A 32-year-old woman with a body mass index of 51 kg/m2 presents to you seeking guidance on weight management, including the use of medication. You recently reviewed a systematic review of RCTs comparing orlistat to placebo for weight management, which included an asymmetrical funnel plot. What type of bias could this indicate?
An academic researcher is investigating the efficacy of a new treatment for elderly patients with osteoporosis. Prior to commencing her own study, she intends to conduct a meta-analysis to consolidate existing findings on the subject. As part of her meta-analysis, she must evaluate whether publication bias exists in the literature.
What is the most effective method for the researcher to detect this?
A new rapid diagnostic test is developed to diagnose Alzheimer’s disease. The test is based on measurement of certain biomarkers in the blood that are associated with the disease. The sensitivity and specificity of the test is 80% and 85%, respectively.
What is the likelihood ratio for a negative test result?
You are evaluating a study on the use of masks in public places to reduce viral upper respiratory tract infections among elderly individuals. The study found that the treatment group, who wore a mask, had fewer cases compared to the control group who did not wear a mask. The absolute risk in the control group was 0.5 whereas the absolute risk in the treatment group was 0.3.
What is the number needed to treat for elderly individuals in this study?
A research study examines the advantages of incorporating a new antiplatelet medication with aspirin after a heart attack in patients over the age of 60. The study yields the following outcomes:
Percentage of patients experiencing
another heart attack within 3 months
Aspirin 5%
Aspirin + new drug 3%
What is the number needed to treat to prevent one patient over the age of 60 from having another heart attack within 3 months?
You are reviewing a study that is comparing a new flu vaccine against a regular vaccine currently prescribed. The study aims to determine if the new vaccine reduces the number of people getting the flu over a year. The results show 100 people got the flu out of 500 people on the regular vaccine and 50 people got the flu out of 500 people on the new vaccine.
What is the relative risk reduction in this study?
A group of medical students want to investigate the impact of childhood drug use on the diagnosis of dementia in later life. They propose a case-control study design. The students will randomly select a sample of patients with dementia (the cases) and a sample of patients without dementia (the controls). After this, patients will be asked to report their experience of childhood drug use. The hospital’s ethical review board is concerned with the study design. They argue that this study is particularly susceptible to recall bias and should be revised.
What is the specific concern of the review board regarding the proposed study design?
Which one of the following statements best describes a type I statistical error?
A circumstance in which a subject in a research project alters their behavior due to the awareness of being monitored is referred to as what?
A 47-year-old man seeks your guidance on quitting smoking and mentions his interest in using electronic cigarettes as a cessation aid. You recall reading a study that compared electronic cigarettes to nicotine replacement therapy for smoking cessation. The study involved primary care patients who were randomly assigned to either the intervention or control group.
What type of bias could potentially threaten the validity of this study?