MSRA Data Interpretation Flashcards

A study reports a relative risk reduction of 30% for a new drug compared to placebo. The control event rate is 6%. What is the absolute risk reduction?

Answer: 1.8%

Absolute risk reduction = relative risk reduction × control event rate = 0.30 × 6% = 1.8%; the NNT would be 1/0.018 ≈ 56 patients.

A new screening test has sensitivity 95% and specificity 80%. In a population with 5% disease prevalence, a patient tests positive. What is the approximate positive predictive value?

Answer: ~20%

In low-prevalence populations, even a test with high sensitivity and specificity yields a low PPV (~20%) because false positives outnumber true positives.

A randomised controlled trial reports a p-value of 0.03 and a 95% confidence interval for the mean difference of 0.5 to 4.5 mmHg. What can be concluded?

Answer: The result is statistically significant but clinical significance requires assessment of the effect size

A p-value <0.05 and CI not crossing zero indicate statistical significance, but whether a 0.5–4.5 mmHg difference is clinically meaningful requires separate evaluation.

Urinalysis shows: protein 3+, blood 1+, and microscopy reveals red cell casts. Serum creatinine has doubled in 2 weeks. What does this suggest?

Answer: Nephritic syndrome with rapidly progressive glomerulonephritis

Red cell casts with haematuria, proteinuria, and rapidly rising creatinine is the hallmark of nephritic syndrome with rapidly progressive glomerulonephritis requiring urgent renal biopsy.

A CXR shows bilateral hilar lymphadenopathy, diffuse interstitial shadowing, and no pleural effusion. ACE level is elevated. What is the most likely diagnosis?

Answer: Sarcoidosis

Bilateral hilar lymphadenopathy with interstitial infiltrates and elevated ACE is the classic radiological and biochemical pattern of pulmonary sarcoidosis.

A 24-hour urine collection shows protein 5.8 g/day. Serum albumin is 22 g/L. Cholesterol is 8.2 mmol/L. What syndrome is present?

Answer: Nephrotic syndrome

The triad of heavy proteinuria (>3.5 g/day), hypoalbuminaemia, and hypercholesterolaemia defines nephrotic syndrome regardless of the underlying glomerulopathy.