Association between body mass index and survival outcomes for in-hospital cardiac arrest

Body mass index (BMI), a key clinical marker, may influence outcomes after in-hospital cardiac arrest (IHCA), but its association with neurologically favorable survival remains unclear.

Within Get With The Guidelines®-Resuscitation, we analyzed 56,411 IHCA patients with BMI data during 2006-2012. BMI was classified as underweight (<18.5 kg/m²), normal (18.5-24.9), overweight (25.0-29.9), obese (30.0-34.9), and very obese (≥35.0). Multivariable hierarchical models with hospital as a random effect assessed the association between BMI and favorable neurological survival (discharge cerebral performance category score of 1) and survival to discharge.

Among 10,219 patients with a shockable rhythm, 3014 (29.4%) had favorable neurological survival, and 3,964 (38.7%) survived to discharge. After adjustment, compared with normal BMI patients, underweight patients had lower favorable neurological survival (OR 0.64 [95%CI: 0.49-0.84]), while overweight (OR 1.17 [1.04-1.33]) and obese (OR 1.16 [1.00-1.34]) patients had higher rates of favorable neurological survival; no difference was seen for very obese patients (OR 1.06 [0.91-1.24]). A similar pattern was observed for survival to discharge. Among 46,192 patients with a non-shockable arrest rhythm, 4844 (10.4%) had favorable neurological survival, and 7,331 (15.8%) survived to discharge. After adjustment, all BMI groups had similar rates of favorable neurological survival and survival to discharge, except for underweight patients (OR 0.76 [0.66-0.89] and 0.85 [0.75-0.95], respectively).

For patients with IHCA, underweight patients had lower rates of survival and favorable neurological survival, regardless of initial cardiac arrest rhythm. In contrast, overweight and obese patients had better outcomes only when the initial rhythm was shockable.