Hypertension: rule of halves: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Hypertension: rule of halves

Sample item

In a community with 1000 hypertensive adults, the rule of halves holds exactly. How many of them are aware of the diagnosis, on treatment and adequately controlled, in that order?

A500 aware, 500 treated, 250 controlledB500 aware, 250 treated, 125 controlledC250 aware, 125 treated, 62 controlledD500 aware, 250 treated, 250 controlled

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. 500 aware, 250 treated, 125 controlled

The rule of halves says that half of hypertensives are unaware, half of those aware are not treated, and half of those treated are not controlled. From 1000 the figures become 500 aware, 250 on treatment and 125 controlled. Only about one in eight hypertensives is therefore controlled, which is the burden of the iceberg.

Option by option

A. 500 aware, 500 treated, 250 controlled
This halves only once, leaving all aware persons on treatment, which skips a step.
B. 500 aware, 250 treated, 125 controlled (correct)
Correct. Halving at each step gives 500, 250 and 125.
C. 250 aware, 125 treated, 62 controlled
This applies one halving too many at the start: half, not a quarter, of hypertensives are aware.
D. 500 aware, 250 treated, 250 controlled
This fails to halve the controlled step, and 250 treated would all be controlled.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, 500 aware, 250 treated, 125 controlled. The rule of halves says that half of hypertensives are unaware, half of those aware are not treated, and half of those treated are not controlled.

Why is "500 aware, 500 treated, 250 controlled" not the answer?

This halves only once, leaving all aware persons on treatment, which skips a step.

Why is "250 aware, 125 treated, 62 controlled" not the answer?

This applies one halving too many at the start: half, not a quarter, of hypertensives are aware.

Why is "500 aware, 250 treated, 250 controlled" not the answer?

This fails to halve the controlled step, and 250 treated would all be controlled.

What concept does this question test?

It tests Hypertension: rule of halves in PSM. From 1000 the figures become 500 aware, 250 on treatment and 125 controlled. Only about one in eight hypertensives is therefore controlled, which is the burden of the iceberg.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Hypertension: rule of halves?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.