Item Analysis of Quality of Life Scale (QLICP-NA, V2.0) for Nasopharyngeal Carcinoma Based on Classical Test theory and Item Response Theory

Abstract

Abstract [Objective] To analyze the QLICP-NA (V2.0) items using classical test theory and item response theory. [Methods]One hundred twenty-one nasopharyngeal carcinoma patients were investigated using QLICP-NA (V2.0). SPSS15.0 software was used to manage the data and Multilog 7.03 software was used for parameter analysis. IRT was used to calculate the discrimination, difficulty, and item information for each item in the scale. [Results] The scale covered five domains: physical (PHD); psychological (PSD); social (SOD); general symptoms and side effects (SSD); and special module (SNA). PHD contains eight items (coded GPH1-8), PSD comprises nine items (coded GPS1-9), SOD covers eight items (coded GSO1-8), SSD includes seven items (coded GSS1-7), and SNA covers eleven items (coded SNA1-11). The correlation coefficient between SNA1 and SNA8 was < 0.4, and the correlation was poor. GPS4, GOS4, SNA1, and SNA3 had low correlation with the field. The five items were deleted. SNA4 and SNA8 discrimination was poor, thus deletion was recommended. SNA2 and SNA10 discrimination was not good, thus SNA2 and SNA10 were modified and retained. The results of item information showed that the information content of the specific module, SNA1-11, was poor, but because deleting too many items had a great impact on the total table and deleting two items (SNA6 and SNA10) with < 0.2 information, 34 items were finally reserved. [Conclusion] The analysis of scale items can be evaluated from different angles and applied comprehensively.