scholarly journals Comparison of Time-to-First Event and Recurrent-Event Methods in Randomized Clinical Trials

Circulation ◽  
2018 ◽  
Vol 138 (6) ◽  
pp. 570-577 ◽  
Author(s):  
Brian Claggett ◽  
Stuart Pocock ◽  
L.J. Wei ◽  
Marc A. Pfeffer ◽  
John J.V. McMurray ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Statistical Power ◽  
Recurrent Events ◽  
Randomized Clinical Trials ◽  
Cox Model ◽  
Study Drug ◽  
Recurrent Event ◽  
Drug Discontinuation ◽  
Patient Heterogeneity ◽  
Study Drug Discontinuation

Background: Most phase-3 trials feature time-to-first event end points for their primary and secondary analyses. In chronic diseases, where a clinical event can occur >1 time, recurrent-event methods have been proposed to more fully capture disease burden and have been assumed to improve statistical precision and power compared with conventional time-to-first methods. Methods: To better characterize factors that influence statistical properties of recurrent-event and time-to-first methods in the evaluation of randomized therapy, we repeatedly simulated trials with 1:1 randomization of 4000 patients to active versus control therapy, with true patient-level risk reduction of 20% (ie, relative risk=0.80). For patients who discontinued active therapy after a first event, we assumed their risk reverted subsequently to their original placebo-level risk. Through simulation, we varied the degree of between-patient heterogeneity of risk and the extent of treatment discontinuation. Findings were compared with those from actual randomized clinical trials. Results: As the degree of between-patient heterogeneity of risk increased, both time-to-first and recurrent-event methods lost statistical power to detect a true risk reduction and confidence intervals widened. The recurrent-event analyses continued to estimate the true relative risk (0.80) as heterogeneity increased, whereas the Cox model produced attenuated estimates. The power of recurrent-event methods declined as the rate of study drug discontinuation postevent increased. Recurrent-event methods provided greater power than time-to-first methods in scenarios where drug discontinuation was ≤30% after a first event, lesser power with drug discontinuation rates of ≥60%, and comparable power otherwise. We confirmed in several actual trials of chronic heart failure that treatment effect estimates were attenuated when estimated via the Cox model and that increased statistical power from recurrent-event methods was most pronounced in trials with lower treatment discontinuation rates. Conclusions: We find that the statistical power of both recurrent-events and time-to-first methods are reduced by increasing heterogeneity of patient risk, a parameter not included in conventional power and sample size formulas. Data from real clinical trials are consistent with simulation studies, confirming that the greatest statistical gains from use of recurrent-events methods occur in the presence of high patient heterogeneity and low rates of study drug discontinuation.

MMRM vs joint modeling of longitudinal responses and time to study drug discontinuation in clinical trials using a “de jure” estimand

2020 ◽  
Vol 19 (6) ◽  
pp. 909-927
Author(s):  
Alberto García‐Hernandez ◽  
Teresa Pérez ◽  
María del Carmen Pardo ◽  
Dimitris Rizopoulos
Keyword(s):  
Clinical Trials ◽  
Study Drug ◽  
Joint Modeling ◽  
Drug Discontinuation ◽  
Study Drug Discontinuation

scholarly journals Sex, Permanent Drug Discontinuation, and Study Retention in Clinical Trials

Circulation ◽  
2021 ◽  
Vol 143 (7) ◽  
pp. 685-695 ◽  
Author(s):  
Emily S. Lau ◽  
Eugene Braunwald ◽  
David A. Morrow ◽  
Robert P. Giugliano ◽  
Elliott M. Antman ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Clinical Trials ◽  
Study Drug ◽  
Similar Proportion ◽  
Trial Participation ◽  
Drug Discontinuation ◽  
Random Effects Models ◽  
Cardiovascular Outcome Trials ◽  
Study Drug Discontinuation ◽  
The Individual

Background: Women are underrepresented across cardiovascular clinical trials. Whether women are more likely than men to prematurely discontinue study drug or withdraw consent once enrolled in a clinical trial is unknown. Methods: Eleven phase 3/4 TIMI (Thrombolysis in Myocardial Infarction) trials were included (135 879 men and 51 812 women [28%]). The association between sex and premature study drug discontinuation and withdrawal of consent were examined by multivariable logistic regression after adjusting for potential confounders in each individual trial and combining the individual point estimates in random effects models. Results: After adjusting for baseline differences, women had 22% higher odds of premature drug discontinuation (adjusted odds ratio [OR adj ], 1.22 [95% CI, 1.16–1.28]; P <0.001) compared with men. Qualitatively consistent results were observed for women versus men in the placebo arms (OR adj , 1.20 [95% CI, 1.13–1.27]) and active therapy arms (OR adj , 1.23 [95% CI, 1.17–1.30)]; there was some evidence for regional heterogeneity ( P interaction <0.001). Of those who stopped study drug prematurely, a similar proportion of men and women in the active arm stopped because of an adverse event (36% for both; P =0.60). Women were also more likely to withdraw consent compared with men (OR adj , 1.26 [95% CI, 1.17–1.36]; P <0.001). Conclusions: Women were more likely than men to prematurely discontinue study drug and withdraw consent across cardiovascular outcome trials. Premature study drug discontinuation was not explained by baseline differences by sex or a higher proportion of adverse events. Future trials should better capture reasons for drug discontinuation and withdrawal of consent to understand barriers to continued study drug use and clinical trial participation, particularly among women.

scholarly journals Are clinical trial results transferable in the real life?

2016 ◽  
Vol 84 (1-2) ◽  
Author(s):  
Enrico Natale ◽  
Alfiera Marsocci
Keyword(s):  
Clinical Trial ◽  
Clinical Trials ◽  
Clinical Practice ◽  
Recurrent Events ◽  
Randomized Clinical Trials ◽  
Real Life ◽  
Recurrent Event ◽  
The Real ◽  
Number Of Patients ◽  
Clinical Trial Results

<p>Generally in the clinical practice patients are more complex in comparison with those included in the clinical trials. In this article, we discuss three relevant items, which may implement the transferability of the clinical trial results in the real world. The observational studies have fewer restrictions on the number of patients included, due to more relaxed inclusion and exlusion criteria than in randomized clinical trials. The absence of randomization however may lead to potential for bias. The recurrent event analysis may extend the positive results of clinical trials regarding the reductions of the first primary endpoint event to total events, including those beyond the first event. This analysis is of great interest in the clinical practice, where recurrent events are common. Finally the reliability of subgroup analysis is discussed. Pre-specified subgroup analyses are more credible and valuable than <em>post-hoc</em> analyses.</p><p><strong>Riassunto</strong></p><p>Nella pratica clinica i pazienti sono generalmente più complessi rispetto alle popolazioni studiate nei trial clinici. Si rendono necessari pertanto strumenti di analisi che integrino i trial clinici. In questo articolo vengono esaminati alcuni punti di rilevante importanza nella definizione di una corretta applicabilità dei risultati dei trial clinici al mondo reale. Il primo punto riguarda il ruolo e i limiti degli studi osservazionali. Il secondo tratta delle analisi degli eventi ricorrenti, una modalità di analisi dei trial clinici che rende i risultati più aderenti alla vita reale, nella consapevolezza che limitare i dati di outcome al primo evento sia riduttivo rispetto alla necessità di stabilire che l’intervento studiato nel trial confermi la sua efficacia anche sugli eventi successivi al primo. Il terzo punto riguarda la controversa questione delle analisi per sottogruppi, uno strumento utile per generare ipotesi, ma discutibile quando impiegato per rimediare a trial con risultati negativi o estendere i risultati di trial positivi a sottopopolazioni particolari di pazienti. </p>

scholarly journals Evaluation of the Value of Attribution in the Interpretation of Adverse Event Data: A North Central Cancer Treatment Group and American College of Surgeons Oncology Group Investigation

2010 ◽  
Vol 28 (18) ◽  
pp. 3002-3007 ◽  
Author(s):  
Shauna L. Hillman ◽  
Sumithra J. Mandrekar ◽  
Brian Bot ◽  
Ronald P. DeMatteo ◽  
Edith A. Perez ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Treatment Group ◽  
Cancer Treatment ◽  
Randomized Clinical Trials ◽  
Study Drug ◽  
Phase Iii ◽  
Oncology Group ◽  
North Central ◽  
American College Of Surgeons ◽  
Group Trial

Purpose In March 1998, Common Toxicity Criteria (CTC) version 2.0 introduced the collection of attribution of adverse events (AEs) to study drug. We investigate whether attribution adds value to the interpretation of AE data. Patients and Methods Patients in the placebo arm of two phase III trials—North Central Cancer Treatment Group Trial 97-24-51 (carboxyamino-triazole v placebo in advanced non–small-cell lung cancer) and American College of Surgeons Oncology Group Trial Z9001 (imatinib mesylate v placebo after resection of primary gastrointestinal stromal tumors)—were studied. Attribution was categorized as unrelated (not related or unlikely) and related (possible, probable, or definite). Results In total, 398 patients (84 from Trial 97-24-51 and 314 from Trial Z9001) and 7,736 AEs were included; 47% and 50% of the placebo-arm AEs, respectively, were reported as related. When the same AE was reported in the same patient on multiple visits, the attribution category changed at least once 36% and 31% of the time. AE type and sex (Trial Z9001) and AE type and performance status (Trial 97-24-51) were associated with a higher likelihood of AEs being deemed related. Conclusion Nearly 50% of AEs were reported as attributed to study drug on the placebo arm of two randomized clinical trials. These data provide strong evidence that AE attribution is difficult to determine, unreliable, and of questionable value in interpreting AE data in randomized clinical trials.

scholarly journals 1374. Integrated Safety Summary of Omadacycline: A Novel Aminomethylcycline Antibiotic

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S421-S421 ◽  
Author(s):  
Steven Opal ◽  
Thomas M File ◽  
Tom Van Der Poll ◽  
Paul McGovern ◽  
Evan Tzanis ◽  
...  
Keyword(s):  
Adverse Events ◽  
Fungal Infections ◽  
Vital Signs ◽  
Study Drug ◽  
Drug Discontinuation ◽  
Once Daily ◽  
Atypical Pathogens ◽  
Safety Parameters ◽  
Study Drug Discontinuation ◽  
Electrocardiogram Ecg

Abstract Background Omadacycline (OMC) is a novel aminomethylcycline with activity against Gram-positive, many Gram-negative, anaerobic, and atypical pathogens. It is in clinical development as once-daily oral (PO) and intravenous (IV) monotherapy for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP). Cumulative safety results from Phase 3 clinical trials are reported. Methods This pooled safety analysis is based on 2,150 subjects: OASIS-1 (N = 645), OASIS-2 (N = 735) in ABSSSI; OPTIC (N = 770) in CABP. Comparators were linezolid (LZD) 600 mg IV then PO in ABSSSI (n = 689); moxifloxacin (MOX) 400 mg IV then PO in CABP (n = 388). Safety parameters included treatment-emergent adverse events (TEAEs), laboratory evaluations, vital signs, and electrocardiogram (ECG) findings. Results A total of 1,073 subjects received OMC: 705 received OMC IV then PO (ABSSSI, n = 323; CABP, n = 382); 368 received OMC PO only for ABSSSI. Overall, 60.6% were male and 91.6% white; mean age ranges were 44.7–45.1 and 60.9–62.1 years in ABSSSI and CABP studies, respectively. TEAEs were observed in 47.5% (OMC), 41.2% (LZD), and 48.5% (MOX) of subjects, with gastrointestinal events the most common TEAEs. Serious TEAEs were low (3.6% OMC, 1.9% LZD, 6.7% MOX). Nausea (14.9% OMC, 8.7% LZD, 5.4% MOX) and vomiting (8.3% OMC, 3.9% LZD, 1.5% MOX) were the most frequently reported TEAEs. Diarrhea was observed in 2.4% OMC, 2.9% LZD, and 8.0% MOX subjects, with no cases of Clostridium difficile in OMC-treated subjects. Most TEAEs were mild to moderate and did not result in study drug discontinuation (3.1% OMC, 1.5% LZD, 7.0% MOX); 4 OMC, 1 LZD, and 0 MOX subjects discontinued for nausea and vomiting. Frequency of hepatic TEAEs was similar for OMC, LZD, and MOX: 4.3% OMC, 4.1% LZD, and 4.5% MOX subjects had post-baseline ALT &gt;3× upper limit of normal. Vital signs and ECGs had comparable clinically notable values post-baseline in each treatment group. Known tetracycline class adverse events such as fungal infections were similar in all groups. Conclusion Pooled analyses demonstrate a favorable OMC safety profile, consistent with its tetracycline heritage. OMC was generally well tolerated in subjects with ABSSSI and CABP, with infrequent treatment discontinuations. Disclosures T. M. File Jr., BioMerieux: Consultant, Consulting fee; Curetis: Consultant, Consulting fee; Melinta Therapeutics: Consultant, Consulting fee; Merck: Consultant, Consulting fee; Motif Bio: Consultant, Consulting fee; Nabriva Therapeutics: Consultant and Investigator, Consulting fee and Research grant; Paratek Pharmaceuticals: Consultant, Consulting fee; Pfizer: Consultant, Consulting fee. T. Van Der Poll, Paratek Pharmaceuticals: Consultant, Consulting fee. P. McGovern, Paratek Pharmaceuticals: Employee, Salary. E. Tzanis, Paratek Pharmaceuticals: Employee, Salary.

scholarly journals 684. Cardiac Safety in Adults with Community-Acquired Bacterial Pneumonia (CABP) Treated with Lefamulin (LEF) or Moxifloxacin (MOX): Analysis of Lefamulin Evaluation Against Pneumonia (LEAP) 1 and LEAP 2 Study Results

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S311-S311
Author(s):  
Borje Darpo ◽  
Anita F Das ◽  
Daniel Stein ◽  
Jennifer Schranz ◽  
Steven P Gelone
Keyword(s):  
Torsade De Pointes ◽  
Significant Risk ◽  
Study Drug ◽  
Qt Prolongation ◽  
Drug Discontinuation ◽  
Cardiac Safety ◽  
Study Results ◽  
Minute Interval ◽  
Clinically Significant ◽  
Study Drug Discontinuation

Abstract Background Preclinical data suggest potential effects of LEF on cardiac interval parameters. We therefore assessed LEF cardiac safety from the LEAP 1/2 trials. Methods In LEAP 1, PORT III–V patients received LEF 150mg IV q12h for 5–7 days or MOX 400mg IV q24h for 7 days, with optional IV-to-oral switch (600mg LEF q12h or 400 mg MOX q24h). In LEAP 2, PORT II–IV patients received oral LEF 600mg q12h for 5 days or oral MOX 400mg q24h for 7 days. Patients with known QT prolongation or on medication with potential to prolong the QT interval were excluded as per MOX label. After 5 minutes of rest in the supine position, triplicate 12-lead ECGs were obtained within a 5-minute interval at Screening in both studies, on Days 1/3 in LEAP 1 (predose and ≤15 minutes after first IV dose), and on Days 1/4 in LEAP 2 (predose and 1–3 hours after first oral dose), and sent to a central ECG reader for adjudication. Results Of 1,282 randomized/treated patients (n = 641/group), 1,274 had baseline (BL) and post-BL ECG data (n = 636 LEF, n = 638 MOX). Consistent with the resolution of infection, ECGs revealed mean reductions of 7–8 beats/minute for both groups in both studies. The largest mean change in QTcF from BL to post-BL was on Day 3 in LEAP 1 (13.6 and 16.4 msec with IV LEF and MOX, respectively) and on Day 4 in LEAP 2 (9.3 and 11.6 msec with oral LEF and MOX, respectively). The proportion of patients meeting potentially important post-BL QTcF values/changes was comparable between treatment groups (table). In the standardized MedDRA query of Torsade de pointes/QT prolongation (broad), the most common treatment-emergent adverse event was ECG QT prolonged (n = 4 LEF, n = 5 MOX). All events were nonserious and mild or moderate in severity. 6 events were considered study drug related (n = 4 LEF, n = 2 MOX). 5 events led to study drug discontinuation (n = 2 LEF, n = 3 MOX). In 2 patients with cardiovascular disease, 1 had ventricular arrhythmia on Day 20 (18 days after last LEF dose) and 1 had cardiac arrest on Day 18 (9 days after last MOX dose); both events were fatal and considered unrelated to study drug by investigator. Conclusion Mild prolongation of the QTcF interval was seen with LEF and MOX, with somewhat smaller effects seen with LEF. Given the small effect, LEF is unlikely to pose a clinically significant risk of ventricular proarrhythmia with appropriate precautions and use. Disclosures All authors: No reported disclosures.

scholarly journals Response by Claggett et al to Letter Regarding Article, “Comparison of Time-to-First Event and Recurrent-Event Methods in Randomized Clinical Trials”

Circulation ◽  
2019 ◽  
Vol 139 (3) ◽  
pp. 422-423
Author(s):  
Brian Claggett ◽  
Stuart Pocock ◽  
L. J. Wei ◽  
Marc A. Pfeffer ◽  
John J.V. McMurray ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Randomized Clinical Trials ◽  
Recurrent Event

scholarly journals The continuous heart failure spectrum: moving beyond an ejection fraction classification

2019 ◽  
Vol 40 (26) ◽  
pp. 2155-2163 ◽  
Author(s):  
Filippos Triposkiadis ◽  
Javed Butler ◽  
Francois M Abboud ◽  
Paul W Armstrong ◽  
Stamatis Adamopoulos ◽  
...  
Keyword(s):  
Heart Failure ◽  
Clinical Trials ◽  
Ejection Fraction ◽  
Statistical Power ◽  
Structural Changes ◽  
Randomized Clinical Trials ◽  
New Technologies ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ventricular Ejection Fraction

Abstract Randomized clinical trials initially used heart failure (HF) patients with low left ventricular ejection fraction (LVEF) to select study populations with high risk to enhance statistical power. However, this use of LVEF in clinical trials has led to oversimplification of the scientific view of a complex syndrome. Descriptive terms such as ‘HFrEF’ (HF with reduced LVEF), ‘HFpEF’ (HF with preserved LVEF), and more recently ‘HFmrEF’ (HF with mid-range LVEF), assigned on arbitrary LVEF cut-off points, have gradually arisen as separate diseases, implying distinct pathophysiologies. In this article, based on pathophysiological reasoning, we challenge the paradigm of classifying HF according to LVEF. Instead, we propose that HF is a heterogeneous syndrome in which disease progression is associated with a dynamic evolution of functional and structural changes leading to unique disease trajectories creating a spectrum of phenotypes with overlapping and distinct characteristics. Moreover, we argue that by recognizing the spectral nature of the disease a novel stratification will arise from new technologies and scientific insights that will shape the design of future trials based on deeper understanding beyond the LVEF construct alone.

scholarly journals 1347. Omadacycline for Acute Bacterial Skin and Skin Structure Infections: Integrated Analysis of Randomized Clinical Trials

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S412-S412 ◽  
Author(s):  
Fredrick M Abrahamian ◽  
George Sakoulas ◽  
Evan Tzanis ◽  
Amy Manley ◽  
Judith N Steenbergen ◽  
...  
Keyword(s):  
Clinical Response ◽  
Randomized Clinical Trials ◽  
Treatment Initiation ◽  
Study Drug ◽  
Lesion Size ◽  
Integrated Analysis ◽  
Drug Discontinuation ◽  
Gram Positive ◽  
Skin Structure ◽  
Infection Types

Abstract Background Skin infections are a significant medical burden for affected individuals and the healthcare system. The purpose of this investigation was to integrate the findings of two randomized studies of omadacycline (OMC) in ABSSSI. Methods OMC in Acute Skin and Skin Structure Infections Study (OASIS)-1 initiated patients on intravenous (IV) OMC or linezolid (LZD) with a possible transition to oral formulation after at least 3 days of IV therapy. OASIS-2 investigated oral-only OMC. Treatment duration in both studies was 7–14 days. Early clinical response (ECR) in the mITT population, the primary endpoint in both studies, was defined as a ≥20% reduction in lesion size at 48–72 hours after treatment initiation. The secondary endpoint was investigator assessment of clinical response (IACR) at post-therapy evaluation (PTE) in the mITT and CE populations, 7–14 days after treatment initiation. Results A total of 691 patients receiving OMC and 689 patients receiving LZD were included. The mean age of patients was 45 years, 64% were male, and 83% enrolled at US sites. Infection types: wound infections (46.8%), cellulitis/erysipelas (30.5%), major abscess (22.7%). Median lesion size was 316 cm2 and 304 cm2 in OMC and LZD patients, respectively. S. aureus was detected in 74.6% of patients, of which 43.4% had MRSA. 71% were mono-microbial Gram-positive infections, 15% were poly-microbial Gram-positive infections. OMC showed similar efficacy to LZD for the primary and secondary endpoints, as well as for mono-microbial and poly-microbial infections (figure). Clinical responses were similar across different infection types, lesion sizes, and baseline pathogens. Treatment-emergent adverse events (TEAEs), most mild or moderate, were reported by 51% and 41% of patients receiving OMC or LZD, respectively. Nausea and vomiting were more frequent for OMC patients in the OASIS-2 oral-only study while receiving the loading dose on Day 1 and 2. Serious AEs were reported by 2.3% and 1.9%, respectively. TEAEs leading to study drug discontinuation were reported by 1.7% and 1.5%, respectively. Conclusion The integrated analysis of OASIS trials showed that oral and IV omadacycline was effective in the treatment of ABSSSI and was safe and generally well-tolerated by patients. Disclosures F. M. Abrahamian, Allergan: Speaker’s Bureau, Speaker honorarium. Melinta: Speaker’s Bureau, Speaker honorarium. Merck: Speaker’s Bureau, Speaker honorarium. Nabriva: Scientific Advisor, Consulting fee. Paratek: Scientific Advisor, Consulting fee. G. Sakoulas, Allergan: Consultant and Speaker, Consulting fee and Speaker honorarium. Sunovion Pharmaceuticals: Speaker, Speaker honorarium. The Medicines Company: Speaker, Speaker honorarium. Paratek Pharmaceuticals: Consultant, Consulting fee. Cidara Therapeutics: Scientific Advisor, Consulting fee. Arsanis Pharmaceuticals: Scientific Advisor, Consulting fee. E. Tzanis, Paratek Pharmaceuticals: Employee, Salary. A. Manley, Paratek Pharmaceuticals: Employee and Shareholder, Salary. J. N. Steenbergen, Paratek Pharmaceuticals: Employee and Shareholder, Salary. A. Das, Achaogen: Consultant, Consulting fee. Cempra: Consultant, Consulting fee. Contrafect: Consultant, Consulting fee. Nabriva: Consultant, Consulting fee. Paratek: Consultant, Consulting fee. Tetraphase: Consultant, Consulting fee. Theravance: Consultant, Consulting fee. Wockhardt: Consultant, Consulting fee. P. Eckburg, Paratek: Consultant, Consulting fee. P. McGovern, Paratek Pharmaceuticals: Employee, Salary.

Statistical power of negative randomized clinical trials (RCTs) presented at the American Society of Clinical Oncology (ASCO) Annual Meetings

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 6516-6516
Author(s):  
P. Bedard ◽  
M. K. Krzyzanowska ◽  
M. Pintilie ◽  
I. F. Tannock
Keyword(s):  
Clinical Trials ◽  
Sample Size ◽  
Annual Meeting ◽  
Primary Endpoint ◽  
Effect Size ◽  
Statistical Power ◽  
Randomized Clinical Trials ◽  
Medium Effect ◽  
Post Hoc ◽  
Adequate Sample Size

6516 Background: Underpowered randomized clinical trials (RCTs) may expose participants to risks and burdens of research without scientific merit. We investigated the prevalence of underpowered RCTs presented at ASCO annual meetings. Methods: We surveyed all two-arm parallel phase III RCTs presented at the ASCO annual meeting from 1995–2003 where differences for the primary endpoint were non-statistically significant. Post hoc calculations were performed using a power of 80% and a=0.05 (two-sided) to determine the sample size required to detect a small, medium, and large effect size between the two groups. For studies reporting a proportion or time to event as a primary endpoint, effect size was expressed as an odds ratio (OR) or hazard ratio (HR) respectively, with a small effect size defined as OR/HR=1.3, medium effect size OR/HR=1.5, and large effect OR/HR=2.0. Logistic regression was used to identify factors associated with lack of statistical power. Results: Of 423 negative RCTs for which post hoc sample size calculations could be performed, 45 (10.6%), 138 (32.6%), and 333 (78.7%) had adequate sample size to detect small, medium, and large effect sizes respectively. Only 35 negative RCTs (7.1%) reported a reason for inadequate sample size. In a multivariable model, studies presented at plenary or oral sessions (p<0.0001) and multicenter studies supported by a co-operative group were more likely to have adequate sample size (p<0.0001). Conclusion: Two-thirds of negative RCTs presented at the ASCO annual meeting do not have an adequate sample to detect a medium-sized treatment effect. Most underpowered negative RCTs do not report a sample size calculation or reasons for inadequate patient accrual. No significant financial relationships to disclose.

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