This study aimed at measuring the validity and reliability of the Persian form of ET in advanced cancer patients. To achieve this goal, reliability, content, face, predictive, convergent, and divergent validity methods have been used, and the results of all of them indicate that it is an appropriate tool for assessing the emotional state of advanced cancer patients.
During cancer treatment, especially in the advanced stage, maintaining or improving the patients’ quality of life and decreasing their distress are important goals (
36,
37). Therefore, the distress of patients should be well recognized. As a result, it is necessary for appropriate tools to identify distress and intervene to reduce it. Although several tools have been designed through recent decades, according to experts, the right instrument for assessing distress and quality of life should have favorable psychometric characteristics and be multidimensional (
38). In selecting a screening tool, however, there are trade-offs to be made among brevity and ease of administration and scoring, and most importantly, the effectiveness of the scale in identifying distress. ET is the tool to measure psychological fluctuations during the disease and treatment and it is an easy and rapid instrument for detection, screening, and monitoring of patients’ emotional distress that it also has a simple visual-analog design. It is facile for most people including seniors and children to understand and complete (
18). In order to use ET, like any other scientific instrument, it needs to be reliable and valid. Therefore, we guess that using this scale in clinical settings and future research in Iran will encourage healthcare teams and researchers.
The assessment of the convergent validity of the scale showed that all emotional thermometers have a direct and strong relationship with HADS. According to the results, among the thermometers, the anxiety thermometer had the most relationship with hospital anxiety and depression thermometer with hospital depression. Regarding the divergent validity of ET with MQOL, it was also found that all thermometers had a significant and reverse relationship with quality of life and among them, respectively, the anxiety and depression thermometers have the highest correlation with the quality of life variable. Therefore, given the results and the advantages of this tool (fewer items, less time to respond, simplicity, visibility, and suitability for children, elderly, and even illiterate people), its use is preferred to the other 2 tools.
In order to investigate the predictive validity of the research variables after recoding the HADS scores based on cut-off line of the questionnaire, the results of logistic analysis showed that the model based on 5 variables of prediction (distress, anxiety, depression, anger, and need for help) could significantly predict the classification of people with anxiety and depression in non-affected individuals. As expected, among 5 emotional thermometers, the anxiety and depression thermometers with the rate of the total success of 86% and 80% have a significant role in the correct prediction of hospital anxiety and depression.
Moreover, the sensitivity and specificity for predicting the presence and absence of hospital anxiety were calculated, in which the sensitivity and specificity of the anxiety thermometer (with a cut-off line of 3 to 4) in prediction were 0.97 and 0.68, respectively. Also, the sensitivity and specificity for predicting the presence and absence of hospital depression were 0.82 and 0.74, respectively. These results, which show the sensitivity and specificity of the two anxiety and depression thermometers, are also better than previous research results (
22,
26).
In sum, all these results show the high validity of this tool, which is consistent with previous researches (
22,
25,
26). In fact, this tool has a good ability to use it in Iranian advanced cancer patients.
Likewise, the reliability of the scale was evaluated by the test-retest method via the Pearson correlation coefficient. As it would be expected from the majority of previous research in different countries (
25), the results showed that the test-retest correlation coefficient for distress, anxiety, depression, anger, and need for help was 0.81, 0.83, 0.84, 0.88, and 0.81, respectively; these results indicate the reliability of thermometers.
The most important point of this study is to prepare the novel scale, which can help healthcare teams to identify distress in advanced cancer patients by the short and sufficiently accurate way.
There were some limitations in this study that should be considered when interpreting these findings. Firstly, we used convenience sampling method; hence, we cannot extrapolate the results to fit the entire population. Hospitalizing of all the participants is another limitation; so, generalizing the results to out-patients should be cautious. Also, this tool is used to investigate emotional distress and, therefore, cannot assess physical aspects (such as heart rate) and cognitive aspects (such as rumination).
Despite these limitations, the primary findings of this study have implications for the diagnosis of the patients’ distress, which can help the screening of high-risk patients, who are in this situation. Actually, it would be advantageous to focus on reducing or controlling specific sources of distress and, at the same time, designing targeted preventative programs or treatments. Furthermore, systematic screening allows the healthcare team to forecast their workload.
5.1. Conclusions
The results of this study demonstrate that new Persian form of the ET is valid and reliable, which is consistent with previous studies. Therefore, the translated ET can be an appropriate tool for the appraisal of advanced cancer patients and evaluating the efficiency of interventions performed on these specific patients. It can also help the psychologists to recognize the distress quickly and, then, help to control them and improve the quality of life of the patients. However, since this study was a preliminary study, it is recommended that this scale should be examined in a larger group of patients and, consequently, its results would be generalized well and used safely.