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

Abstract 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 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 was not a 28-day risk factor for death in elderly patients critically ill with CS (Overweight OR 1.18, P = 0.271; Obesity OR 1.05, P = 0.770; Severe obesity OR 1.06, P = 0.839; using normal weight as a reference). In contrast, underweight was a risk factor (OR 2.02, P = 0.033). Kaplan-Meier curves showed that in the older age group, 28-day survival was significantly higher in patients with BMI ≥ 30 compared to those with BMI < 30 [ 261 (66.75%) vs. 522 (60.35%), P = 0.024]. Conclusion The obesity paradox does not seem to apply to patients with CS, whether young or elderly, but rather underweight can have an impact on the 28-day prognosis of elderly patients who are critically ill with CS.