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QUESTION 1 OF 4

The following is the abstract from a recent paper: “the mean difference in pain relief between the intervention group and the control group as calculated using a 0-100mm VAS was 13.2mm (95% CI -8.1mm to 31.1mm)”.
Which of the following statements is true?

QUESTION ID: 1231

1. A 95% of the control group reported -8.1mm to 31.1mm pain relief.
2. A 95% of the intervention group reported -8.1 to 31.1mm pain relief.
3. A 99% CI would give us a more precise estimate.
4. A p-value would have been useful to calculate statistical significance.
5. The observed difference in pain relief between the intervention group and the control group was probably due to chance.

QUESTION 2 OF 4

Researchers found that a Gram stain had a sensitivity of 65% and a specificity of 40% for diagnosing septic arthritis of the knee.
Which of the following statements is true?

QUESTION ID: 1232

1. 40 out of 100 patients with septic arthritis of the knee would fail to test positive with gram stain.
2. 40% patients with a septic arthritis was identified with the gram stain.
3. 65% patients identified as having a septic arthritis had actual septic arthritis.
4. Gram stain was false positive in 35% cases.
5. Gram stain would not be a reliable test to rule out a septic arthritis

QUESTION 3 OF 4

The authors investigated the diagnostic accuracy of asymmetric skin creases for diagnosis of pathological Developmental dysplasia of the hip(DDH). They found that the positive predictive value (PPV) of asymmetric skin creases for a diagnosis of DDH was 20% and the negative predictive value 70%. The Negative likelihood ratio (NLR) of the test was 0.248.
Which of the following is true?

QUESTION ID: 1233

1. A ROC curve would allow us to graphically plot the sensitivity against the specificity of the diagnostic test to assess for optimal test threshold.
2. It is important to ascertain the study prevalence before deciding that the clinical sign is unreliable.
3. Patients who were incorrectly labelled as negative outnumbered those who were correctly labelled negative.
4. The reliability of asymmetric skin creases in the diagnosis of pathological DDH will not change if the study is repeated in a different setting.
5. The test was more useful to rule in the disease.

QUESTION 4 OF 4

Researchers undertook a case-control study to investigate the relationship between sex, age and graft size as predictors of re-tear within two years of ACL surgery. Logistic regression with age, sex and graft size showed graft size < 8 mm (adjusted OR = 2.95; 95% CI = 1.33–6.53; P = .008) and age < 25 (adjusted OR = 7.01; 95% CI = 2.40–20.53; P = .001) were significantly predictive of re-tear. 
Which of the following is true?

QUESTION ID: 1234

1. A calculation of risk ratio would not have been appropriate.
2. Age>25 is not associated with risk of ACL re-tear.
3. Graft size<8mm is not independently associated with ACL re-tear.
4. The explanatory variables were continuous.
5. The results were not adjusted for the sex of the graft recipient.