The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

Letter to the Editor

Editor, -The article by Hill and Smith (Aust Prescr 2005;28:34-7) states that when the blood pressure, on at least three separate occasions, exceeds the threshold pressures which predict an increased cardiovascular risk, treatment is required. They quote systolic and diastolic figures for triggering treatment, but then state that the patient's predicted cardiovascular risk should determine the time for intervention.

When does cardiovascular risk become 'increased'? Over what acceptable level? How is the 'predicted cardiovascular risk' used to delay the time for active intervention when one of the measurements has crossed the red line?

Why is there no reference in the entire article to discussion with the patient of their acceptable risk levels? The New Zealand Cardiovascular Risk Calculator to which they refer us has numbers needed to treat ranging from <10 to >120. The result of treatment is prevention of one cardiovascular event in five years.

This would suggest that even in a high risk 'herd' of patients, drenching all of them delivers benefits to very few. When the 'herd' consists of autonomous fellow human beings, should they not be involved in the good shepherd's calculations?

Warwick Ruse
Gastroenterologist
Cannington, WA

Author's comment

Dr S. Hill and Professor A.J. Smith, authors of the article, comment:

Our article's focus was first-choice medicines for hypertension. We could not embark on this without a brief, but not a full, account of the assessment of absolute cardiovascular risk and its application to treatment decisions.

Blood pressure is continuously associated with cardiovascular risk and therefore there is no discrete point at which treatment is mandated. Blood pressure should not be viewed in isolation from accompanying risks such as age, gender, ethnicity, smoking, lipids, glucose, family history and body mass index - the ingredients currently used for calculating absolute cardiovascular risk.1

What is an 'acceptable' level of risk? The New Zealand guidelines, and our own National Heart Foundation, recommend lifestyle advice alone for individuals whose risk of a cardiovascular event over the next five years is less than 15%. Any threshold for treatment is a compromise between unnecessary intervention (the 'Number needed to treat (needlessly))'.2 culpable inactivity and economic feasibility. If, however, the approach of establishing absolute cardiovascular risk is taken it is impossibleto leave the patient out of the discussion. We agree that this is essential for any intervention and particularly one that will last a lifetime.

References

  1. The New Zealand Cardiovascular Risk Calculator. In:The assessment and management of cardiovascular risk. Best practice evidence-based guideline. Wellington, NZ: New Zealand Guidelines Group (NZGG); 2003. p. xxii. [cited 2005 Aug 22].
  2. Bogaty P, Brophy J. Numbers needed to treat (needlessly?). Lancet 2005;365:1307-8.