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Al-Asadi M, Sherren M, Abdel Khalik H, Leroux T, Ayeni OR, Madden K, Khan M. The Continuous Fragility Index of Statistically Significant Findings in Randomized Controlled Trials That Compare Interventions for Anterior Shoulder Instability. Am J Sports Med 2024:3635465231202522. [PMID: 38258495 DOI: 10.1177/03635465231202522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
BACKGROUND Evidence-based care relies on robust research. The fragility index (FI) is used to assess the robustness of statistically significant findings in randomized controlled trials (RCTs). While the traditional FI is limited to dichotomous outcomes, a novel tool, the continuous fragility index (CFI), allows for the assessment of the robustness of continuous outcomes. PURPOSE To calculate the CFI of statistically significant continuous outcomes in RCTs evaluating interventions for managing anterior shoulder instability (ASI). STUDY DESIGN Meta-analysis; Level of evidence, 2. METHODS A search was conducted across the MEDLINE, Embase, and CENTRAL databases for RCTs assessing management strategies for ASI from inception to October 6, 2022. Studies that reported a statistically significant difference between study groups in ≥1 continuous outcome were included. The CFI was calculated and applied to all available RCTs reporting interventions for ASI. Multivariable linear regression was performed between the CFI and various study characteristics as predictors. RESULTS There were 27 RCTs, with a total of 1846 shoulders, included. The median sample size was 61 shoulders (IQR, 43). The median CFI across 27 RCTs was 8.2 (IQR, 17.2; 95% CI, 3.6-15.4). The median CFI was 7.9 (IQR, 21; 95% CI, 1-22) for 11 studies comparing surgical methods, 22.6 (IQR, 16; 95% CI, 8.2-30.4) for 6 studies comparing nonsurgical reduction interventions, 2.8 for 3 studies comparing immobilization methods, and 2.4 for 3 studies comparing surgical versus nonsurgical interventions. Significantly, 22 of 57 included outcomes (38.6%) from studies with completed follow-up data had a loss to follow-up exceeding their CFI. Multivariable regression demonstrated that there was a statistically significant positive correlation between a trial's sample size and the CFI of its outcomes (r = 0.23 [95% CI, 0.13-0.33]; P < .001). CONCLUSION More than a third of continuous outcomes in ASI trials had a CFI less than the reported loss to follow-up. This carries the significant risk of reversing trial findings and should be considered when evaluating available RCT data. We recommend including the FI, CFI, and loss to follow-up in the abstracts of future RCTs.
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Affiliation(s)
- Mohammed Al-Asadi
- Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | | | - Hassaan Abdel Khalik
- Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, Ontario, Canada
| | - Timothy Leroux
- Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Olufemi R Ayeni
- Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, Ontario, Canada
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
| | - Kim Madden
- Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, Ontario, Canada
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
| | - Moin Khan
- Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, Ontario, Canada
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
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Ho AMH, Sehgal A, Leitch J, Saha T, Mizubuti GB. Comment on: The fragility index of randomized controlled trials in pediatric anesthesiology. Can J Anaesth 2024; 71:163-164. [PMID: 37989936 DOI: 10.1007/s12630-023-02658-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 09/28/2023] [Accepted: 09/28/2023] [Indexed: 11/23/2023] Open
Affiliation(s)
- Anthony M-H Ho
- Department of Anesthesiology and Perioperative Medicine, Queen's University, Kingston, ON, Canada
| | - Anupam Sehgal
- Department of Pediatrics, Kingston General Hospital, Queen's University, Kingston, ON, Canada
| | - Jordan Leitch
- Department of Anesthesiology and Perioperative Medicine, Queen's University, Kingston, ON, Canada
| | - Tarit Saha
- Department of Anesthesiology and Perioperative Medicine, Queen's University, Kingston, ON, Canada
| | - Glenio B Mizubuti
- Department of Anesthesiology and Perioperative Medicine, Queen's University, Kingston, ON, Canada.
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Ho AK, Zamperoni KE, Ho AMH, Mizubuti GB. Introducing the fragility index-A case study using the Term Breech Trial. Birth 2023; 50:11-15. [PMID: 36576726 DOI: 10.1111/birt.12698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/02/2022] [Accepted: 11/21/2022] [Indexed: 12/29/2022]
Abstract
The fragility index (FI) is a sensitivity analysis of the statistically significant result of a clinical study. It is the number of hypothetical changes in the primary event of one of the two cohorts in a 1-to-1 comparative trial to render the statistically significant result non-significant (ie, to alter the P-value from ≤0.05 to >0.05). The FI can be compared with the patient drop-out rates and protocol violations, which, if much higher than the FI, may arguably suggest less robustness/stability of the trial's results. To illustrate the concept, we have chosen the Term Breech Trial (TBT) as a case study. The TBT results favor planned cesarean birth, as opposed to planned vaginal delivery, in the term singleton fetus with breech presentation. Our analysis shows that the FI of the TBT is 21, which is small in comparison to the number (hundreds) of protocol violations present. Some experts have suggested the inclusion of the FI in data analysis and subsequent discussion of clinical trial data. Routine use of such a metric may be valuable in encouraging readers to maintain a healthy degree of skepticism, especially when interpreting trial results which may directly influence clinical practice.
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Affiliation(s)
- Adrienne K Ho
- Department of Public Health Sciences (Epidemiology), Queen's University School of Medicine, Kingston, Ontario, Canada
| | | | - Anthony M H Ho
- Department of Anesthesiology and Perioperative Medicine, Queen's University School of Medicine, Kingston, Ontario, Canada
| | - Glenio B Mizubuti
- Department of Anesthesiology and Perioperative Medicine, Queen's University School of Medicine, Kingston, Ontario, Canada
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Xing A, Lin L. Empirical assessment of fragility index based on a large database of clinical studies in the Cochrane Library. J Eval Clin Pract 2023; 29:359-370. [PMID: 36322140 PMCID: PMC9928801 DOI: 10.1111/jep.13787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 10/10/2022] [Accepted: 10/16/2022] [Indexed: 11/05/2022]
Abstract
RATIONALE AIMS AND OBJECTIVES The fragility index (FI) and fragility quotient (FQ) are increasingly used measures for assessing the robustness of clinical studies with binary outcomes in terms of statistical significance. The FI is the minimum number of event status modifications that can alter a study result's statistical significance (or nonsignificance), and the FQ is calculated as the FI divided by the study's total sample size. The literature has no widely recognized criteria for interpreting the fragility measures' magnitudes. This article aims to provide an empirical assessment for the FI and FQ based on a large database of clinical studies in the Cochrane Library. METHODS We explored the overall empirical distributions of the FI and FQ based on five common methods (Fisher's exact test, χ2 test, risk difference, odds ratio, and relative risk) for determining statistical significance of binary outcomes in clinical research. We also considered three different scenarios for the FI calculation and evaluated the relationship between p values and FIs or FQs using Spearman'sρ $\rho $ . Finally, we summarized empirical thresholds based on the overall distributions of the FI and FQ to facilitate their interpretations in future research. RESULTS For about 20% of studies with significant results, the statistical significance was changed after modifying the event status of only one participant. Studies with significant results were considered slightly fragile if the significance hinged on the statuses of about five events. Studies were extremely fragile if FI≤ $\le $ 1 or FQ≤ $\le $ 0.01. The FIs were strongly correlated with p values for significant studies, while Spearman'sρ $\rho $ varied according to the total sample sizes of studies. CONCLUSIONS The statistical significance of clinical studies could be changed after modifying a few events' statuses. Many studies' findings are fairly fragile. The distributions of the FI and FQ provide insights for appraising the robustness of evidence in clinical decision-making.
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Affiliation(s)
- Aiwen Xing
- Biostatistics and Research Decision Sciences, Merck & Co., Inc., Rahway, NJ, USA
- Department of Statistics, Florida State University, Tallahassee, FL, USA
| | - Lifeng Lin
- Department of Epidemiology and Biostatistics, University of Arizona, Tucson, AZ, USA
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Lin L, Xing A, Chu H, Murad MH, Xu C, Baer BR, Wells MT, Sanchez-Ramos L. Assessing the robustness of results from clinical trials and meta-analyses with the fragility index. Am J Obstet Gynecol 2023; 228:276-282. [PMID: 36084702 PMCID: PMC9974556 DOI: 10.1016/j.ajog.2022.08.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 11/21/2022]
Abstract
The fragility index has been increasingly used to assess the robustness of the results of clinical trials since 2014. It aims at finding the smallest number of event changes that could alter originally statistically significant results. Despite its popularity, some researchers have expressed several concerns about the validity and usefulness of the fragility index. It offers a comprehensive review of the fragility index's rationale, calculation, software, and interpretation, with emphasis on application to studies in obstetrics and gynecology. This article presents the fragility index in the settings of individual clinical trials, standard pairwise meta-analyses, and network meta-analyses. Moreover, this article provides worked examples to demonstrate how the fragility index can be appropriately calculated and interpreted. In addition, the limitations of the traditional fragility index and some solutions proposed in the literature to address these limitations were reviewed. In summary, the fragility index is recommended to be used as a supplemental measure in the reporting of clinical trials and a tool to communicate the robustness of trial results to clinicians. Other considerations that can aid in the fragility index's interpretation include the loss to follow-up and the likelihood of data modifications that achieve the loss of statistical significance.
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Affiliation(s)
- Lifeng Lin
- Department of Epidemiology and Biostatistics, University of Arizona, Tucson, AZ; Department of Statistics, Florida State University, Tallahassee, FL.
| | - Aiwen Xing
- Department of Statistics, Florida State University, Tallahassee, FL
| | - Haitao Chu
- Statistical Research and Innovation, Global Biometrics and Data Management, Pfizer Inc, New York, NY; Division of Biostatistics, University of Minnesota School of Public Health, Minneapolis, MN
| | - M Hassan Murad
- Evidence-Based Practice Center, Mayo Clinic, Rochester, MN
| | - Chang Xu
- Ministry of Education Key Laboratory for Population Health Across-Life Cycle & Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, Anhui, China; School of Public Health, Anhui Medical University, Anhui, China
| | - Benjamin R Baer
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY
| | - Martin T Wells
- Department of Statistics and Data Science, Cornell University, Ithaca, NY
| | - Luis Sanchez-Ramos
- Department of Obstetrics and Gynecology, College of Medicine, University of Florida, Jacksonville, FL
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Gupta A, Ortiz-Babilonia C, Xu AL, Rogers D, Vulcano E, Aiyer AA. The Statistical Fragility of Platelet-Rich Plasma as Treatment for Plantar Fasciitis: A Systematic Review and Simulated Fragility Analysis. FOOT & ANKLE ORTHOPAEDICS 2022; 7:24730114221144049. [PMID: 36582654 PMCID: PMC9793046 DOI: 10.1177/24730114221144049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background Plantar fasciitis (PF) is the most common cause of heel pain and can be a source of extensive physical disability and financial burden. Platelet-rich plasma (PRP) offers a potentially definitive, regenerative treatment modality that, if effective, could change the current paradigm of PF care. However, randomized controlled trials (RCTs) on the clinical benefits of PRP for refractory PF offer inconsistent conclusions, potentially because of the broader limitations of using P value thresholds to declare statistical and clinical significance. In this study, we use the Continuous Fragility Index (CFI) and Quotient (CFQ) to appraise the statistical robustness of data from RCTs evaluating PRP for treatment of PF. Methods RCTs comparing outcomes after PRP injection vs alternative treatment in patients with chronic PF were evaluated. Representative simulated data sets were generated for each reported outcome event using summary statistics. The CFI was determined by manipulating each data set until reversal of significance (α=0.05) was achieved. The corresponding CFQ was calculated by dividing the CFI by the sample size. Results Of 259 studies screened, 20 studies (59 outcome events) were included in this analysis. From these simulations, the median CFI for all events was 9, suggesting that varying the treatment of 9 patients would be required to reverse trial significance. The corresponding CFQ was 0.177. Studies with reported P value <.05 were more statistically fragile (CFI=10, CFQ=0.122) than studies with reported P value >.05 (CFI=5, CFQ=0.179). Of 36 outcome events reporting lost to follow-up data, 10 events (27.8%) lost ≥9 patients. Conclusion Our findings suggest that, on average, the statistical fragility of RCTs evaluating PRP for nonoperative PF therapy is at least comparable to that of the sports medicine literature. However, several included studies had concerningly low simulated fragility scores. Orthopaedic surgeons may benefit from preferentially relying on studies with higher CFI and CFQ values when evaluating the utility of PRP for chronic PF in their own clinical practice. Given the importance of RCT data in clinical decision making, fragility indices could help give context to the stability of statistical findings. Level of Evidence Level I, systematic review.
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Affiliation(s)
- Arjun Gupta
- Department of Orthopaedic Surgery, The
Johns Hopkins University School of Medicine, Baltimore, MD, USA,Department of Orthopaedic Surgery,
Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Carlos Ortiz-Babilonia
- Department of Orthopaedic Surgery, The
Johns Hopkins University School of Medicine, Baltimore, MD, USA,Department of Orthopaedic Surgery,
University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Amy L. Xu
- Department of Orthopaedic Surgery, The
Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Davis Rogers
- Department of Orthopaedic Surgery, The
Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ettore Vulcano
- Department of Orthopaedic Surgery,
Columbia University Mount Sinai Medical Center, Miami, FL, USA
| | - Amiethab A. Aiyer
- Department of Orthopaedic Surgery, The
Johns Hopkins University School of Medicine, Baltimore, MD, USA,Amiethab A. Aiyer, MD, Department of
Orthopaedic Surgery, The Johns Hopkins Hospital, 1800 Orleans St, Baltimore, MD
21287, USA.
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Xu AL, Ortiz-Babilonia C, Gupta A, Rogers D, Aiyer AA, Vulcano E. The Statistical Fragility of Platelet-Rich Plasma as Treatment for Chronic Noninsertional Achilles Tendinopathy: A Systematic Review and Meta-analysis. FOOT & ANKLE ORTHOPAEDICS 2022; 7:24730114221119758. [PMID: 36051864 PMCID: PMC9424894 DOI: 10.1177/24730114221119758] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background: Randomized controlled trial (RCT) outcomes reaching statistical significance,
frequently determined by P <.05, are often used to guide
decision making. Noted lack of reproducibility of some RCTs has brought
special attention to the limitations of this approach. In this
meta-analysis, we assessed the robustness of RCTs evaluating platelet-rich
plasma (PRP) for the treatment of chronic noninsertional Achilles
tendinopathy (AT) by using fragility indices. Methods: The present study was a systematic review and meta-analysis of RCTs comparing
outcomes after PRP injection vs alternative treatment in patients with AT.
Representative data sets were generated for each reported continuous outcome
event using summary statistics. Fragility indices refer to the minimal
number of patients whose status would have to change from a nonevent to an
event to turn a statistically significant result into a nonsignificant
result, or vice versa. The fragility index (FI) and continuous FI (CFI) were
determined for dichotomous and continuous outcomes, respectively, by
manipulating each data set until reversal of significance (a=0.05) was
achieved. The corresponding fragility quotient (FQ) and continuous FQ (CFQ)
were calculated by dividing FI/CFI by sample size. Results: Of 432 studies screened, 8 studies (52 outcome events) were included in this
analysis. The 12 dichotomous outcomes had a median FI of 4.5 (FQ: 0.111),
and the 40 continuous outcomes had a median CFI of 5 (CFQ: 0.154). All 52
outcome events included lost-to-follow-up data, and 12 (23.1%) indicated a
greater number of patients lost to follow-up than the FI or CFI. Conclusion: Our findings suggest that RCTs evaluating PRP for AT therapy lack statistical
robustness, because changing only a small number of events may alter outcome
significance. Level of Evidence: Level II, therapeutic study.
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Affiliation(s)
- Amy L. Xu
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Carlos Ortiz-Babilonia
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Orthopaedic Surgery, University of Puerto Rico Medical Sciences Campus, San Juan, PR
| | - Arjun Gupta
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Orthopaedic Surgery, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Davis Rogers
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Amiethab A. Aiyer
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ettore Vulcano
- Department of Orthopaedic Surgery, Columbia University Mount Sinai Medical Center, Miami, FL, USA
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Ibarra-Estrada M, Li J, Laffey JG, Pavlov I, Roca O, Perez Y, McNicholas B, Vines D, Tavernier E, Ehrmann S. Prone positioning might reduce the need for intubation in people with severe COVID-19 - Authors' reply. THE LANCET. RESPIRATORY MEDICINE 2021; 9:e111. [PMID: 34861160 PMCID: PMC8631898 DOI: 10.1016/s2213-2600(21)00449-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Miguel Ibarra-Estrada
- Unidad de Terapia Intensiva, Hospital Civil Fray Antonio Alcalde, Guadalajara, Mexico
| | - Jie Li
- Department of Cardiopulmonary Sciences, Division of Respiratory Care, Rush University, Chicago, IL 60612, USA.
| | - John G Laffey
- Department of Anesthesia and Intensive Care Medicine, Galway University Hospitals, HRB Galway Clinical Research Facility, and School of Medicine, National University of Ireland, Galway, Ireland
| | - Ivan Pavlov
- Department of Emergency Medicine, Hôpital de Verdun, Montreal, QC, Canada
| | - Oriol Roca
- Servei de Medicina Intensiva, Hospital Universitari Vall d'Hebron, Barcelona, Spain; Ciber Enfermedades Respiratorias (CibeRes), Instituto de Salud Carlos III, Madrid, Spain
| | - Yonatan Perez
- CHRU Tours, Médecine Intensive Réanimation, CIC INSERM 1415, CRICS-TriggerSep FCRIN research network, Tours, France; INSERM, Centre d'étude des pathologies respiratoires, U1100, Université de Tours, Tours, France
| | - Bairbre McNicholas
- Department of Anesthesia and Intensive Care Medicine, Galway University Hospitals, HRB Galway Clinical Research Facility, and School of Medicine, National University of Ireland, Galway, Ireland
| | - David Vines
- Department of Cardiopulmonary Sciences, Division of Respiratory Care, Rush University, Chicago, IL 60612, USA
| | - Elsa Tavernier
- Clinical Investigation Center, INSERM 1415, CHRU Tours, Tours, France; Methods in Patients-Centered Outcomes and Health Research, INSERM UMR 1246, Nantes, France
| | - Stephan Ehrmann
- CHRU Tours, Médecine Intensive Réanimation, CIC INSERM 1415, CRICS-TriggerSep FCRIN research network, Tours, France; INSERM, Centre d'étude des pathologies respiratoires, U1100, Université de Tours, Tours, France
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