Congenital connective tissue disorders known to be at risk for cardiac abnormalities such as mitral valve prolapse (MVP).

A screening study recruited 2000 individuals with congenital connective tissue disorders known to be at risk for cardiac abnormalities such as mitral valve prolapse (MVP). The screening involved two steps.  First the participants were examined by a general practitioner (GP) who recorded presence of audible heart murmurs. Those who were labeled as positive by GP were sent for a cardiology evaluation. After the evaluation by a cardiologist all participants underwent a final definitive (gold standard) echocardiography testing. The prevalence of echocardiogram-confirmed heart defects among individuals with congenital connective tissue disorders is 20%.  The sensitivity of a GP examination is 75% and the specificity is also 75%.  Both the sensitivity and the specificity of an evaluation by a cardiologist are 90%.

6.  What is the combined specificity and sensitivity of the GP examination followed by a cardiology evaluation in this study?

300 400 700

100 1200 1300

400 1600 2000

Sensitivity = 75%

Specificity = 75%

270 40 310

30 360 390

300 400 700

Sensitivity = 90%

Specificity = 90%

270 40 310

130 1560 1690

400 1600 2000

Sensitivity = 270/400 = 68%

Specificity = 1560/1600 = 98%

7.  Would you recommend implementing a screening program for cardiac abnormalities among individuals with connective tissue disorders? If so, would you use GPs alone, cardiologists alone, or a combination of a GP and a cardiologist? If not, why not?

Screening programs differ in their goals, so the answer depends on that. If a screening program aims to reduce the proportion of false negative tests for a potentially deadly disease, then high sensitivity is required. Specificity becomes more important if the goal is to avoid unnecessary invasive or expensive testing. A GP screening might not be sufficient in this case because the sensitivity and specificity are not high enough, and a cardiology exam may be too expensive.