How to read a forest plot

Researchers undertook a meta-analysis of the safety and efficacy of antibiotic treatment compared with appendicectomy for the primary treatment of uncomplicated acute appendicitis. Randomised controlled trials were included if they investigated adult patients presenting with uncomplicated acute appendicitis, diagnosed by haematological and radiological investigations. The primary outcome measure was the presence of complications, including wound infection, perforated appendicitis, or peritonitis. Four randomised controlled trials were identified.1 The results of the meta-analysis for complications were presented in a forest plot.⇓ Antibiotic treatment versus appendicectomy for uncomplicated acute appendicitis: forest plot for complications Which of the following statements, if any, are true? Statements a , c , d , and e are all true, whereas b is false. Four randomised controlled trials were identified that compared antibiotic treatment with appendicectomy for the treatment of uncomplicated acute appendicitis. The primary outcome in each trial was complications. For each trial a relative risk was derived that compared the risk of complications for antibiotic treatment relative to appendicectomy. Relative risk has been described in previous questions.2 3 Each sample relative risk was an estimate of the population parameter—that is, the relative risk that would be observed if antibiotic treatment was compared with appendicectomy for the entire population of all adults with uncomplicated acute appendicitis. The purpose of the meta-analysis was …