MRCGP AKT Category: Evidence Based Practice, Research And Sharing Knowledge

AKT-1981

A new screening tool for lower gastrointestinal malignancies has been developed known as the Faecal Immunochemical Test (FIT). The test is hoped to be an improvement on the previous stool tests as the FIT targets human haemoglobin.

The researchers would like to determine the specificity of the FIT test for colorectal cancer in a study involving 3000 participants aged 50 and above. All participants undergo a FIT and are subsequently evaluated with colonoscopy, which is considered the gold standard test.

Out of the 1200 participants who tested positive on the FIT, 800 were later confirmed to have colorectal cancer on colonoscopy.

On the other hand, out of the 1800 participants who tested negative on the FIT, 100 were later found to have colorectal cancer on colonoscopy.

What is the specificity of the FIT test for colorectal cancer in this study?

AKT-1982

As part of a clinical audit, a medical student is analysing the characteristics of patients attending a hypertension clinic. She calculates that the mean age of the patients is 56 years old, and that the variance of the data is 64. She wants to calculate the standard deviation of the data set.

What is the connection between standard deviation and variance?

AKT-1983

The standardised mortality ratio for a group of elderly patients with antisocial personality disorder is 120 (95% CI 90-130). How should this result be interpreted?

AKT-1968

A new screening test called FingerChol has been developed to diagnose hyperlipidaemia with a point-of-care finger-prick test. To evaluate the effectiveness of the test, 200 participants aged 50 and above are screened with the FingerChol test. These patients also undergo the gold-standard test (formal lipid profile blood test) for comparison.

The results obtained are shown in the table below:

Hyperlipidaemic Not hyperlipidaemic
Positive FingerChol test 60 40
Negative FingerChol test 20 80

What is the positive predictive value of the FingerChol test for this population?

AKT-1984

A researcher is tasked with evaluating the effectiveness of olanzapine versus haloperidol in reducing symptom severity of schizophrenia (as per the Positive and Negative Syndrome Scale) for each dollar spent. What would be the most suitable study approach?

AKT-1969

A contingency table is created for a new blood protein marker to screen for breast cancer in women aged between 40 and 60 years:

Breast cancer present Breast cancer absent
New test positive 25 30
New test negative 20 900

What is the positive predictive value of the new test?

AKT-1985

You have collected blood pressure data of patients given a new medication being tested as a treatment for hypertension. The data includes the patient’s initial blood pressure reading, followed by a second measurement taken 10 minutes after administering the medication.

Upon initial analysis, it was found that the differences between the two measurements do not conform to a normal distribution.

What statistical test would be the most suitable to determine if there is a significant difference between the blood pressure readings before and after the administration of the new medication?

AKT-1970

A randomised controlled trial is conducted comparing a new medication or placebo for treatment of hypertension in adults aged 60 years or older. Study authors do a calculation to establish how large a sample size is needed for their study.

What term best describes the type of calculation conducted?

AKT-1986

A disease is discovered to have a standard mortality ratio of 140 in a surveyed population. Is it accurate to say that the disease is more fatal in this age group?

AKT-1971

You are evaluating a recent research on the advantages of omega-3 fish oils in individuals with confirmed ischemic heart disease. What is the significance of the study’s power?