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

Rebecca G. Theophanous, Joao Ricardo Nickenig Vissoci, Fan Hui Wen, S. Michelle Griffin, Victoria E. Anderson, Michael E. Mullins, Nicklaus P. Brandehoff, Eugenia B. Quackenbush, Sean P. Bush, Eric A. Toschlog, Spencer C. Greene, Kapil Sharma, Kurt Kleinschmidt, Nathan P. Charlton, S. Rutherfoord Rose, Richard Schwartz, Brandon Lewis, Eric J. Lavonas, Charles J. Gerardo

Research output: Contribution to journalArticle


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.

Original languageEnglish (US)
Pages (from-to)e0007935
JournalPLoS neglected tropical diseases
Issue number12
StatePublished - Dec 1 2019


ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Infectious Diseases

Cite this

Theophanous, R. G., Vissoci, J. R. N., Wen, F. H., Griffin, S. M., Anderson, V. E., Mullins, M. E., Brandehoff, N. P., Quackenbush, E. B., Bush, S. P., Toschlog, E. A., Greene, S. C., Sharma, K., Kleinschmidt, K., Charlton, N. P., Rose, S. R., Schwartz, R., Lewis, B., Lavonas, E. J., & Gerardo, C. J. (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), e0007935.