Treating hypertension: the drugs and the patients. Discussion
Our results agree with others in the literature in suggesting that clinical practice guidelines on pharmacologic treatment of hypertension are not being implemented consistently. In our patients, although diuretics were the most frequently prescribed class of medication, enalapril was the most commonly prescribed drug and ACE inhibitors ranked second. Many diabetics, however, were not prescribed ACE inhibitors. β-Blockers were preferred only for patients who had already had myocardial infarctions and not for most patients with coronary disease who had no other contraindications.
Strengths
Our study has two strengths: it is based on observations of actual prescribing practices rather than on reported practices, and it has documented thoroughly patients’ clinical conditions. To our knowledge, only two other studies have considered comorbidity as an explaining factor, and, in those studies, the authors did not identify any relationship between associated conditions and prescribing practices. They do not report clearly, however, which clinical factors were considered, which hampers comparison with our findings.
Limitations
This study has limitations. Only one clinical setting was studied and the number of patients was small. A retrospective approach to data collection has shortcomings. Were all hypertensive patients identified? How valid are medical records as a source of information on patient care? In 1994, researchers estimated that about 15% of hypertensive patients were not identified correctly by their doctors. Perhaps as many as 20% to 80% of patients who visit physicians do not have their blood pressure measured. The objective of our study, however, was not to estimate the prevalence of hypertension in our practice. There is no reason to suspect that underidentification of hypertension is associated with a systematic bias in estimating the prescribing choices of physicians. Underidentification could lead to underestimating the number of patients not treated, if this phenomenon is associated preferentially with mild hypertension. Some studies on the validity of medical records as sources of information allow us to be confident in the data obtained from the charts. In a classic study, Romm and Putnam observed that information in medical records corroborated transcripts of actual encounters at 92% for the chief complaint, 71% for description of current illness, and 73% for diagnosis. To further validate our observations, we excluded all charts for which data were either insufficient (three) or did not support a diagnosis of hypertension (11). We suggest that there is no systematic association between potentially missing information and the type of pharmacologic treatment prescribed. Finally, the fact that the study clinic is a teaching setting can be considered a limitation also. The physicians, however, appear to share the prescribing practices of most North American physicians. The proportion of patients receiving monotherapy in our study (about 50%) is comparable to that observed in larger cohorts.
Our patient population consisted mostly of elderly women. It is possible that we did not have a sufficient number of young and middle-aged men to reveal specific prescribing tendencies for them. In a Canadian study, Vanasse et al observed that diuretics and β-blockers tended to be prescribed more frequently to patients older than 60 years. Other studies did not report any association between age and sex of patients and prescribing practices. New research results can modify treatment guidelines; our observations and all previous results were reported before the Stone study, which suggested that long-acting nifedipine (eg, Adalat) might help reduce complications from cerebrovascular disease.
Clinical practice guidelines
There seems to be a problem with implementing clinical practice guidelines on the pharmacologic treatment of hypertension. The right drugs are not necessarily given to the right patients. Our results suggest, however, that some recommendations are being followed. The contraindications to β-blockers appear to be well known, as is their indication for patients who have had myocardial infarctions. Still, we should be concerned that p-blockers were not the preferred choice for patients with coronary disease and that ACE inhibitors, although prescribed for most patients, were not prescribed for most diabetics, for whom they are the first choice. It is unlikely that socioeconomic factors can be blamed because, in Quebec, at the time of the study, elderly people and those on social welfare, who constituted a large part of our cohort, did not pay for drugs.
Interestingly, the trend in favour of calcium channel blockers and ACE inhibitors is not as strong in Europe, Australia, or New Zealand. Aggressive marketing of these new classes of medication (relying strongly on the bad publicity about the side effects of the first β-blockers) and lack of marketing of P-blockers probably explain the trend. Still, recent studies of second-generation p-blockers do not support the bad press that these medications receive. The pharmaceutical industry appears to be more effective at disseminating its messages than guideline developers are.
Key points
Family physicians prescribed diuretics most frequently, followed by ACE inhibitors, and then β-blockers. Enalapril (eg, Vasotec) was the most commonly prescribed medication, although only one third of diabetics received it. β-Blockers appear to be underused.
We cannot generalize our findings, but they suggest that some guideline recommendations are implemented well. Part of the discrepancy between practice and clinical guidelines might be due to the guidelines’ complexity. Emphasizing all recommendations equally could have hampered communication of a clear message. Too many recommendations might be as bad as too few. A better understanding of the problem could help focus the messages on the most questionable prescribing behaviours. We need studies such as this one on a larger scale and in various settings if we are to plan effective continuing medical education to improve physicians’ prescribing practices for hypertension.
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