Measures of Disease Frequency — Incidence, Prevalence

A public health team in Delhi conducts a survey on January 1st, 2024, to estimate the burden of diabetes in a population of 50,000. They identify 2,500 individuals with diabetes (both newly diagnosed and previously known cases). Six months later, on July 1st, 2024, they conduct a follow-up and find 200 new cases of diabetes in the remaining disease-free population. Which investigation/measure would be most appropriate to assess the risk of developing diabetes in the disease-free population during this 6-month period?

An epidemiologist studying two respiratory diseases in a mining community finds that silicosis has a prevalence of 15% with an annual incidence of 0.5%, while acute bronchitis has a prevalence of 2% with an annual incidence of 8%. Which feature best explains why silicosis shows this prevalence-incidence pattern despite lower incidence?

An epidemiologist is evaluating a newly implemented screening program for hypertension in a factory with 10,000 workers. On the first screening day (baseline), 1,200 workers are found to have hypertension. Over the next 12 months, among the 8,800 workers who were initially hypertension-free, 440 develop hypertension. The epidemiologist wants to determine which investigation/measure would be most appropriate to quantify the *new occurrence* of hypertension in this initially disease-free cohort.

During a 2-year prospective cohort study in Mumbai, 10,000 initially disease-free adults aged 40–50 years were followed to assess the incidence of hypertension. At baseline (Year 0), none had hypertension. At the end of Year 1, 200 new cases of hypertension were identified. At the end of Year 2, an additional 150 new cases were identified (total 350 cases). The investigators want to calculate the cumulative incidence of hypertension over the 2-year period. What is the cumulative incidence, and what does this measure represent?

A public health epidemiologist is conducting a cross-sectional survey in a rural district of Maharashtra to estimate the burden of type 2 diabetes mellitus. The survey identifies 450 cases of diabetes among 5,000 randomly selected adults aged ≥30 years. The district has a total adult population of 200,000. What is the most appropriate next step to establish the disease burden and guide resource allocation for diabetes management programs?