Following the objectives of this study, our discussions of the results are summarized into 4 points as follows:
The prevalence of Type D Personality
The prevalence of type D personality in the present study was 14.6% which is less than the previous studies (Denollet, 2005; Hausteiner et al., 2010; Molloy et al., 2012; Petrowski et al., 2017; Shao et al., 2017; Wu et al., 2015). The closest prevalence of other studies was found from a survey conducted in the Netherlands, with 18.1% of type D personality from 215 patients with hypertension (Mommersteeg et al., 2010).
The proportion of elder participants was 84.60% which may explain this lower prevalence. Stressors in retired people differ from younger people or those of working age, so this might be one factor responsible for decreased work and socioeconomic stress. In Thai society, most elders tend to spend their leisure time with their religious beliefs which has positive effects on mental health.
The prevalence found is close to that found in other Asian countries such as the 18.2% prevalence of type D personality in type 2 diabetic patients in Chinese patients (Shao et al., 2017). Likewise, the prevalence of type D personality in Korean healthy, CHD, and hypertension groups was 27% (Lim et al., 2011). In contrast, when compared to the findings in western countries, more significant differentiations was found: a study in Belgium and the Netherlands among healthy group, CHD patients and hypertensive patients, 21%, 28%, and 54% were categorized as type D, respectively (Denollet, 2005).
The differentiation of factors like ethnicity and culture between Europeans and Asians could have some relevance to this diversity of prevalence (Goziev, 2016). In western groups, individualism and freedom might be more important than in an eastern group. In addition, in asking about agreement with some statements in the DS-14 questionnaire like “I often feel unhappy; I take a gloomy view of thing; I am often in a bad mood; I find it hard to start a conversation; and, I am a closed kind of person,” could have been perceived as more negative in Asian cultures. Especially, being friendly and having close relationships in Thai context could have affected SI scores.
As to gender-speciﬁc effects, this study found that the prevalence of type D personality in males (20.47%) was more than in females (11.71%). This finding differs from the data collected in Augsburg, Germany, which found fewer males than females, 23.4% to 26.9%, respectively (Hausteiner et al., 2010). In the same way, another study with a German sample reported that the prevalence in males was 31.3%, and for females, the prevalence was 38.4% (Grande et al., 2004). Results show that most participants were elders (the average age was 67.55 years old). The 8th stage (65 years +) from Erik Erikson's Stages of Psychosocial Development, Integrity vs. Despair, could be relevant (Erickson, 1998). Erikson explained that stressors of people in this stage usually come from health conditions from degeneration and stress. Seniors feel stress in adapting to retirement and developing life satisfaction, happiness, and peacefulness. In Thai context, males usually play a dominant role in the family, and by transferring to a dependent stage experience stress from a feeling of emasculation, especially when not prepared.
The difference of Self-Efficacy between Type D and Non-Type D Personality Groups
This study found that mean scores of medication self-efficacy in these two groups (36.76:35.77) were significantly different. This difference implies that those of type D personality often have negative feelings toward both situations and themselves. This affect and inhibition can lead to unhappiness, anxiety, and frustration. The social inhibition describes how persons often feel uncomfortable when it comes to social situations because they are afraid of being rejected, that is relevant since persons with type D personality tend to show lower self-efficacy score (Petrowski et al., 2017).
The difference of Self-Care Behavior between Type D and Non-Type D Personality Groups
This study found that mean scores of self-care behavior between type D personality group and others are significantly different. The difference implies that people with type D personality have hypertension self-care behaviors different from others, as seen in previous studies. Several studies present evidence that those of type D personality tend to have lower medication adherence when compared to others (Li et al., 2016; Wu et al., 2015). In conclusion, they described that people with type D personality are less interested in taking care of their health and have a hard time following healthy self-care behavior patterns as suggested.
This lack of attention is consistent with the results of this study which found that the type D personality group had lower self-efficacy score than those without type D personality. Bandura’s theory of self-efficacy describes self-efficacy as people’s belief that they can handle any situation and control it until attaining their goal (Bandura, 1978). In this context, when type D patients have low self-efficacy, they also tend to have low health behavior control.
Correlations among Medication Self-Efficacy, Self-Care Behavior and Type D Personality
A positive relationship between medication self-efficacy and self-care behavior was found. This finding is maybe a result of one’s belief in medication self-control which can lead to one’s decisions weather act. One study in African-American subjects reported an association between high self-efficacy and good hypertension self-care behavior in 5 behaviors out of 6 (Warren-Findlow, Seymour, & Brunner Huber, 2012). Focusing on a similar population, a hypothesis that medication adherence and self-efficacy have a significant relationship was proven (Francois, 2015), also the finding that patients who have high self-efficacy reported tendency of high medication adherence and better control of hypertensive symptoms were found (Elder et al., 2012).
An inverse relationship between type D personality and medication self-efficacy was found. This finding agrees with those which found a tendency of low medication adherence in type D personality patients (Wu et al., 2015). As well, compared in The General Self-Efficacy Scale that showed lower self-efficacy scores in those of type D personality as compared to others (Petrowski et al., 2017).
Focusing on two domains of type D personality, which are negative affectivity and social inhibition, an inverse relationship with medication self-efficacy was found. This finding can be supported by the result which both negative affectivity and social inhibition showed a negative association with self-efficacy (Shao et al., 2017). Also, there was a study reported that after discharge from the hospital for six months, 30% of patients who were type D personality have a significant lower medication adherence (Molloy et al., 2012). Also, an association between negative affectivity and medication adherence can be explained by an indirect effect of medication self-efficacy.
This study found type D personality has an inverse association with self-care behavior. Likewise, the report stated that patients with type D personality significantly have low medication adherence (Li et al., 2016). Another study showed that patients with type D personality tend to have lower levels of medication self-efficacy and medication adherence than others (Wu et al., 2015). Besides, the results of this study presented the same when each of two domains was analyzed, with both negative affectivity and social inhibition having an inverse association with self-care behavior.