Predictors of favorable and poor prognosis in unwitnessed out-of-hospital cardiac arrest with a non-shockable initial rhythm.

BACKGROUND: Unwitnessed OHCA patients with non-shockable initial rhythms account for nearly half of all OHCA patients, and their prognosis is extremely poor. To date, no studies have focused on these patients. This study aimed to investigating the predictors of favorable and poor prognosis in these patients.

METHODS: We conducted a nationwide, population-based, observational study of data from the All Japan Utstein Registry, which included 121,081 adult OHCA patients subjected to resuscitation attempts from January 1, 2010 to December 31, 2010. The primary endpoint was favorable neurological outcome one month after OHCA.

RESULTS: Of the eligible 120,721 patients, 68,024 (56.3%) were unwitnessed OHCA patients with non-shockable initial rhythms. A younger age (18-64 years: as a reference; 65-84 years: OR 0.68, 95% CI 0.54-0.87, p=0.0019; ≥85 years: OR 0.46, 95% CI 0.33-0.63, p<0.0001), conversion to shockable rhythm (OR 2.14, 95% CI 1.43-3.13, p=0.0003), and pre-hospital ROSC (OR 94.85, 95% CI 75.71-119.35, p<0.0001) were independently associated with a favorable neurological outcome. Favorable neurological outcome rate was 28.8% in unwitnessed OHCA patients with non-shockable initial rhythms with all three favorable predictors, and 0.18% in patients without any of the three predictors (OR 230.34, 95% CI 127.37-402.96, P<0.0001).

CONCLUSIONS: It may be worthwhile to provide maximum lifesaving medical resources for patients with all of the favorable predictors (<65 years, conversion to shockable rhythm, and pre-hospital ROSC); however, continued resuscitation efforts for patients without these predictors should likely be restrained.