Participants and setting
The study is of a methodological type that was conducted to translate and evaluate the psychometric properties of the H-SCALE. Participants were patients with hypertension referred to the clinic of Qom educational and medical center, Iran selected through the convenience sampling method. Inclusion criteria were age equal to and over 18 years, diagnosis of hypertension by a cardiologist, no mental or cognitive impairment, at least 6 months after diagnosis of disease, ability to communicate and respond, and consent to participate in the study. A sample size greater than or equal to 100 recommended for validate a scale. Two hundred and eighteen patients were included in the study according to the criteria after obtaining permission from the university Vice Chancellor for Research and coordination with educational and medical centers. Then, the purpose of the project and how to do it was explained to the participants. The questionnaires were completed within 6 months after ensuring the confidentiality of the information with the researcher and obtaining their consent.
Measures
To collect data, H-SCALE, The Morisky Medication Adherence Scale (MMAS-8), and demographic and medical information were used:
The H-SCALE questionnaire includes six subscales and 31 questions. First, drug adherence including 3 questions that examine adherence to drug use in the last 7 days. The score of each question is from 0 to 7 and the total score is from 0 to 21 points. A person who gets a score of 21 has a positive attitude. Second, nutrition including 10 questions about healthy eating (low fat and low salt diet, avoiding salt while cooking and eating, and avoiding high salt foods and fruits and vegetables) 7 questions of which should be reversed. The score range of each question is from 0 to 7 and the overall score is from 0 to 70. The positive score for each question is a score of 6 out of 7. That means a high score of 60 is a positive score. Third, physical activity consisting of 2 questions, the score range of each is from 0 to 7 and the overall score range is 0 to 14. Those who score higher than 8 have positive behavior. Fourth, tobacco consisting of 2 questions, the range of each being from 0 to 7 and the overall score is from 0 to 14. Those who choose zero days have a positive attitude.Fifth, weight Management containing 9 questions on 0 to 5 Likert scale (strongly agree to strongly disagree) that measure weight control behaviors in the past month. The score range is from 9 to 45 and the score above 35 is positive in weight management.
The MMAS-8 has seven two-point options and one five-point option (never = zero, rarely = 1, sometimes = 2, often = 3, always = 4 points) and obtaining a score of six or higher represents optimal adherence to treatment. The MMAS-8 was translated into Persian by Ghani Gheshlagh et al. (2015) and its validity and reliability were also confirmed. Demographic and disease information questionnaire included age and sex, level of education, monthly income, housing status, employment status, duration of illness and comorbidiy.
Translation and validation of Persian version
To perform the translation process, the recommended backward-forward method based on the protocol of the International Quality of Life Assessment Project (IQoLAP) was used (18). For this purpose, first, 2 fluent English translators performed 2 separate translations of the English version of the questionnaire into Persian. The original Persian version of the above two translations was obtained by considering the better translation. Next, two English language experts re-translated the final version into English. After this stage, the original English version was compared with the English version obtained by the translation of language experts by the research team, and finally, with the necessary corrections and editing, the final Persian version was approved. To determine the formal validity, the writing style, wording and logical and interesting appearance of the scale are used. For this purpose, the questionnaire was given to 10 older people who met the inclusion criteria and they were asked to express their opinions about the content, clarity, eligibility, simplicity and easy understanding of the instrument terms and the ease of completing the questionnaire. In this section, the level of difficulty (difficulty in understanding phrases and words), the degree of appropriateness (appropriateness and good relationship of phrases with the dimensions of the questionnaire) and ambiguity (the possibility of misunderstandings of phrases or the existence of inadequacies in the meanings of words) were examined. Also, the opinions of experts in the content validity stage were used to improve the formal validity of the scale. For this purpose, 5 related experts were asked to provide the necessary feedback after a qualitative review of the questionnaire based on the criteria of grammar, use of appropriate words, necessity, importance, placement of phrases in their proper place and proper scoring.
In order to determine the validity of the construct in this study, the Known Group Comparison was used, which is used to determine the extent to which the questionnaire can separate different subgroups. In other words, this type of validity determines the capability and ability of a scale in differentiating respondents according to the set criteria and assumptions. In this study, the parameter used was disease control. For this purpose, the scale score was compared between two groups of patients with and without blood pressure control using independent t-test. We expected people with controlled disease to score higher on the questionnaire than patients without controlled blood pressure. In order to evaluate the validity of the criterion, Pearson correlation coefficient was measured as the score of two questionnaires of H-SCALE and MMAS-8.
Confirmatory factor analysis method was used to determine the validity of the structure. In this section, convergent validity and divergent validity of the questionnaire were examined by Smart PLS software. Factor loads, mean extraction variance (AVE) and combined reliability are used to measure convergence validity. For convergent validity, all factor loads must be above 0.6 and significant. The mean of extracted variance is greater than 0.5 and the combined reliability is greater than the mean of extracted variance. Divergent validity is measured by cross loading, Fornell-Larcker test and Heterotrait-Monotrait Ratio. In the cross loading, the factor load of each question on its own construct must be greater than the factor load of that question on other constructs, ie the factor load of each question on its variable must be at least 0.1 greater than the factor load of the same question on other variables. In Fornell Larcker test, the root mean square of the extracted variance of each variable must be greater than the maximum correlation of that variable with other variables. The Heterotrait-Monotrait Ratio (HTMT) is also a reliable and new method for assessing divergent validity. If the values of HTMT index are below 0.9, the construct validity of the questionnaire is confirmed (19).
Internal consistency, composite reliability, and communalities are the main criteria used to assess the reliability of the questionnaire. Cronbach's alpha above 0.6, the composite reliability above 0.7 and the communalities index above 0.5 are confirmed (20).