An evaluation of a new patient compliance index using plasma propranolol levels

Propranolol levels in plasma were studied in relation to dose prescribed in order to assess poor compliance with antihypertensive treatment. Fifty consecutive ambulatory patients (36-81 years) having hypertension, including 19 with azotemia, were investigated. Patient interviews using questionnaires and chart reviews were used to evaluate compliance. A composite Compliance Index was calculated for each patient. Individual oral doses of propranolol ranged from 20 to 160 mg. Subsequent plasma levels were determined by high performance liquid chromatography. Good correlation between last oral dose (mg) per body weight (kg) and log plasma propranolol levels were observed in patients whose compliance indices were above the mean for this sample (r = 0.74, p less than 0.01), when blood pressure control was satisfactory (r = 0.66) or excellent (r = 0.78), and when serum creatinines were greater than or equal to 1.4 (r = 0.76, p less than 0.001). Poor correlations between dose and propranolol levels suggest poor compliance with treatment.