Living Alone as a Persistent Risk Factor for Smoking and High-Risk Drinking: A Three-Year Repeated Cross-Sectional Analysis Before and During the COVID-19 Pandemic in the Republic of Korea.

Publication date: May 06, 2026

Background: Single-person households have grown rapidly in the Republic of Korea and are consistently associated with higher rates of smoking and high-risk drinking. However, it remains unclear whether this vulnerability is structural and chronic or merely situational. This study examined whether the COVID-19 pandemic-a major societal disruption-altered the preexisting behavioral gap between single- and multi-person households. Methods: We used repeated cross-sectional data from the Korea Community Health Survey (KCHS) for 2019 (unweighted n = 229,099), 2020 (unweighted n = 229,269), and 2021 (unweighted n = 229,242), representing weighted populations of approximately 43. 0, 43. 5, and 43. 6 million adults aged ≥19 years, respectively. We applied complex sample logistic regression models including an interaction term between survey year and household type, adjusting for sex, age, income, and education. Results: High-risk drinking significantly declined in both household types across all three time points following the COVID-19 pandemic, whereas smoking showed no significant overall change. Critically, the year x household type interaction was non-significant for high-risk drinking across all years; for smoking, a marginally significant interaction emerged only in 2021 (adjusted odds ratio [AOR] = 1. 08, 95% CI: 1. 01-1. 16), suggesting a slight but limited divergence in the later pandemic period. Single-person households consistently showed higher odds of smoking (AOR = 1. 65, 95% CI: 1. 56-1. 74) and high-risk drinking (AOR = 1. 32, 95% CI: 1. 25-1. 39) across all three time points, relative to multi-person households and referenced to 2019 as the pre-pandemic baseline. Conclusions: The health behavioral vulnerability of single-person households is structural and persistent, underscoring the need for household-structure-sensitive public health strategies to promote sustainable well-being.

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