratio to be due to chance. CONCLUSIONS: Just as we must be extremely cautious in overinterpreting positive effects in subgroups, even those that are predefined, we must also be cautious in focusing on subgroups with an apparent neutral or negative trend. We should examine subgroups to obtain a general sense of consistency, which is clearly the case in MERIT-HF. We should expect some variation of the treatment effect around the overall estimate as we examine a large number of subgroups because of small sample size in subgroups and chance. Thus the best estimate of the treatment effect on total mortality for any subgroup is the estimate of the hazard ratio for the overall trial.

Adrenergic beta-Antagonists↗
PubMed2003

Update on progress in the international, multicenter, randomized, controlled trial of corticosteroids after significant head injury (Medical Research Council CRASH Trial).

PURPOSE OF REVIEW: To provide an update on the progress of the multicenter, randomized, controlled trial of corticosteroids after significant head injury (CRASH). RECENT FINDINGS: After a successful pilot phase, the main phase of the CRASH Trial began in March 2001. By June 2002, 107 hospitals from 31 countries were participating in the trial, and together had recruited 3000 patients. Nine hundred patients (30%) had mild head injury, 885 (30%) had moderate head injury, and 1215 (40%) had severe head injury. A total of 1941 (65%) patients were randomized within 3 hours of injury. Outcome at 2 weeks from injury was known for 2933 (98%) patients, of whom 557 (19%) died. At the time of writing, 6-month follow-up for the first 1500 patients was nearly complete. Vital status was known for 1429 (95%) of the 1500 patients, of whom 313 (22%) had died. Functional status based on the Glasgow Outcome Scale was known for 1391 (93%) of the 1500 patients: 22% were dead, 16% were severely disabled, 23% were moderately disabled, and 39% had made a good recovery. SUMMARY: The CRASH Trial is a randomized, placebo-controlled, multicenter trial of a 48-hour corticosteroid infusion after significant head injury and is now the largest head injury trial ever conducted. The efforts of the national coordinators have shown that it is possible to enroll and follow up very large numbers of head-injured patients.

Adolescent↗
PubMedDate not supplied

Equipoise and the ethics of the Canadian Lung Volume Reduction Surgery Trial study: should there be a randomized, controlled trial to evaluate lung volume reduction surgery?

The physical improvement is so great following lung volume reduction surgery that there is growing opinion that a randomized, controlled trial is unnecessary. A randomized, controlled trial, it is argued, would deprive those patients randomly assigned to the nonsurgical treatment arm the 'benefit' of lung volume reduction surgery. Entering a trial in which one arm leads to a surgical intervention and the other to best medical management also poses a variety of ethical difficulties. If one is to be offered surgery, there must be perceived benefit because the physician has an obligation to offer the best possible treatment for his or her patient. If a patient agrees to have surgery, the expectation is that surgery would help. Thus, a patient randomly assigned to the medical arm of a trial may easily believe that he or she is being deprived of surgery that may help them. This paper illustrates this dilemma using the Canadian Lung Volume Reduction Surgery Trial. The authors discuss the concept of 'equipoise' in three dimensions, adding community equipoise to theoretical equipoise and clinical equipoise earlier described by Freedman. The paper concludes that the Canadian Lung Volume Reduction Surgery Trial needs to continue because of the clinical equipoise that drives it.

Attitude of Health Personnel↗
PubMed2001

The CRASH trial: the first large-scale, randomised, controlled trial in head injury.

The global epidemic of head injuries is just beginning. Many are caused by road traffic crashes. It is estimated that, by 2020, road traffic crashes will have moved from its present position of ninth to third in the world disease burden ranking, as measured in disability adjusted life years. In developing countries, it will have moved to second. The Corticosteroid Randomisation After Significant Head Injury (CRASH) trial is a large-scale, randomised, controlled trial, among adults with head injury and impaired consciousness, of the effects of a short-term infusion of corticosteroids on death and on neurological disability. Following a successful pilot phase, which included over 1000 randomised participants, the main phase of the trial is now underway. Over the next 5 years, the trial aims to recruit a total of 20,000 patients. Such large numbers will only be possible if hundreds of doctors and nurses can collaborate in emergency departments all over the world. The trial is currently recruiting, and new collaborators are welcome to join the trial (see www.crash.lshtm.ac.uk).

Accidents, Traffic↗
PubMed1999

Global statistical tests for comparing multiple outcomes in rheumatoid arthritis trials. MIRA Trial Group.

OBJECTIVE: To evaluate global statistical tests (GSTs) of treatment effectiveness for rheumatoid arthritis (RA) trials measuring multiple outcomes. METHODS: Using outcome measures from American College of Rheumatology (ACR) core set variables available in 3 RA trials, GSTs were calculated using the O'Brien ranking procedure and a procedure for binary data. GSTs take correlations among outcomes into account. Power calculations using 1 trial data set provide comparisons of GSTs and ACR criteria for improvement. RESULTS: Spearman correlations among outcomes ranged from 0.21 to 0.73. Erythrocyte sedimentation rate had the lowest correlation with other outcomes in all 3 trials. Within a trial, joint swelling and joint tenderness or patient and physician assessment had the highest correlations, depending on the trial. Results were consistent with results using the ACR criteria, although the GST was more powerful. CONCLUSION: GSTs are a useful tool for comparing treatment effects across multiple clinically meaningful outcome measures. The GST allows easy inclusion of validated, reliable new measures that are not a part of ACR criteria, such as quality of life, and can be computed with or without selecting a cutoff point defining patient improvement. GSTs should be considered for rheumatic disease treatment trials.

Arthritis, Rheumatoid↗
PubMed2006

Flanker compatibility effects in patients with Parkinson's disease: impact of target onset delay and trial-by-trial stimulus variation.

Parkinson's disease (PD) patients and healthy controls were administered a flanker task that consisted of the presentation of colored targets and distractors. Participants were required to attend to the center target and identify its color. The stimulus displays were either congruent (i.e., the target and flankers were the same color) or incongruent. The time between the onset of the flanker and the target color (the target onset delay) was either short or long. Results indicated that PD patients and controls did not differ in the magnitude of the flanker effect within individual trials in that both groups demonstrated a typical flanker effect at the short target onset delay and neither group demonstrated a flanker effect at the longer delay. However, when performance was examined on a trial-by-trial basis, PD patients demonstrated a slowing of reaction time relative to controls when having to make the same response across consecutive trials at longer inter-trial intervals when the flankers were incongruent across consecutive trials and the display on the second of two trials was incongruent. These results indicate that PD patients are impaired in inhibiting the distractors over an extended delay and that this deficit may impact motor responding in these patients, suggesting that the basal ganglia contribute to the interface of attention and action.

Aged↗
PubMed1994

Carotid stenosis by digital subtraction angiography: reproducibility of the European Carotid Surgery Trial and the North American Symptomatic Carotid Endarterectomy Trial measurement methods and visual interpretation.

PURPOSE: To evaluate different carotid stenosis estimation methods with digital subtraction angiography. METHODS: We assessed the intraobserver reproducibilty and interobserver variability of visual interpretation and the measurement methods used by the European Carotid Surgery Trial and the North American Symptomatic Carotid Endarterectomy Trial. Angiographic stenosis measurements according to both criteria were performed twice by a radiologist, a neurologist, and a vascular surgeon. Eighty bifurcations of consecutive symptomatic patients underwent 480 pairs of measurements. In addition, four radiologists estimated the stenoses visually. RESULTS: Intraobserver consistency was slightly better by the European (kappa, 0.86 to 0.94) than by the North American (kappa, 0.68 to 0.91) trial criteria or by visual interpretation (kappa, 0.79 to 0.81). No significant interobserver variability was found, except in the subgroup of mild stenoses by the North American Trial criteria. By kappa statistic, the interobserver agreement was excellent by the European trial method (kappa, 0.72 to 0.86), good by the North American trial method (kappa, 0.59 to 0.77), and good to excellent by visual evaluation (kappa, 0.68 to 0.88). The visual estimation agreed more closely with the European (kappa, 0.73 to 0.92) than with the North American trial (kappa, 0.55 to 0.74) criteria measurements. CONCLUSIONS: All three methods have good reproducibility in digital subtraction angiography. Interobserver differences become more important in the estimation of mild stenosis.

Adult↗
PubMed1994

[Event related potentials and reaction time on auditory discrimination tasks (2nd report)--a study by trial-to-trial analysis].

Latency variability for single trial in the 4 components (N100, P200, N200 and P300) of the auditory event related potentials (ERP) and the temporal relationship to the choice reaction time (RT) were investigated in 11 normal subjects. Identification of each latency on single trials was derived by using a correlational-template procedure. Results showed that the mean value of the single trial latency in the 4 components was close to the peak latency in the averaged waveform. Significantly larger coefficient of variation was obtained for the N100 component and RT, when compared to the other components. Higher correlation between single trial latency and RT was found for N200 and P300 components. The P300 component latency yielded a significant temporal effect across trials (p < 0.05) showing increases in its latency in the later trials, whereas none of the RT did. These results may indicate that the P300 component latency is influenced directly by subtle changes in cerebral activities during an initial stage of human cognitive function occurring in each trial, whereas RT is additionally influenced by greater functional fluctuation during the process of motor execution for making responses.

Acoustic Stimulation↗