Multimorbidity patterns and hospitalizations due to lower respiratory tract infections: a 15-year population-based cohort study

Background: Lower respiratory tract infections (LRTIs) are common among older adults and are associated with high healthcare utilization, particularly in those with multimorbidity (≥2 chronic conditions). We aimed to investigate the association between different multimorbidity patterns and LRTI-related hospitalizations. Materials and methods: We used data from the population-based Swedish National study on Aging and Care in Kungsholmen (SNAC-K). Latent class analysis was applied to participants with multimorbidity to identify multimorbidity patterns. A disease was considered to characterize a pattern if exclusivity was ≥25% or the observed/expected ratio was ≥2. Cox regressions were used to estimate hazard ratios (HRs) for the association between multimorbidity patterns and [1] LRTI-related hospitalizations and [2] all-cause 30-day readmission, compared with participants without multimorbidity. Results: Among the 3301 study participants, 2931 (87.5%) had multimorbidity, and over a median follow-up of 14 years, 412 (12.5%) were hospitalized with an LRTI and 152 (4.5%) experienced a 30-day readmission. Five multimorbidity patterns were identified. The cardiometabolic pattern showed the highest hazards for LRTI-related hospitalizations and 30-day readmissions, followed by the psychiatric/respiratory pattern. The neuropsychiatric pattern was associated with increased hazard of 30-day readmissions. Conclusions: Multimorbidity patterns are differentially associated with LRTI-related hospitalizations and 30-day readmissions, suggesting that the link between LRTIs and multimorbidity patterns is complex and reflects the specific burden of diverse multimorbidity patterns.