Disutility associated with social isolation and loneliness in Germany: results of a population survey using the EQ-5D-5L instrument.

Background: Social isolation and loneliness are highly prevalent and may have a negative impact on health-related quality of life (HRQL). The EQ-5D-5L is a widely used questionnaire from which an index value for HRQL based on societal preferences (utility) can be derived. The purpose of this study was to estimate the loss in utility (i.e. disutility) associated with loneliness and social isolation in the German adult population.

Methods: Data came from a quota sample of individuals aged 18-74 years residing in Germany (n = 5,000) and representing the adult population in terms of age groups, gender and geographic locations. Data collection was conducted online in August and September 2023 by a certified market research firm. The EQ-5D-5L index score based on the German value set was used as outcome. Moreover, the established Lubben Social Network Scale was used to measure social isolation. The De Jong Gierveld tool was used to quantify loneliness. Groups affected by social isolation or loneliness were compared to non-affected groups, respectively. Differences in covariates between affected and non-affected groups were balanced using entropy balancing. Linear regressions were conducted afterwards (using the weights derived from the entropy balancing). Subgroup analyses by sex and age groups as well as various robustness checks were conducted.

Results: The EQ-5D-5L index score was lower among individuals with social isolation compared to individuals without social isolation (β=-0.04, p < 0.001). Moreover, the EQ-5D-5L index score was lower among individuals with loneliness compared to individuals without loneliness (β=-0.07, p < 0.001). Several robustness checks produced similar results. The findings were almost the same for both women and men and varied only slightly between age groups.

Conclusions: We found a statistically significant and relevant disutility associated with social isolation and, even more pronounced, with loneliness. The magnitude of disutilities is similar to those reported for various chronic diseases. Taking into account the high prevalence of social isolation and, in particular, loneliness, the associated burden in terms of quality-adjusted life years (QALY) lost is likely to be tremendous. The results underline the need to take action against the high prevalence of loneliness and social isolation.