What impact did this change in prevalence have on the diagnostic test statistics?

Sensitivity and Specificity: You'll notice the sensitivity and specificity did not change when the prevalence changed. This is because they are properties of the diagnostic tests themselves, and therefore do not change when applied to different populations.

Predictive values (both positive and negative) change depending upon the patient population under study. Notice that the PPV was substantially higher in the high risk surgical clinic population (i.e. a lump in this population is more likely to be cancerous). As the prevalence of disease increases, the PPV will also increase, while the NPV will decrease.  Conversely, as the prevalence of disease decreases, the PPV will also decrease while the NPV increases.