This descriptive-analytical cross-sectional study was conducted on the elderly in Sirjan in 2020. Inclusion criteria included willingness to participate in the study, age 60 years and older, and having no speech disorder and Alzheimer's disease. Exclusion criteria included unwillingness to participate in the study. The sample size was calculated according to a similar study conducted by Barghi Irani et al. 15. In their study, the correlation coefficient between variables of lifestyle, psychological capital and self-care behaviors in the elderly ranged from 0.3 to 0.5. After searching and not finding a similar study, it was assumed that the correlation coefficient between healthy lifestyle, self-esteem and subjective vitality is similar to the reference mentioned above and at least 0.3. The following formula was used to determine the sample size:
Assuming type I error was 0.01 and type II error was 0.1, according to the formula, at least 159 people were calculated and for better estimation, 200 people were included in the study. Two-stage random sampling method was used for sampling. Among 12 comprehensive health centers in Sirjan, 4 centers were randomly selected and then by referring to selected centers, a list of elderly people eligible to participate in the study was prepared from each center and then 50 people from each list entered the study by simple random method. It continued until it reached the desired sample size of 200 people.
The data were collected using a four-part questionnaire. The first part was related to demographic information (including age, gender, level of education, marital status, and employment status) and the second part was a 46-item questionnaire measuring a healthy lifestyle among Iranian elderly, which was designed and validated by Eshaghi et al. (2007 and 2008) in Isfahan: 15 questions in the field of accident prevention, 5 questions in the field of sports, 14 questions in the field of healthy nutrition, 5 questions in the field of stress management and 7 questions in the field of social relations. The questions were coded on a 5-point Likert scale (very low, low, moderate, high and very high) and the lowest score of the questionnaire was 42 and the highest score was 211. In a study by Babak et al., the face and content validity of this questionnaire was confirmed and Cronbach's alpha coefficient was calculated to be 0.76 16.
The third part of Rosenberg Self-Esteem Scale was used, which measures a person's attitude toward himself with 10 items on the Likert scale (strongly agree, agree, disagree, and strongly disagree). The range of scores of this questionnaire varies from 10 to 40, with the score 10 as the lowest and 40 as the highest self-esteem. This scale is a valid and reliable tool. Greenberger et al. validated this tool using its structural validity 17. Also, Hojjati et al. reported its reliability with Cronbach's alpha coefficient of 0.78 18.
The fourth part used Subjective Vitality Scale, designed by Ryan and Frederick. The internal consistency of this scale was reported to be 0.96 in their study. This tool contains 7 questions that are scored on a 7-point Likert scale. The scores range from 7 to 35. In a study by Arabzadeh, the reliability of this tool was calculated with Cronbach's alpha coefficient of 0.79 11.
In the present study, the content validity was used to measure the validity of Healthy Lifestyle and Subjective Vitality Questionnaire. First, the questionnaires were given to ten experts in the field of health education and health promotion (n = 5) and elderly health (n = 5) to determine the quality validity of the content. After receiving the correction suggestions, the incorrect questions were corrected and the inappropriate questions were removed and replaced with other questions. Then, in order to determine the quantity validity of the content, they were first asked to review the questionnaire item in terms of the following: which questions should be included in the questionnaire, which questions are useful but unnecessary, and which questions are not necessary and should be excluded. Second, whether the questions of each construct reflect the relevant construct, and finally the simplicity, clarity and cultural appropriateness of each question were assessed. Given that we had ten experts, the minimum value for the content validity according to the criteria in Lawshe table was considered 0.62 19.
According to the formula CVR = \(\frac{{\text{n}}_{\text{E}}\text{-}\frac{\text{N}}{\text{2}}}{\frac{\text{N}}{\text{2}}}\) content validity was calculated for each item. According to the results, the content validity in the Healthy Lifestyle Questionnaire was more than 0.62 for 33 items and in the range of 0.7 to 1, which were confirmed, and for 13 items, it was less than 0.62, which were removed. The content validity of subjective vitality questionnaire was more than 0.62 for 5 items and in the range of 0.7 to 1, which were confirmed, and for 2 items was less than 0.62, which were excluded. Also, in order to determine the content validity of each item, the opinions of the experts in the form of three criteria of relevance, simplicity and clarity on a 4-point Likert scale (for example 1: not relevant, 2: somewhat relevant, 3: relevant and 4: completely related) received for each criterion. In order to calculate the content validity according to the formula CVI = \(\frac{\text{n}}{\text{N}}\) the number of experts agreeing with the first two options of each criterion for each item was calculated and divided by the total number of experts i.e. 10, and thus, CVI of each item was determined. The minimum value of the content validity is 0.79 20. The results of calculating CVI for Healthy Lifestyle Questionnaire showed that every 33 items had CVI score higher than 0.79 and were considered appropriate. The value of validity for all constructs was calculated by averaging the item of each construct. Finally, the value of content validity of prevention was 0.82, 0.87 for healthy nutrition, 0.92 for exercise, 0.87 for stress management and 0.85 for social relations. Thus, Healthy Lifestyle Questionnaire has 33 questions and includes 5 fields of prevention (11 questions), healthy nutrition (10 questions), exercise (4 questions), stress management (4 questions), social relations (4 questions) and all questions were scored on a 5-point Likert scale (very high, high, moderate, low, very low and never), and "very high" was given a score of 5 and "very low and never" were given a score of 1. Questions 5, 6 and 7 were scored in reverse. As a result, for a healthy lifestyle, the lowest score achieved through the questionnaire was 33 and the highest score was 165. Also, the results of CVI calculation for Subjective Vitality Questionnaire showed that all 5 items had CVI score higher than 0.79 and were considered appropriate. The value of content validity for the questionnaire was 0.87. As a result, Subjective Vitality Questionnaire consisted of 5 questions that were scored on a 5-point Likert scale (strongly disagree, disagree, have no opinion, agree, and strongly agree), and "strongly disagree" was given a score of 1 and "strongly agree" was given a score of 5. Also, the lowest score obtained from this questionnaire was 5 and the highest score was 25. After evaluating the validity, the reliability of these two questionnaires was calculated by Cronbach's alpha and retest-test. Cronbach's alpha coefficient for prevention was 0.71, 0.74 for healthy nutrition, 0.84 for exercise, 0.74 for stress management, 0.70 for social relations and 0.85 for the whole healthy lifestyle questionnaire, indicating good reliability. Also, to determine the reliability of the tool, the test-retest method was used and the reliability of prevention, healthy nutrition, exercise, stress management, social relations and the whole questionnaire was equal to 0.75, 0.83, 0.78, 0.91, 0.75, and 0.83, respectively and all of them were significant at p < 0.001. The reliability of Subjective Vitality Questionnaire was obtained from calculating Cronbach's alpha coefficient equal to 0.73, which was good. Also, the test-retest method was used and interclass correlation coefficient was 0.75.
The method was that after receiving the code of ethics ID IR.KMU.REC.1399.598 and an official letter of introduction from Kerman University of Medical Sciences and coordination with the Department for Health of Sirjan School of Medical Sciences and Health Services, a list of all elderly eligible to participate in the study was prepared from selected comprehensive health centers. Then, by a simple random method, a number of elderly people were selected and invited to participate in the study by phone, while introducing themselves, explaining the objectives and emphasizing the confidentiality of their information. If they want to participate in the study and have all inclusion criteria, their consent was obtained verbally and then the researcher read each question and explain how to answer it, and recorded the answer to each question in the questionnaire. This continued until the sample size reached 200 people. Descriptive statistics including absolute frequency, frequency distribution table, mean and standard deviation were used for data analysis. Given that the distribution of the studied variables was not normal after Kolmogorov-Smirnov test, inferential statistics including non-parametric Mann-Whitney, Kruskal-Wallis, Post Hoc and Spearman correlation coefficients were used. The software used for data analysis was SPSS version 20 and in all cases the significance level was considered less than 0.05.