Individual and spousal weight trajectories and their associations with health-related quality of life: a longitudinal population-based cohort from the Tehran Lipid and Glucose Study (2001-2018).

backgroundAlthough the association between obesity and health-related quality of life (HRQoL) is well-documented, studies on the association between weight trajectories and HRQoL among spouses are limited. This longitudinal study aimed to characterise distinct body mass index (BMI) trajectories and their association with HRQoL at individual and spousal levels.

methodsThe total sample of 773 couples was followed for an average of 15 years. Univariate group-based trajectory models and multi-trajectory group-based models were used to identify latent classes of individual and couple BMI trajectories, respectively. Linear regression analyses were applied to investigate the associations between identified BMI trajectories and HRQoL at the individual level and at the spousal level, where spousal HRQoL refers to the association between both partners' BMI trajectories and each individual's HRQoL.

resultsBased on BMI changes over the life course, four trajectories were identified in wives and husbands at both individual and couple levels, ranging from stable healthy weight to progressively increasing overweight and obesity, with all trajectories showing an overall rise in BMI with age. In the fully adjusted model, compared with wives in the mild progressive overweight group, the mean score of physical HRQoL in women in the progressive obesity group (β=-2.14, p=0.02) and severe progressive obesity group (β=-2.55, p=0.03) was significantly lower. Moreover, compared with husbands with stable healthy weight status, those in the progressive obesity group had lower physical HRQoL (β=-2.67, p=0.02). At the spousal level, lower physical HRQoL was observed in individuals whose BMI trajectories, together with their partner's trajectory, indicated higher risk (eg, wives with severe progressive obesity and husbands with stable overweight) compared with couples with both partners in lower-risk BMI trajectories (β=-3.61, p=0.01). A similar effect was observed only in severe progressive obese women whose husbands were of stable healthy weight during their lifespan. None of the BMI trajectories at either individual or spousal levels affected mental HRQoL.

conclusionOur findings indicate a significant effect of individuals' BMI patterns on the physical domain of HRQoL. Spousal HRQoL associations reflect how both partners' BMI trajectories are jointly associated with individual HRQoL. Clinically, these results highlight the potential importance of early weight management, particularly in women, in relation to long-term physical HRQoL and possible benefits for both partners. Further investigation is required to assess the role of potential confounders in BMI-HRQoL associations.