Practice exercise (made-up values, not clinical guidance). A town has 6000 inhabitants. At the start of a year, 95 of them have a chronic disease. During the year, 16 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 town has 31 000 inhabitants. At the start of a year, 1234 of them have a chronic disease. During the year, 179 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). In a cohort, groups of people were followed for different lengths of time (see the table: number of people and years of follow-up for each). During follow-up, 27 new cases occurred. Find the incidence rate IR per 1000 person-years. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 760 patients received a new treatment and 340 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the relative risk RR of the event with treatment. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 41% in relative terms (RRR = 41%). In a patient group the risk without treatment (CER) is 10% 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). 10 000 people are screened with a test of sensitivity 94% and specificity 83%. The prevalence of the disease is 8%. How many people with the disease are missed by the test (false negatives, FN)?
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