Practice exercise (made-up values, not clinical guidance). A town has 18 500 inhabitants. At the start of a year, 197 of them have a chronic disease. During the year, 52 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 38 500 inhabitants. At the start of a year, 1490 of them have a chronic disease. During the year, 568 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 test has a sensitivity of 84% and a specificity of 90%. Find the negative likelihood ratio LR−. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 930 patients received a new treatment and 390 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the number needed to treat NNT to prevent one event. Round up to a whole number of patients.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 76% and specificity 86%. The prevalence of the disease is 27%. How many people with the disease are missed by the test (false negatives, FN)?
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 75% and specificity 77%. The prevalence of the disease is 29%. How many positive results n₊ are expected in total?
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