The abstract applies to the next 2 items.Over the course of 5 years, a pediatric endocrinologist has seen a marked increase in the prevalence of depression among patients with obesity in her practice. She partners with a pediatric psychiatrist to devise a short screening test for depression for this specific population. The new screening test is found to be 90% sensitive and 84% specific. If this test is used on a sample of patients with obesity in which 35% are known to have depression Based on the data, which of the following statements is most accurate concerning exposure to vinyl chloride in the cohort of 10,250 workers? A)Brain cancer, melanoma, and non-Hodgkin lymphoma mortality were significantly elevated among workers. B)Exposure to vinyl chloride significantly reduces the risk for Hodgkin disease among workers. C)Mortality from laryngeal cancer and lung cancer among workers is not statistically lower than expected. D)The expected number of deaths from liver cancer among workers was significantly higher than the observed number. E)The observed number of deaths among workers was significantly higher for cancers of the connective and soft tissues.

Question

Quizplus · Accepted Answer

Explanation: The standardized mortality ratio (SMR) quantifies mortality in a specific group as compared to the general population. It is the ratio of observed to expected number of deaths in a specific group of the general population under the assumption that mortality rates for the group are the same as those for the general population. The expected number of deaths is calculated based on age-specific mortality rates in a standard reference population (typically, the general US population). This value is then contrasted to the observed number of deaths in the specific group as follows: SMR = observed number of deaths / expected number of deaths The SMR is usually used in occupational studies to determine whether the observed number of deaths in a group (eg, workers) exposed to a specific risk factor (eg, vinyl chloride) exceeds what would be expected in a similar population (eg, US population) excluding the risk factor of interest. SMR <1 indicates that the number of observed deaths in the study group is lower than what is expected SMR = 1 indicates that the number of observed deaths in the study group is equal to what is expected SMR >1 indicates that the number of observed deaths in the study group is greater than what is expected A confidence interval (CI) that does not include the null value (1.0 for SMRs) indicates a statistically significant difference between the observed and expected number of deaths. In this case, the observed number of deaths due to cancers of the connective and soft tissues among workers was higher than expected, given SMR = 2.43 with a 95% CI (1.48, 3.75). The 95% CI does not include the null value, indicating that the observed number of deaths due to this specific cause among vinyl workers is significantly higher than the expected number of deaths. (Choices A and B) Mortality due to brain and central nervous system cancer (SMR = 1.27 with 95% CI [0.95, 1.66]), melanoma (SMR = 1.09 with 95% CI [0.73, 1.56]), and non-Hodgkin lymphoma (SMR = 1.02 with 95% CI [0.79, 1.30]) was elevated among vinyl workers; similarly, exposure to vinyl chloride was associated with a reduction in risk for Hodgkin disease among workers (SMR = 0.37 with 95% CI [0.08, 1.08]). However, none of these results were statistically significant because all CIs included the null value. (Choice C) Mortality from laryngeal cancer and lung cancer among workers is statistically lower than expected (SMR = 0.56 with 95% CI [0.29, 0.97]; SMR = 0.88 with 95% CI [0.81, 0.95], respectively). The CIs exclude the null value. (Choice D) Given SMR = 3.68 with a 95% CI (3.04, 4.41), the observed number of deaths from liver cancer among workers was significantly higher than the expected number of deaths, not vice versa. Educational objective: The standardized mortality ratio (SMR) represents an adjusted measure of overall mortality. An SMR >1 indicates that the observed number of deaths in the population of interest (eg, vinyl chloride workers) is greater than the expected number of deaths in the standard reference population. The statistical significance of the SMR is established by the confidence interval.

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