Sentinel surveillance is best described as:

• A. Real-time county-level incidence
• B. Clinical trial enrollment monitoring
• C. Comprehensive nationwide counting
• D. Reports from selected sites to detect changes in care quality; lacks specificity for cause

Answer: (D)

Sentinel surveillance relies on a network of selected reporting sites to monitor trends in a disease or health event, rather than trying to capture every case across an entire population. This setup provides timely signals of changes because the data come from consistently reporting sites over time, making it useful for early warning and trend detection. Because the system samples from a subset of sites, it may not reflect all cases or pinpoint the exact cause of a change. That trade-off—speed and efficiency with limited representativeness—explains why it’s not about comprehensive nationwide counting or precise causation. The description of using reports from selected sites to detect changes, while not specifying the exact cause, best captures the essence of sentinel surveillance.