Relationship between two anxiety instruments in patients receiving mechanical ventilatory support

Aims. The primary aim of this paper is to discuss the relationship between the Visual Analog Scale-Anxiety (VAS-A) and the Spielberger State Anxiety Inventory (SAI) in patients receiving mechanical ventilatory support. A secondary aim is to provide suggestions for the nurse-researcher to consider when selecting an instrument to measure anxiety. Background. Anxiety is a common experience for critically ill patients receiving mechanical ventilatory support. It is a challenge, however, for nurse-researcher to select an instrument to measure anxiety that is valid and reliable yet does not cause great response burden for participants. Visual analog scales may reduce response burden, but lack sound validation in research participants receiving mechanical ventilatory support. Methods. This study used a correlational design. A convenience sample of critically ill patients receiving mechanical ventilatory support (n = 200) were asked to rate their current level of anxiety on the 20-item Spielberger SAI and a 100-mm VAS-A. Results. Eight participants were unable to complete the Spielberger SAI; 100% completed the VAS-A. The two instruments were found to be significantly correlated at r = 0.50; P = 0.01. Conclusion. The VAS-A was found to be less burdensome for research participants than the Spielberger SAI, resulting in no missing data on the VAS-A. Findings from this study provide initial validation of the VAS-A as a justifiable instrument to measure anxiety in patients receiving mechanical ventilatory support. Researchers are advised to balance reliability and validity properties with response burden when selecting an instrument to measure anxiety in patients with communication challenges and energy limitations.