Comparison of Psychosocial Variables Associated With Loneliness in Centenarian vs Elderly Populations in New Zealand

IMPORTANCE: Loneliness is associated with reduced health-related quality of life and increased morbidity and mortality and typically worsens with aging. OBJECTIVES: To evaluate associations between demographic and psychosocial variables and loneliness, examine any age-specific associations, and compare centenarians (aged ≥100 years) with elderly people (aged 65-99 years). DESIGN, SETTING, AND PARTICIPANTS: In this retrospective, observational, cross-sectional study, previously collected data from all New Zealanders 65 years and older who completed their first international Resident Assessment Instrument–Home Care (interRAI-HC) assessment during the study period (January 1, 2013, to November 27, 2017) were reviewed. Participants were people living independently in the community who were requesting or referred for assessment with a potential need for support services. MAIN OUTCOMES AND MEASURES: The interRAI-HC is a 236-item, electronically recorded assessment that encompasses a comprehensive range of aspects of an older person’s life, including physical, psychological, and cognitive domains. Eight main items from the interRAI-HC data set were analyzed to describe the population and evaluate the core psychosocial components of aging, namely, age, sex, race/ethnicity, marital status, living arrangements, family support, depression, and loneliness. Loneliness was evaluated by the participants’ response to the assessment statement, “Says or indicates that he/she feels lonely.” RESULTS: A total of 73 286 New Zealanders (mean age, 81.4 years; age range, 65-109 years; 41 641 [56.9%] female) participated in the study. The assessments of 191 centenarians (mean [SD] age, 100.9 [1.2] years) and 73 095 elderly people (mean [SD] age, 81.4 [7.6] years) were analyzed. Centenarians vs elderly people were more likely to be female (136 [71.2%] vs 41 488 [56.8%]; P < .001), and the populations differed by marital status (widowed: 170 [89.0%] vs 31 554 [43.2%]; overall P < .001) and depression status (70.2% vs 59.5% free of depression; overall P = .008). Centenarians were less likely to be lonely compared with elderly people, with a 22% lower risk of loneliness for a typical centenarian (aged 100.9 years) compared with a typical elderly person (aged 81.4 years) in unadjusted analyses (relative risk, 0.78; 95% CI, 0.67-0.92; P = .002). In the fully adjusted model, there was a 32% reduction in loneliness for a centenarian compared with an elderly person (relative risk, 0.68; 95% CI, 0.58-0.79; P < .001). Living with others, having family support, and lacking depression were associated with lower risk of loneliness. CONCLUSIONS AND RELEVANCE: Centenarians are a unique group to study as a model of successful aging. The sample of centenarians in this study appeared to be less lonely than other groups studied internationally. The study identified multiple psychosocial variables that were associated with the risk of loneliness, including living arrangements, family support, and depression. Knowing these variables may help our society address risk factors for loneliness in older people.