How frailty and nursing complexity interact and prolong hospital stays in heart failure patients: a retrospective multicentric observational study

• Frailty is positively correlated with nursing complexity in hospitalized patients with heart failure. • Frailty and nursing complexity show weak but consistent associations with length of stay. • Latent admission profiles of frailty and nursing complexity can be identified using routinely collected data. • A high frailty/high nursing complexity profile is independently associated with prolonged length of stay. This study aimed to examine frailty and nursing complexity at hospital admission in patients with heart failure (HF) and to explore their individual and joint associations with length of stay (LOS). A retrospective multicentric observational study was conducted among adult patients with HF admitted to two Italian university hospitals between January 1 and December 31, 2022. Frailty was estimated using the Blaylock Risk Assessment Screening Score (BRASS), while nursing complexity was measured by the number of nursing diagnoses (NDs) at admission. Prolonged LOS was defined as hospital stays exceeding the 75th percentile. Data were extracted from the hospital discharge register and the Professional Assessment Instrument and analyzed using correlation analyses, latent class analysis (LCA), and logistic regression models. Among 1712 patients, 26.6% experienced prolonged LOS. Frailty was positively associated with nursing complexity ( r = 0.245, 95% CI: 0.196–0.288), and both frailty (r s = 0.236; 95% CI: 0.192–0.281) and nursing complexity (r s = 0.232; 95% CI: 0.187–0.278) were associated with LOS. LCA identified two admission profiles: low frailty/low nursing complexity and high frailty/high nursing complexity. Membership in the high frailty/high nursing complexity profile was associated with higher odds of prolonged LOS in unadjusted model (OR = 2.805, 95% CI: 2.223–3.541; p < 0.001), and remained significant after adjustment for age, sex, comorbidities, and DRG weight (OR = 1.939, 95% CI: 1.354–2.776; p < 0.001). Joint assessment of frailty and nursing complexity at hospital admission may support early identification of HF patients at risk for prolonged LOS.