Non adherence with therapy is common in heart failure and can be detected in routine practice by serum ACE activity

Chronic heart failure (CHF) patients are elderly and on many drugs, which makes non adherence very likely. However, non adherence is notoriously difficult to assess. The use of ACE inhibitors in CHF gives a unique opportunity, which is to assess adherence with therapy in the routine situation by measuring serum ACE activity. We have now validated this as a useful procedure in routine clinical practice. We measured serum ACE activity in 73 CHF patients who were routinely attending outpatients. We related these values on an individual basis with whether that patient had actually redeemed enough prescription for ACEIs at community pharmacies to cover the expected time period. From the community pharmacy data, we found that 27% of CHF patients had <80% adherence with their ACEI therapy. We also found that a routine serum ACE activity value >12 u/l gave 91% certainty that that patient was <100% adherent with their ACEI therapy. At the other extreme, a serum ACE <6.5 u/l gave 81% certainty that the patient was >85% adherent with therapy. In conclusion, non adherence with therapy is common in CHF patients but it can be detected routinely, easily and cheaply by measuring serum ACE activity at the outpatient clinic.