Chapter 3, Problem 99P

Mental Health

The ε4 allele of the gene encoding apolipoprotein E (APOE) is strongly associated with Alzheimer’s disease, but its value in making the diagnosis remains uncertain. A study was conducted among 2188 patients who were evaluated at autopsy for Alzheimer’s disease by previously established pathological criteria [16]. Patients were also evaluated clinically for the presence of Alzheimer’s disease. The data in Table 3.15 were presented.

Suppose the pathological diagnosis is considered the gold standard for Alzheimer’s disease.

To possibly improve on the diagnostic accuracy of the clinical diagnosis for Alzheimer’s disease, information on both the APOE genotype as well as the clinical diagnosis were considered. The data are presented in Table 3.16.

Suppose we consider the combination of both a clinical diagnosis for Alzheimer’s disease and the presence of ≥ 1 ε4 allele as a screening test for Alzheimer’s disease.

What is the sensitivity of this test?

Table 3.15 Relationship between clinical and pathological diagnoses of Alzheimer’s disease

Table 3.16 Influence of the APOE genotype in diagnosing Alzheimer’s disease (AD)