Letters

Comparing hypertension guidelines

EDITOR,--T P Fahey and T J Peters illustrate well the difficulties that general practitioners face in deciding whether to treat hypertension, given the variation in published guidelines.¹ One factor that they do not consider, however, is that the treatment levels set in guidelines are based on evidence from trials rather than measurement in normal practice.

We examined blood pressure readings in West Sussex. We expected to find lower systolic and diastolic blood pressures than the national average, given the recently confirmed evidence that blood pressures in areas of low cardiovascular mortality are lower than the national average.² Instead, where we could analyse individual readings we found that, although recorded systolic pressures in both sexes were lower (P<0.0001) than national values,³ recorded diastolic pressures in both sexes were higher (P<0.0001). Figure 1 shows the results by age group for women (n = 1316); the results for men (n = 846) showed a similar trend.

View larger version (127K): [in this window] [in a new window]   Fig 1--Mean blood pressure by age group in women in West Sussex (n = 1316) and in England (n = 1423)

Given that in general practice blood pressures are taken by a variety of team members, this consistency was remarkable. Interviews with team members confirmed the use of the phase IV Korotkoff sound as opposed to phase V, which is generally used in trials and national surveys.³ It is therefore likely that many people diagnosed as being hypertensive in practice would not be so diagnosed in a clinical trial and that published recommended levels for starting treatment are in practice artificially high.

Consistency is undoubtedly needed in guidelines, but guidelines also need to reflect the practice of medicine in vivo as opposed to the rarefied atmosphere of clinical trials and national surveys.

Senior registrar in public health medicine East Sussex, Brighton and Hove Health Authority, Brighton BN1 4ST

Medical statistician Institute of Public Health, University of Cambridge CB2 2SR

General practitioner Silverdale Road Surgery, Burgess Hill RH15 0EF

T J Scanlon, R Luben, P Lyle 

1. Fahey TP, Peters TJ. What constitutes controlled hypertension? Patient based comparisons of hypertension guidelines. BMJ 1996;313:93-6. (13 July.) [Abstract/Free Full Text]
2. Whincup PH, Cook DG, Adshead F, Taylor S, Papacosta O, Walker M, et al. Cardiovascular risk factors in British children from towns with widely differing adult cardiovascular mortality. BMJ 1996;313:79-84. [Abstract/Free Full Text]
3. Office of Population Censuses and Surveys, Social Survey Division. Health survey for England 1993. London: HMSO, 1995. (Series HS No 3.)