Practice exercise (made-up values, not clinical guidance). A town has 26 500 inhabitants. At the start of a year, 797 of them have a chronic disease. During the year, 348 more people are newly diagnosed (assume nobody moves away or dies). Find the cumulative incidence CI over the year per 1000 people at risk. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A town has 43 500 inhabitants. At the start of a year, 1708 of them have a chronic disease. During the year, 400 more people are newly diagnosed (assume nobody moves away or dies). Find the point prevalence P at the start of the year per 1000 inhabitants. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A case-control study compares 250 patients with a disease (cases) and 310 people without it (controls). The table shows how many in each group were exposed to a risk factor. Find the odds ratio OR for the exposure. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A test has a sensitivity of 96% and a specificity of 75%. Find the positive likelihood ratio LR+. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 40% in relative terms (RRR = 40%). In a patient group the risk without treatment (CER) is 36% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 97% and a specificity of 82%. It is used in a population where the prevalence is 30%. Find the positive predictive value PPV as a percentage. Round to one decimal place.
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