Correlates of hospitalization among the oldest old: results of the AgeCoDe-AgeQualiDe prospective cohort study

BACKGROUND: Hospitalization is a key driver of health care costs. Thus far, there are only a few longitudinal studies investigating whether changes in explanatory variables lead to hospitalization. Moreover, these longitudinal studies did not focus on individuals in highest age.

AIM: The purpose of the current study was to examine the correlates of hospitalization among the oldest old in Germany longitudinally.

METHODS: A multicenter prospective cohort study ["Study on Needs, health service use, costs and health-related quality of life in a large sample of oldest-old primary care patients (85+)", AgeQualiDe]. Primary care patients ≥ 85 years took part [n = 861 at follow-up (FU) 7, average age of 89.0 years; 85-100 years]. Two waves were used. Hospitalization in the last 6 months was used as outcome measure. Well-established scales were used to quantify the independent variables such as Instrumental Activities of Daily Living Scale, Global Deterioration Scale or Geriatric Depression Scale.

RESULTS: Logistic random effects regressions showed that the probability of hospitalization in the preceding 6 months significantly increased with increases in the social network, more depressive symptoms, functional decline, and increase in chronic conditions, whereas it was not significantly associated with age, sex, marital status, education, and cognitive impairment. Social networks moderate the relationship between functional decline and hospitalization.

DISCUSSION: The results of the present longitudinal study emphasize the association of depressive symptoms, functional decline, more social networks, and chronic conditions with hospitalization among the oldest old.

CONCLUSIONS: Treatments with the aim to reduce or postpone these factors might also help to reduce hospitalization.