Questionnaire study and audit of use of angiotensin converting enzyme inhibitor and monitoring in general practice: the need for guidelines to prevent renal failure.

OBJECTIVES: To determine the current pattern of use of angiotensin converting enzyme inhibitor and monitoring of renal function in general practice and to audit all admissions to a regional renal unit for uraemia related to use of these drugs.
DESIGN: Postal questionnaire sent to 400 general practitioners; audit of clinical notes of all patients receiving these drugs in one large general practice; audit of all cases of uraemia (creatinine concentration >500 micromol/l) related to treatment presenting to hospital renal services over 12 months.
SETTING: General practices in the North Wales health authority and one in central Manchester. Regional renal unit in Salford. MAIN OUTCOME MEASURES: Proportion of general practitioners who regularly monitored renal function before and after initiation of angiotensin converting enzyme inhibitors. Indications for treatment and details of monitoring of renal function in patients receiving these drugs. Incidence of related uraemia and evidence of comorbid disease, other aetiological factors, delayed detection, and patient outcome.
RESULTS: 277 (69%) general practitioners replied; 235 (85%) checked renal function before but only 93 (34%) after the start of treatment, and 42 (15%) never checked renal function. Angiotensin converting enzyme inhibitors were prescribed for 162 patients from a total of 3625 aged >35 years (mean age 66.4 (SD 15.9) years). Monitoring of renal function occurred before treatment in 55 (45%) and after start of treatment in 35 (29%) of the 122 patients treated in general practice. Angiotensin converting enzyme inhibitors could be causally implicated in 9 (7%) of 135 admissions for uraemia (mean age 74.2 (7. 2) v 62.1 (2.1) years; P<0.01). 3 patients had renovascular disease and 6 had congestive cardiac failure with another intercurrent illness. Renal function had not been checked in any patient after the start of treatment; mean duration of illness before admission was 10.5 (3.2) days. Mean length of hospital stay was 20.9 (10.4) days; there were 8 survivors.
CONCLUSION: Cases of uraemia related to treatment with angiotensin converting enzyme inhibitors are still encountered and are often detected late because of lack of judicious monitoring of renal function in vulnerable, often elderly, patients, especially at times of intercurrent illness. Guidelines for appropriate monitoring of renal function may help to minimise the problem.