Observational cohort study to monitor the use and safety of carvedilol in the treatment of heart failure in clinical practice in England – 1st interim report

Abstract

This is an interim report of a prospective observational cohort study to monitor the safety and tolerability of carvedilol in clinical practice when prescribed for heart failure in England. The utilization of carvedilol, management of adverse events in the community and the symptomatic progression of heart failure were examined. It is a non-interventional, observational cohort surveillance study using questionnaires sent to the patients' general practitioners. The general practitioners (GPs) of the patients identified by the Prescription Pricing Authority were sent an eligibility questionnaire if the patient had been newly prescribed carvedilol between September 1999 and July 2001. Further questionnaires requesting baseline clinical information about eligible patients (carvedilol indicated for cardiac failure) and subsequent event data were sent to consenting GPs at 12 months. The questionnaires also requested specific information about initiation and supervision of treatment, including severity of heart failure and treatment withdrawal. The data were analyzed by using descriptive statistics. In addition, the incidence densities (ID) of each event (per 1000 person-months of treatment) were calculated, ranked and the difference between the ID of each event in the first (ID1) and subsequent 5 months of exposure (ID2) was tested by constructing 99% confidence intervals (CI). Selected events of clinical interest would be followed-up for further information to enable causal association with carvedilol to be assessed. In this interim report we have data on a cohort of 847 eligible patients for whom we have received information from the first follow-up questionnaire. The treatment of carvedilol was initiated in a majority of cases by hospital specialists (87%, n = 735), however, for most of them, further supervision of treatment was done under shared care between GPs and hospitals (70%, n = 595). More than 90% of the patients were started on carvedilol in the recommended dose range for the management of cardiac failure. Amongst the patients where NYHA grade of cardiac failure was expressed, the majority of patients treated with carvedilol had NYHA II (37%, n = 281) and III (40%, n = 297) symptoms at the start of carvedilol treatment. On treatment with carvedilol, improvement in NYHA status was reported for 43% (n = 364) of this cohort, whilst less than 2.5% (n = 20) of the patients deteriorated. The events reported with the highest ID1 were malaise/lassitude (14.6), dizziness (12.2), cardiac failure (9.7), dyspnea (9.7) and hypotension (8.5). The most common events reported as reasons for stopping carvedilol were "drug not effective", "dyspnea", "dizziness" and "lassitude". No events were identified as new signals (according to the ID1-ID2 statistic) of adverse events associated with carvedilol. There have been no events identified in this cohort that have required specific follow-up at the time of writing this paper. In summary, the interim results show that there is effective cooperation between hospital specialists and GPs in the use of carvedilol in the management of patients with heart failure. It also shows that carvedilol was well-tolerated and that patients with mild and moderate heart failure benefit symptomatically when treated with carvedilol in routine clinical practice.