Cardiac Arrest Researchers conducted a prospective cohort study in which male patients who had an out-of-hospital cardiac arrest were submitted to therapeutic hypothermia (intravenous infusion of cold saline followed by surface cooling with the goal of maintaining body temperature of 33 degrees Celsius for 24 hours. Note that normal body temperature is 37 degrees Celsius). The survival status, length of stay in the intensive care unit (ICU), and time spent on a ventilator were measured. Each of these variables was compared to a historical cohort of patients who were treated prior to the availability of therapeutic hypothermia. Of the 52 hypothermia patients, 37 survived; of the 74 patients in the control group, 43 survived. The median length of stay among survivors for the hypothermia patients was 14 days versus 21 days for the control group. The time on the ventilator among survivors for the hypothermia group was 219 hours versus 328 hours for the control group.


f. Based on the results of this study, what is the probability a randomly selected male who has an out-of-hospital cardiac arrest and submits to therapeutic hypothermia will survive? What about those who do not submit to therapeutic hypothermia?

Verified step by step guidance

1. Identify the total number of patients who received therapeutic hypothermia and the number of survivors in that group. Here, the total is 52 patients, and 37 of them survived.
2. Calculate the probability of survival for the therapeutic hypothermia group by dividing the number of survivors by the total number of patients in that group. Use the formula: \(\text{Probability of survival} = \frac{\text{Number of survivors}}{\text{Total number of patients}}\).
3. Identify the total number of patients in the control group (those who did not receive therapeutic hypothermia) and the number of survivors in that group. Here, the total is 74 patients, and 43 of them survived.
4. Calculate the probability of survival for the control group by dividing the number of survivors by the total number of patients in that group, using the same formula as above.
5. Interpret these probabilities as the likelihood that a randomly selected male patient with out-of-hospital cardiac arrest will survive given whether or not they receive therapeutic hypothermia.

Key Concepts

Probability

Probability measures the likelihood of an event occurring, expressed as a number between 0 and 1. In this context, it represents the chance that a patient survives after cardiac arrest under different treatments. It is calculated by dividing the number of survivors by the total number of patients in each group.

Prospective Cohort Study

A prospective cohort study follows a group of individuals over time to observe outcomes based on exposure to a treatment or risk factor. Here, patients receiving therapeutic hypothermia were followed to assess survival, compared to a historical control group, allowing comparison of outcomes between treated and untreated groups.

Comparative Analysis of Groups

Comparative analysis involves evaluating differences in outcomes between two or more groups. This study compares survival rates and other clinical measures between hypothermia-treated patients and a control group, helping to determine the effect of the treatment on patient outcomes.