Audit of use of ACE inhibitors and monitoring in general practice

Editor—Kalra et al’s paper describing an audit of monitoring renal function in general practice suggests that practice is often less than optimal, although associated with some uncertainty.¹ Unfortunately, the authors do not give confidence intervals around their estimates of effect—which we provide here. The fact that only 34% (95% confidence interval 28% to 39%) of practitioners checked renal function after initiating angiotensin converting enzyme inhibitors and 15% (11% to 19%) never checked it is an important finding. We disagree, however, with the authors’ conclusion that producing guidelines on monitoring, on its own, will lead to an improvement in practice.

The authors state that renal monitoring has been neglected in recent guidelines and cite the North of England evidence based guidelines on the use of angiotensin converting enzyme inhibitors in primary care (to which we contributed) as an example of this.² They recommend that “renal function should be checked before and 7-10 days after treatment is started in all patients and thereafter regularly (for example, annually) only in those with risk factors.” Rather than neglect the issue of monitoring, the North of England Guidelines Group prioritised it. The Agency for Health Care Policy and Research also prioritised it in its guidelines on heart failure,³ on which this section of the North of England guidelines drew explicitly.

The North of England guidelines recommend that “before initiation of angiotensin converting enzyme inhibition ... [patients] should have their blood pressure, renal function, and serum potassium measured. These measurements should be repeated one week after initiation of treatment and again one week after each significant increase in dosage.”² The guidelines go on to suggest monitoring of serum creatinine concentration at least annually in all patients and describe specific criteria for patients who develop renal insufficiency. Thus they actually propose monitoring standards more stringent than those suggested by Kalra et al, although it is acknowledged that no basis for recommending one monitoring period over another could be found. The evidence base is limited, although a recent small trial suggests that complications are rare.⁴

Merely publishing guidelines on monitoring seems insufficient if even those citing the guidelines do not recall the recommendations. More active strategies, perhaps through computerised reminders built into prescribing systems, are required; on the basis of Kalra et al’s paper they should be developed with some urgency.