Appendix 2. Estimating the Effects of Interactions Between the Genetic Variant and the Fixed Exposure on Longevity Following the FAD Approach: Social and family support and village or on the same street, vs those who had neither co-resident children nor children living nearby). We also examined social support, which was measured by a question that asked participants based on frequency of participation in seven activities: personal hobbies like gardening and/or pets, playing cards or mah-jong, participating in organizational activities, reading newspapers and books, and watching TV and listening to the radio. Results ranged from 0 to 7.

Gene-fixed exposure interactions on survival from age x to x + n, using the ORs of survival (RS, i = 0,1; j = 0,1) derived by Formula (2). On a multiplicative scale, the Interaction Index of Survival (ISm) is estimated as:

On an additive scale, the Interaction Index of Survival (ISa) is estimated as:

If ISm or ISa is significantly greater or less than 1, the interaction between the genetic variant and the fixed exposure positively or negatively affects survival from age x to x + n.

The resilience score: The resilience score was constructed based on the more straightforward and simplified definition of resilience specified in Lamond and colleagues (34), namely, resilience connotes the ability to adapt positively to adversity (i.e. ability of coping and adjustment). We selected seven available and relevant items in the demographic study CLHLS to construct the resilience score, which is actually a simplified version (focusing on coping and adjustment) of the resilience index used in the in-depth psychological study (35).

The Deficits Index: The Deficits Index is used as a proxy for biological age, as a predictor of health change, and utilization of health services and has been posited to capture the cumulative deficits of the same. Based on 39 variables that include cognitive function, instrumental activities of daily living, activities of daily physical performance functional limitations, interviewer-reported health, hearing loss, and vision in the past 2 years, and reports of specific chronic in the past year for which a score of 2 was given if the number used to construct the DI is available elsewhere (37).

Health practices: Cigarette smoking was assessed by the following question: Do you smoke regularly at the present time? Response options were no (coded 0) and yes (coded 1). Based on relatively detailed information concerning the frequency, quantities, and types of alcohol consumed, we coded participants as heavy alcohol drinkers (defined as having at least 200g of liquor or 400g of beer per day) (code=1) versus not heavy alcohol drinkers (code=0). Exercise was assessed by the following question: Do you exercise regularly at present time? Response options were yes and no, coded 1 and 0 respectively.

The frequency distributions of the 15 covariates included in our Cox proportional hazards regression models are not presented in this article due to space limitation and are available upon request.