Reliability of 95% confidence interval revealed by expected quality-of-life scores: an example of nasopharyngeal carcinoma patients after radiotherapy using EORTC QLQ-C 30.

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  • Author(s): Chien TW;Chien TW; Lin SJ; Wang WC; Leung HW; Lai WP; Chan AL
  • Source:
    Health and quality of life outcomes [Health Qual Life Outcomes] 2010 Jul 13; Vol. 8, pp. 68. Date of Electronic Publication: 2010 Jul 13.
  • Publication Type:
    Journal Article; Research Support, Non-U.S. Gov't
  • Language:
    English
  • Additional Information
    • Source:
      Publisher: BioMed Central Country of Publication: England NLM ID: 101153626 Publication Model: Electronic Cited Medium: Internet ISSN: 1477-7525 (Electronic) Linking ISSN: 14777525 NLM ISO Abbreviation: Health Qual Life Outcomes Subsets: MEDLINE
    • Publication Information:
      Original Publication: [London] : BioMed Central, c2003-
    • Subject Terms:
      Confidence Intervals* ; Models, Statistical* ; Quality of Life*; Nasopharyngeal Neoplasms/*radiotherapy; Aged ; Female ; Humans ; Male ; Middle Aged ; Probability Theory ; Reproducibility of Results ; Surveys and Questionnaires
    • Abstract:
      Background: Many researchers use observed questionnaire scores to evaluate score reliability and to make conclusions and inferences regarding quality-of-life outcomes. The amount of false alarms from medical diagnoses that would be avoided if observed scores were substituted with expected scores is interesting, and understanding these differences is important for the care of cancer patients. Using expected scores to estimate the reliability of 95% confidence intervals (CIs) is rarely reported in published papers. We investigated the reliability of patient responses to a quality-of-life questionnaire and made recommendations for future studies of the quality of life of patients.
      Methods: A total of 115 patients completed the EORTC core questionnaire QLQ-C30 (version 3) after radiotherapy. The observed response scores, assumed to be one-dimensional, were summed and transformed into expected scores using the Rasch rating scale model with WINSTEPS software. A series of simulations was performed using a unified bootstrap procedure after manipulating scenarios with different questionnaire lengths and patient numbers to estimate the reliability at 95% confidence intervals. Skewness analyses of the 95% CIs were compared to detect different effects between groups according to the two data sets of observed and expected response scores.
      Results: We found that (1) it is necessary to report CIs for reliability and skewness coefficients in papers; (2) data derived from expected response scores are preferable to making inferences; and (3) visual representations displaying the 95% CIs of skewness values applied to item-by-item analyses can provide a useful interpretation of quality-of-life outcomes.
      Conclusion: Reliability coefficients can be reported with 95% CIs by statistical software to evaluate the internal consistency of respondent scores on questionnaire items. The SPSS syntax procedures for estimating the reliability of the 95% CI, expected score generation and visual skewness analyses are demonstrated in this study. We recommend that effect sizes such as a 95% CI be reported along with p values reporting significant differences in quality-of-life studies.
    • References:
      J Appl Meas. 2000;1(1):83-106. (PMID: 12023559)
      Med Care Res Rev. 2009 Jun;66(3):235-71. (PMID: 19176833)
      Eur J Cancer. 2000 Sep;36(14):1796-807. (PMID: 10974628)
      Health Qual Life Outcomes. 2010 Apr 30;8:45. (PMID: 20433690)
      BMC Health Serv Res. 2009 Jul 31;9:135. (PMID: 19646267)
      Health Qual Life Outcomes. 2009 May 05;7:39. (PMID: 19416521)
      BMC Med Res Methodol. 2009 Jun 17;9:38. (PMID: 19534773)
      Qual Life Res. 2006 May;15(4):607-20. (PMID: 16688494)
    • Publication Date:
      Date Created: 20100715 Date Completed: 20110228 Latest Revision: 20211020
    • Publication Date:
      20240104
    • Accession Number:
      PMC2912790
    • Accession Number:
      10.1186/1477-7525-8-68
    • Accession Number:
      20626903