Practice exercise (made-up values, not clinical guidance). A town has 20 500 inhabitants. At the start of a year, 770 of them have a chronic disease. During the year, 359 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 new test was compared with the reference standard in a study (see the 2 × 2 table). Find the accuracy Acc as a percentage. 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 800 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 new test was compared with the reference standard in a study (see the 2 × 2 table). 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 18% in relative terms (RRR = 18%). In a patient group the risk without treatment (CER) is 29% 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 75% and specificity 93%. The prevalence of the disease is 23%. How many positive results n₊ are expected in total?
Full step-by-step solutions: practise this topic on examproblems.com.