Practice exercise (made-up values, not clinical guidance). A town has 42 000 inhabitants. At the start of a year, 178 of them have a chronic disease. During the year, 395 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 positive predictive value PPV as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 920 patients received a new treatment and 980 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 case-control study compares 350 patients with a disease (cases) and 290 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 patient has a pre-test probability of 40% for a disease. A test with sensitivity 65% and specificity 98% comes back positive. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). Without a drug, 13% of patients have a certain side effect during a year. The drug raises this risk with a relative risk of RR = 2.17. Find the number needed to harm NNH: how many patients must take the drug for a year for one extra patient to have the side effect? Round up to a whole number of patients.
Full step-by-step solutions: practise this topic on examproblems.com.