2.3. Measures

Flourishing. Under the advisement of Keyes, the flourishing scale was constructed of two parts: (1) happiness and satisfaction in life; and (2) positive psychological functioning.

The first part of the flourishing scale was measured by an affirmative response to either of the questions. The first question was “would you describe yourself as being usually happy and interested in life” with five response options (happy and interested in life, somewhat happy, somewhat unhappy, unhappy with little interest in life, and so unhappy that life is not worthwhile). Respondents who indicated “happy and interested in life” were recoded as 1; otherwise they were recoded as 0. The second question “Is doing the things you do every day a source of great pleasure and satisfaction or a source of pain and boredom?” was originally measured as an ordinal variable on a scale of one to seven, where one indicated “a great deal of pleasure and satisfaction” and seven indicated “a source of pain and boredom”. We recoded scores of one or two to “1 = pleasure and satisfaction” and scores of three to seven to “0 = not a source of pleasure and satisfaction”. The second part of the flourishing scale was measured by affirmative responses to at least five out of eight of the following questions. The first question “Until now your life has had no clear goals or purpose, or has it had very clear goals and purpose?” had a seven-point response scale anchored at 1 “no clear goals or no purpose” and 7 “very clear goals and purpose”. The second question “When something happens, you generally find that you overestimate or underestimate its importance or you see things in the right proportion?” had a seven-point scale with 1 anchored at “overestimate or underestimate its importance” and 7 “see things in the right proportion”. People who scored six or seven were recoded as “1 = positive psychological functioning”, while people who scored one to five were recoded as “0 = negative psychological functioning”. The remaining six questions: “You feel that you have a number of good qualities”, “You feel that you're a person of worth at least equal to others”, “You are able to do things as well as most other people”, “You take a positive attitude toward yourself”, “On the whole you are satisfied with yourself” and “You can do just about anything you really set your mind to”, were originally measured on a five-point Likert scale ranging from “strongly agree” to “strongly disagree”. For each question, we recoded scores of 1 or 2 as “1 = positive psychological functioning” and scores of 3 to 5 as “0 = negative psychological functioning”.

The Cronbach's alpha reliability coefficient of the flourishing scale, based on the 10 items, was 0.7, indicating acceptable internal consistency. Confirmatory factor analysis was conducted to examine the factor structure of the flourishing scale using Mplus 8. A single-factor model showed acceptable fit with the data (RMSEA = 0.054; TLI = 0.914; CFI = 0.933). The chi-square test was statistically significant (χ ² = 1353, p < .001), however, the chi-square test is sensitive to sample size and tends to be significant for models with more than 200 cases. Regarding discriminant validity, we found at baseline that respondents without flourishing mental health had a higher percentage of MDE (16.8%) compared to those who had flourishing mental health (3.4%). A dichotomous flourishing indicator was created to identify people who were happy and satisfied in life and had good psychological functioning at baseline (1994–1995), in contrast to those with suboptimal mental health.

All-cause mortality. Mortality was ascertained by the Canadian Vital Statistics-Death Database in the NPHS. We subtracted the month and year of death from the month of interview in 1994 or 1995 to generate the time in months to mortality. Predictors of all-cause mortality. Drawing on previous empirical studies, the following variables were used as potential risk factors that may affect the probability of mortality in later life. All the predictors included in the study were measured at baseline.

Sociodemographic characteristics. Gender (male vs. female) and ethnicity (white vs. non-white) were coded as dichotomous variables. Age was coded into six groups: 18–29 years, 30–39 years, 40–49 years, 50–59 years, 60–69 years, 70 years or older. Marital status was measured as a categorical variable, into single, widowed/divorced/separated, and married/common-law/partner. Education was measured as an ordinal variable with four levels: less than secondary, secondary, some post-secondary, and post-secondary graduation. Income was measured based on the ranking of household income, which was categorized into five quintiles: highest quintile, fourth quintile, middle quintile, second quintile, and lowest quintile.

Pain and functioning. Pain was measured as a dichotomous variable (yes/no) based on response to the question, “Are you usually free of pain or discomfort?” Functional limitations (yes/no) was measured by an affirmative response to a derived variable “Restriction of activity excluding long-term disabilities or handicaps” provided by the NPHS survey.

Health behaviors. Obesity (normal, underweight, overweight, or obese), smoking status (never smoker, former smoker, or current smoker), and level of physical activity (regular, occasional, or infrequent) were included. Heavy drinking was measure as a dichotomous variable with “1 = women who have eight or more drinks per week and men who have 15 or more drinks weekly” versus “0 = those who drink less (not heavy drinker)”.

Social support. Social support was measured as a dichotomous variable based the question, “Do you have someone you can confide in or talk to about your private feelings or concerns?”

Chronic illness. Eight types of physical chronic illness were included in this study: asthma, high blood pressure, chronic bronchitis, diabetes, heart disease, cancer, stroke, and other long-term condition. Each chronic illness was measured by an affirmative answer to the question, “Do you have any of the following long-term conditions that have been diagnosed by a health professional?”. We also included a dichotomous measure of previous 12-month MDE at baseline by assessing the Composite International Diagnostic Interview-Short Form (CIDI-SF) in the NPHS. MDE was defined as a 90% predictive probability of the CIDI-SF algorithm in NPHS. The 90% cut-point has been validated against the DSM-III-R diagnosis for MDE [³⁵].