An Evaluation of the Psychometric Properties of the Edmonton Symptom Assessment System in a New Zealand Community Hospice Setting
Palliative patients experience substantial and distressing symptoms that impact on their quality of life. To date, a ‘gold standard’ measure is it yet to be identified for symptom assessment in palliative care. The Edmonton Symptom Assessment System (ESAS) is the most commonly used measure to assess symptoms within palliative care throughout the world. Various studies have investigated the reliability and validity of the ESAS. However, these studies have revealed inconsistent validity and have predominately focused the measures use in populations with cancer only diagnoses.
The cases of all patients admitted to a community hospice setting in New Zealand over the six month period December 2015-May 2016, were reviewed for this study (n=229). As part of the usual admitting process, the registered nurse conducts several health related assessment measures; including the ESAS and a performance status measure, the ECOG. The scores of the ESAS and the ECOG were anonymised and collated for data analysis.
The psychometric properties of the 12-item, numeric rating scale version of the ESAS were evaluated using descriptive statistics, exploratory factor analysis, and Rasch analysis. Exploratory factor analysis found three factors. One: drowsiness, tiredness, appetite, wellbeing, and complexity, two: anxiety, depression, and shortness of breath, three: constipation, nausea, insomnia, and pain. Rasch analysis confirmed that the ESAS is a unidimensional scale. Uniform rescoring of the ESAS indicated that the validity of item scoring could be improved by collapsing scoring options from 11 options to four options.
The ESAS is shown to have some evidence of validity and reliability for assessing symptoms within the present research setting of New Zealand, community palliative care. However, the present study identified inconsistent factor structures. Therefore, several areas of key focus for future research has been identified to further validate the use of the ESAS within the New Zealand community palliative care setting.