The Development and Reliability of the New Zealand Secretion Scale

Abstract

The presence of accumulated pharyngo-laryngeal secretions is associated with aspiration, malnutrition, weight loss, and pneumonia. Given the clinical outcomes associated with accumulated secretions, it is critical that psychometrically sound measures are used for their assessment. Whilst traditional secretion scales evaluate location and amount, response to secretions has not yet been addressed. Guided by principles of scale development, the New Zealand Secretion Scale (NZSS) was developed for the comprehensive assessment of pharyngo-laryngeal secretions during endoscopy. The eight-point scale assesses secretion severity under the subcategories of location, amount, and response. This study is the first to systematically evaluate the NZSS. The first aim of the study was to provide preliminary evaluation of the scale’s content and psychometric characteristics. This guided the systematic refinement of the NZSS and strengthened its measurement properties. Central item means, strong item correlations, and good internal consistency were established. The second aim of the study was to evaluate the reliability of the NZSS. Researchers achieved excellent inter-rater (ICC = 0.99) and intra-rater reliability (ICC = 0.95) using the NZSS. Clinicians of varying levels of experience with endoscopy reached good inter-rater reliability (ICC = 0.71), with no prior training on the scale. The NZSS is a useful addition to the standardised endoscopic assessment. It is a quick and reliable assessment of secretion severity and can be used without training. The NZSS can reliably be used by clinicians with varying levels of experience to guide clinical decision making regarding the management and oral intake of high-risk patients. The inclusion of amount, location, and response to secretions provides the opportunity to evaluate all aspects of secretion management. Properties unique to this scale will also facilitate further research investigating the predictive value of accumulated secretions.