Factors related to 30-day survival rate following accidental hypothermia - a retrospective single-center study from Northern Finland.

BACKGROUND

Accidental hypothermia is a rare condition, and it is reported to cause 2-5 deaths per 100,000 in European studies and at least 1,500 deaths in the United States annually. There is limited evidence concerning concomitant factors, clinical findings, prehospital care, and treatment methods related to patients who experience accidental hypothermia.

METHODS

This is a retrospective registry study with data consisting of patients over 18 years of age who were admitted to Oulu University Hospital in Finland with accidental hypothermia. Data were collected for 12 years (2008-2019). Patients were divided into survivors and non-survivors according to their 30-day survival.

RESULTS

Of 315 initial patients, 241 were included in the final analysis: 206 survivors and 35 non-survivors. Alcohol abuse was the most common concomitant factor (49%), followed by age ≥ 65 years (42%). Indoor exposure was the most common etiology among non-survivors while outdoor exposure was most common among survivors (37% vs. 64%, p < 0.001). Daytime EMS dispatch was associated with higher mortality than nighttime dispatch (18% vs. 3%, p = 0.007). Lower recorded temperatures on the scene (27.0 °C vs. 30.1 °C) and in the emergency department (27.4 °C vs. 31.9 °C) were associated with decreased survival rate (p < 0.001 for both). Overall 30-day mortality was low (15%) and survival after cardiac arrest was high (47%). According to multivariable logistic regression analysis for concomitant factors and hypothermia etiology, submersion (odds ratio 0.27, p = 0.038) and trauma (odds ratio 0.32, p = 0.084) decreased the chance of 30-day survival.

CONCLUSIONS

Alcohol abuse and age ≥ 65 years were two of the most common concomitant factors for accidental hypothermia. Non-survivors were generally older and more likely to be found indoors. They were most often found during daytime hours, and their recorded temperature was generally lower. Submersion and trauma were independent risk factors for mortality.