Couple-level metabolic phenotypes and self-rated health in Korean adults

Self-rated health (SRH) is a widely used indicator of overall health and a robust predictor of morbidity and mortality. Although metabolic health and obesity are well-established determinants of SRH, most previous studies have examined these factors at the individual level. This study investigated how spousal metabolic phenotypes, defined by metabolic and weight status, are jointly associated with SRH among Korean adults.

We analyzed nationally representative data from 1817 heterosexual couples. Participants were classified into four phenotypes: metabolically healthy normal weight (MHNW), metabolically healthy obesity (MHO), metabolically unhealthy normal weight (MUNW), and metabolically unhealthy obesity (MUO). We applied actor-partner interdependence models (APIM) and couple-level analyses to assess associations with worse SRH, adjusting for sociodemographic factors, health behaviors, perceived stress, and comorbidities.

Among husbands, the MUNW phenotype was significantly associated with worse SRH, with marginal partner effects were observed when wives were MUNW. Among wives, both MUNW and MUO were significant predictors of worse SRH, whereas partner effects were not significant. At the couple level, husbands had higher odds of worse SRH across all non-MHNW couple combinations, whereas wives had higher odds only in discordant couples in which the wife was non-MHNW and the husband was MHNW. Sensitivity analyses among older couples confirmed these findings.

These findings highlight gender-specific actor and partner effects and suggest that couple-level metabolic profiles may shape SRH, underscoring the importance of considering spousal metabolic status in its assessment.