Impact of the obesity paradox on 28-day mortality in elderly patients critically ill with cardiogenic shock: a retrospective cohort study.

Background: Previous studies have shown that the obesity paradox exists in cardiovascular disease (CVD), giving patients a survival advantage, but controversy remains as to whether it applies to patients with cardiogenic shock (CS), especially in the elderly. We therefore aimed to determine whether obesity affects 28-day prognosis in elderly patients with CS.

Methods: We used clinical data from the Medical Information Market in Critical Care IV (MIMIC-IV) database. Critical patients with CS were categorized into two groups based on age; age < 65 years and ≥ 65 years were classified as young adult patients and elderly patients, respectively. Patients were then categorized into two subgroups based on their body mass index (BMI), one with a BMI ≥ 30 kg/m² and the other with a BMI < 30 kg/m². The primary outcome was a 28-day prognosis. Secondary outcomes were mechanical ventilation status, length of hospitalization, and length of ICU stay.

Results: 1827 patients from the MIMIC-IV ICU database were analyzed, of which 571 patients were < 65 years old and 1256 patients were ≥ 65 years old. According to multifactorial logistic analysis, BMI > 30 kg/m² was not a 28-day risk factor for death in elderly patients critically ill with CS (Overweight OR 1.28, P = 0.221; Obesity OR 1.15, P = 0.709; Severe obesity OR 1.46, P = 0.521; using normal weight as a reference). In contrast, underweight was a risk factor (OR 2.42, P = 0.039). Kaplan-Meier curves showed that in the older age group, 28-day survival was significantly higher in patients with BMI ≥ 30 kg/m² compared to those with BMI < 30 kg/m² [261 (66.75%) vs. 522 (60.35%), P = 0.024].

Conclusion: Underweight affects the 28-day prognosis of critically ill elderly patients with CS. In contrast, overweight and or obesity do not appear to have a significant impact on the prognosis of these patients.