Socioeconomic inequality in lifestyle trajectories among middle-aged and older adults: A 10-year longitudinal analysis across the US, UK and China.

BACKGROUND: Health-related lifestyles may change throughout the life course and are often socially patterned. However, few studies have identified the association of socioeconomic status with the longitudinal patterns of lifestyle trajectories. This study aimed to identify lifestyle trajectories among middle-aged and older adults across multiple regions, and examine whether these trajectories differed by socioeconomic status.

METHODS: In this multi-cohort study, individual-level data were pooled from three longitudinal studies: the Health and Retirement Study in the US, the English Longitudinal Study on Ageing in the UK, and the China Health and Retirement Longitudinal Study in China. Lifestyle scores were constructed using smoking status, alcohol consumption, physical activities, and sleep quality. Socioeconomic status scores were based on education level and total household income. Group-based trajectory modeling was used to identify participants' lifestyle trajectories over 10 years. The associations between socioeconomic status and lifestyle trajectories were evaluated using multinomial logistic regression models.

RESULTS: Of the 27,401 participants, 16,325 were from the US, 4683 from the UK, and 6393 from China. Three lifestyle trajectories over 10 years were identified: 'stable high', 'stable medium', and 'stable low'. Participants with low socioeconomic status were at higher odds of belonging to the 'stable low' group, with an odds ratio (OR) of 1.86 (95 % confidence interval [CI] 1.66-2.09), 1.38 (95 % CI 1.12-1.70) and 1.84 (95 % CI 1.45-2.34) in the US, UK and Chinese participants, respectively. Study-specific meta-analysis showed similar associations between socioeconomic status and lifestyle trajectories, with an OR of 1.69 (low vs high socioeconomic status; 95 % CI 1.40-2.05) and 1.18 (middle vs high socioeconomic status; 95 % CI 1.04-1.34).

CONCLUSION: Lifestyle trajectories remained stable over 10 years, and lower socioeconomic status was associated with higher odds of belonging to the 'stable low' group. Early-life interventions to minimize socioeconomic inequality should be prioritized to promote sustainable healthier lifestyles in later life.