Validity and reliability of telephone administration of the patient-specific functional scale for the assessment of recovery from snakebite envenomation.


OBJECTIVES:Although more than 1.8 million people survive snakebite envenomation each year, their recovery is understudied. Obtaining long-term follow-up is challenging in both high- and low-resource settings. The Patient-Specific Functional Scale (PSFS) is an easily administered, well-accepted patient-reported outcome that is validated for assessing limb recovery from snakebite envenomation. We studied whether the PSFS is valid and reliable when administered by telephone. METHODS:This is a secondary analysis of data from a randomized clinical trial. We analyzed the results of PSFS collected in-person on days 3, 7, 14, 21, and 28 and by telephone on days 10, 17, and 24. We assessed the following scale psychometric properties: (a) content validity (ceiling and floor effects), (b) internal structure and consistency (Cronbach's alpha), and (c) temporal and external validity using Intraclass Correlation Coefficient (ICC). Temporal stability was assessed using Spearman's correlation coefficient and agreement between adjacent in-person and telephonic assessments with Cohen's kappa. Bland Altman analysis was used to assess differential bias in low and high score results. RESULTS:Data from 74 patients were available for analysis. Floor effects were seen in the early post-injury time points (median: 3 (IQR: 0, 5) at 3 days post-enrollment) and ceiling effects in the late time points (median: 9 (IQR: 8, 10). Internal consistency was good to excellent with both in-person (Cronbach α: 0.91 (95%CI 0.88, 0.95)) and telephone administration (0.81 (0.73, 0.89). Temporal stability was also good (ICC: 0.83 (0.72, 0.89) in-person, 0.80 (0.68, 0.88) telephone). A strong linear correlation was found between in-person and telephone administration (Spearman's ρ: 0.83 (CI: 0.78, 0.84), consistency was assessed as excellent (Cohen's κ 0.81 (CI: 0.78, 0.84), and Bland Altman analysis showed no systematic bias. CONCLUSIONS:Telephone administration of the PSFS provides valid, reliable, and consistent data for the assessment of recovery from snakebite envenomation.






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Publication Info

Theophanous, Rebecca G, Joao Ricardo Nickenig Vissoci, Fan Hui Wen, S Michelle Griffin, Victoria E Anderson, Michael E Mullins, Nicklaus P Brandehoff, Eugenia B Quackenbush, et al. (2019). Validity and reliability of telephone administration of the patient-specific functional scale for the assessment of recovery from snakebite envenomation. PLoS neglected tropical diseases, 13(12). p. e0007935. 10.1371/journal.pntd.0007935 Retrieved from

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Rebecca George Theophanous

Associate Professor of Emergency Medicine

Rebecca Theophanous, MD, MHSc is an Emergency Ultrasound Faculty at Duke University Hospital and the Durham VA Healthcare System. Her research involves identifying facilitators and barriers to implementation of a new emergency ultrasound program at the Durham VAHCS and its impact on clinical care for future dissemination. She is also studying 3DUS technology at Duke as an innovative bedside tool and training ED providers on ultrasound. Her academic interests include medical education, with a focus on ultrasound and critical care.


Joao Ricardo Nickenig Vissoci

Assistant Professor in Emergency Medicine

Joao Ricardo Nickenig Vissoci, MSc, PhD is an Assistant Professor of Emergency Medicine, Neurosurgery and Global Health. He is the Chief of the Division of Translational Health Sciences in the Department of Emergency Medicine, co-Director of the Global Emergency Medicine Innovation and Implementation (GEMINI) Research Center and a faculty member of the Research Design and Analysis Core (RDAC) in the Duke Global Health Institute. Dr. Vissoci has a background in social psychology and data science. Dr. Vissoci, a Brazilian native, earned a bachelor’s degree in Psychology from State University of Maringá/Brazil, a Masters in Physical Education, an MBA in Human Resources, and a PhD in Social Psychology. During his PhD, he completed a fellowship in Data Science at Duke University. After graduating his PhD in Social Psychology from the Pontificia Universidade Católica of São Paulo/Brazil, Dr. Vissoci completed a postdoctoral fellowship at the University of Sao Paulo (2015) in Design and Analysis for Mental Health research. He completed a second postdoctoral fellowship at the Duke Global Health Institute in Global Health and Data Science in 2016. Dr. Vissoci held a faculty position and taught Public Health and Health Sciences in Brazil from 2009 to 2015. After completing his fellowship at DGHI, he joined the Duke Department of Emergency Medicine as faculty in 2017. In his last 14 years as faculty (2009-current), he has mentored over 200 trainees at all levels of training from undergraduate, graduate, medical education, postdoctoral to faculty level. He has published over 200 manuscripts and collaborated on over 6 R-level NIH grants, multiple (K and D) NIH training grants, other federal grants UK/Brazil based, and foundational grants.

His research interests focus on leveraging data through analytics and technology to bridge the gap in access and equity in care in low resource settings, translating evidence into practice or policy impact. He uses data science and mixed-methods research to design and implement innovative data-driven solutions to address health care gaps.


Charles J. Gerardo

Professor of Emergency Medicine

Dr. Gerardo is Professor and Chair for the Department of Emergency Medicine.  He graduated with honors from Stanford University with a Bachelor’s of Science in Biology, and received his MD degree from University of California, Davis.  He went on to complete his residency training in Emergency Medicine at Loma Linda University Medical Center.  He completed his Masters of Health Sciences from the Duke University Clinical Research and Training Program.  In 2000, he joined Emergency Medicine faculty at Duke University and has served in numerous educational, research and administrative leadership roles. His current research focuses on US and global snake envenomation using a variety of methodologies from transitional science and clinical trials to machine learning and implementation science. He has over 90 peer reviewed publications and book chapters, and is published in JAMA, PLOS Medicine, Annals of Emergency Medicine, Academic Emergency Medicine and Clinical Toxicology. 

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