An epidemiologic study is conducted to evaluate the long-term complications of coronary stent placement. 10,000 patients who underwent emergency or elective percutaneous coronary intervention at tertiary care centers around the nation were randomly selected and monitored for the development of adverse events. According to the study results, 2% of patients who received bare metal stents developed stent thrombosis within a year. 40% of the patients who developed stent thrombosis died as a result. The risk of death in a patient who develops stent thrombosis is best described by which of the following epidemiologic parameters?
A)Attack rate
B)Case fatality rate
C)Median survival time
D)Mortality rate
E)Standardized mortality ratio

Question

An epidemiologic study is conducted to evaluate the long-term complications of coronary stent placement.  10,000 patients who underwent emergency or elective percutaneous coronary intervention at tertiary care centers around the nation were randomly selected and monitored for the development of adverse events.  According to the study results, 2% of patients who received bare metal stents developed stent thrombosis within a year.  40% of the patients who developed stent thrombosis died as a result.  The risk of death in a patient who develops stent thrombosis is best described by which of the following epidemiologic parameters?
A)Attack rate
B)Case fatality rate
C)Median survival time
D)Mortality rate
E)Standardized mortality ratio

Quizplus · Accepted Answer

Explanation: The case fatality rate (CFR) refers to the proportion of people with a particular condition who end up dying from the condition. In this scenario, only 2% of patients who received a bare metal stent developed stent thrombosis. However, 40% of the patients with stent thrombosis ended up dying from it. Therefore, the CFR in this situation is 40%. CFR should be distinguished from the mortality rate, which refers to the probability of dying from a particular disease in the general population (Choice D). In the above example, the mortality rate for stent thrombosis would be much smaller than the CFR for stent thrombosis, as the majority of the general population would not even undergo percutaneous coronary intervention. (Choice A) The attack rate is defined as the proportion of people in whom an illness develops out of the total population at risk for the disease. In this example, the attack rate for stent thrombosis in patients with bare metal stent placement is 2% per year. (Choice C) Median survival time is a measure of prognosis when studying large groups. It is defined as the length of time that it takes for half of the study population to die. (Choice E) Standardized mortality ratios are used to determine if the observed number of deaths in a group exceeds what would be expected in a similar group (eg, similar age, gender) excluding the variable of interest (eg, smoking status, cholesterol levels). They are calculated using mortality rates for the general population to determine the number of expected deaths, which are then compared to the observed number of deaths. Educational objective: Case fatality rate refers to the proportion of patients with a particular disease who die from the disease. It is different from the mortality rate, which describes the general population's likelihood of dying from the disease.

An Epidemiologic Study Is Conducted to Evaluate the Long-Term Complications