Relationship between sense of coherence and lifestyle in middle-aged workers in Japan ()
1. INTRODUCTION
Recently in Japan, concern has emerged over metabolic syndrome as a multi-risk factor for the development of atherosclerotic disease, and visceral fat obesity has also become a serious issue [1]. In 2008, the results of a government study reported that 1 of 2 male participants and 1 of 5 female participants over 40 years of age had either metabolic syndrome or were at risk for metabolic syndrome. This finding suggests that lifestyle quality must be improved and maintained for the health of Japanese men and women [2]. Simply reducing food intake, however, does not lead to a healthy, obesity-free lifestyle [3]. Those at risk must improve a variety of lifestyle habits, such as exercise, sleep, and diet, in addition to improving food intake. Improving quality of life with regard to health and maintaining it requires an overall reassessment of lifestyle habits, rather than focus on only a single aspect.
Since the enactment of the Equal Employment Opportunity Act approximately 20 years ago in Japan, remarkable progress has been made in the social advancement of women, resulting in a large number of women holding positions of responsibility. Along with this advancement, Japanese women are likely experiencing the increased social stress traditionally experienced by men, and therefore more attention should be paid to the health of women from a lifestyle disease perspective. In NIPPON DATA 80, the predictive 10-year risk factors for death due to coronary artery disease in men were blood pressure level, blood sugar level, and cholesterol level. For women, the likelihood of death from coronary artery disease was not sufficient to provide significant predictive factors [4]. Sex differences might also be evident in health habits, beliefs, and the experience of stress [5]. Thus, more effective predictive indices are needed for health maintenance in women.
An indicator of the ability to establish and maintain quality of life in relation to health is a sense of coherence (SOC), the central notion proposed in Antonovsky’s salutogenesis theory [6]. SOC represents the capacity to maintain health and manage a variety of stressors in daily life. It comprises the three sub-concepts of 1) comprehensibility, 2) manageability, and 3) meaningfulness.
Although only a few reports exist, it is generally thought that subjects with a high SOC are able to cope more effectively with stressors by utilizing multiple general resistance resources to choose healthier lifestyle behaviors [7-9]. This effect differs among samples, however, and lifestyle behaviors reflected by the SOC remain unclear. We reported in a previous study that the SOC of university students is still being formed and does not reflect healthy lifestyle behaviors [10].
In the present study, a cross-sectional survey of middle-aged workers examined how SOC relates to health status. SOC, as an ability to maintain health, relates to lifestyle (cognition, behavior, and dietary habits), not only for deriving or being satisfied with well-being, but for health-rated quality of life. This study further aimed to determine the characteristic lifestyle factors for maintaining physical and psychological health.
2. METHODS
2.1. Participants and Survey Methods
In this study, participants responded to online survey items. All respondents were members of an Internet research service provider (Macromill, http://www. macromill.com/global/index.html), which has approximately 830,000 registered users, to align the work condition. Potential participants included men and women living in the southern Kanto region, which has the highest population of workers in Japan [11]. The questionnaire was administered twice, first as a preliminary survey and then as the main survey. On October 22, 2010, approximately 27,000 middle-aged users (40 - 59 years) of both sexes were randomly selected and recruited by email. Email messages contained information on informed consent and remuneration as well as a link to the questionnaire. Respondents were informed that upon completion of the questionnaire twice online, they would be compensated points worth a maximum of 90 yen (about 1 US Dollar) by the Internet research company. Of the 10,000 respondents, approximately 2000 full-time regular employees were selected. On October 26, 2010, 618 individuals were randomly selected from this group and invited by email to participate in the present study. Retrieved questionnaires with blanks or mistakenly entered items were excluded, and analysis was conducted on only valid responses. The study was approved by the ethics review board of the University of Human Arts and Sciences.
2.2. Survey Content
Survey items addressed SOC and lifestyle habits, specifically lifestyle factors of self-rated health, and level of physical and psychological health.
2.2.1. Level of Physical and Psychological Health
Self-rated health is a self-evaluative index of health status rated on a 5-point scale ranging from “very good” (5 points) to “poor” (1 point). Levels of overall lifestyle satisfaction, dietary satisfaction, and sleep satisfaction comprised the single index of sense of happiness. Each was rated on a 7-point scale ranging from “very satisfied” (7 points) to “very dissatisfied” (1 point). Stress was rated on a 5-point scale based on the degree of stress experienced on a daily basis ranging from “very high” (5 points) to “none” (1 point).
2.2.2. Lifestyle Factors
Lifestyle habits relating to health characteristics were investigated and included wake-up time, commute duration, frequency of consuming meals (breakfast, lunch, dinner, and snacks), and frequently eaten foods. The survey further examined whether respondents actively engaged in health practices, and if so, the details of those practices. Aside from wake-up time, the survey asked about the “number of nocturnal awakenings” and the “ability to wake at a predetermined time” as indicators of the ability to get up in the morning. Frequency of consuming breakfast, lunch, and dinner was rated on a 4- point scale of “almost every day”, “4 to 5 days a week”, “around 2 to 3 days a week”, and “almost never”. Snacking was rated on a 5-point scale, from “five to six times per week”, “three to four times per week”, “one to two times per week”, “one to three times a month”, and “almost never”. Waking ability was rated on a 4-point scale of “easy”, “possible with some effort”, “possible with high effort”, and “cannot wake”.
2.2.3. Health Maintenance Ability
The study used the 13-items (Japanese) version of Antonovsky’s SOC questionnaire created by Yamazaki et al. [12]. The total score of the 7-point scale items was used as the SOC score. High scores indicated a high SOC. In both men and women, those with an SOC score above the median were said to have a high SOC. Those with scores below the median were designated as having a low SOC.
2.3. Statistical Analysis
Numeric data are represented by mean and standard deviation (SD). Student’s t-test was performed on selfrated health item, each satisfaction level, and SOC total scores. A 2 × 2 Fisher’s exact test and a 2 × M MannWhitney’s U test were conducted for the dichotomized SOC levels. SPSS ver. 15 (SPSS Japan Inc, Tokyo, Japan) was used for analysis. All tests were two-tailed, and significance levels were set at p < 0.05.
3. RESULTS
We analyzed the data of all 618 respondents (412 women, 206 men) from whom complete valid responses were obtained. All respondents resided in greater Tokyo or surrounding areas and were regular full-time employees. Age and SOC are shown in Table 1. No significant differences in age or SOC were detected between men and women. Survey reliability was confirmed with a Cronbach’s alpha of 0.856 for SOC.
Table 2 shows the relationship between SOC and selfrated health, satisfaction, and stress. Self-rated health and level of satisfaction were significantly higher and the level of stress experienced on a daily basis was significantly lower in men and women with high SOC.