Guidelines adherence and hypertension control in an outpatient cardiology clinic in Malaysia

Purpose: To evaluate doctors’ adherence to Malaysian Clinical Practice Guideline (CPG) 2008 in established hypertensive patients with cardiovascular diseases and factors associated with guideline adherence and hypertension control in Pulau Pinang Hospital, Malaysia. Methods: Prescriptions written by 13 doctors for 320 established hypertensive patients with cardiovascular diseases (25 patients per doctor) were noted on first visit. Two hundred and sixty (81%) of the enrolled 320 patients (20 patients per doctor) were followed up until the second visit. Blood pressure (BP) noted on the second visit was related to the prescription written on the first visit. Results: One hundred and ninety one (73.5%) patients received guidelines-compliant pharmacotherapy. CPG adherence had statistically significant association with left ventricular hypertrophy (LVH) (Ф =-0.241, p < 0.01) and diabetes (Ф =-0.228, p < 0.01). One hundred and fifty four (59.2 %) patients were on goal BP. Hypertension control had statistically significant association with guidelines compliance (Ф = 0.175, p < 0.01), angiotensin converting enzyme (ACE) inhibitors (Ф = 0.195, p < 0.01), diabetes (Ф = -0.148, p = 0.017), LVH (Ф = -0.153, p = 0.017) and monotherapy (Ф = 0.168, p < 0.01). Conclusion: Prescribing practices were fairly compliant with guidelines. Doctors poorly adhered to guidelines in hypertensive patients with diabetes and LVH. Significantly better hypertension control was seen in patients who were on ACE inhibitors and guidelines-adherent therapy.


INTRODUCTION
The goal of hypertension therapy and control is to reduce morbidity and mortality by preventing cardiovascular, cerebrovascular and renovascular diseases. Randomized control trials have shown that pharmacological intervention and adequate blood pressure control were associated with 20 to 22 % risk reduction of coronary heart disease [1] and 28 to 38 % risk reduction in the incidence of stroke [2]. To improve hypertension control, various hypertension management guidelines have been published, disseminated and regularly updated. These guidelines provide concise, evidence based recommendations to the prescribers in order to achieve optimal hypertension control [3].
Despite the positive impact of guidelines' implementation on hypertension control [4], existing literature suggests that patients with hypertension are not being treated according to guidelines [5]. Observational studies have shown that the health care providers' attitudes, behavior towards hypertension management and deviation from the clinical practice guidelines account for more than 66 % of the poor control of hypertension [6]. Just like other parts of the world, prevalence and poor control of hypertension is alarmingly high in Malaysia. In 2004, 40.5 % of Malaysians aged ≥ 30 years were suffering from hypertension, and only 28.6 % of the treated hypertensive patients were on goal BP [7]. It  On 1st visit, a purpose-developed validated data collection form was used to collect patients' demographic and clinical data. Hypertension diagnosis and other comorbidities were based on documentation from patients' medical record. Patients with history of angina pectoris, myocardial infarction or any diagnosis of coronary artery disease were considered to have coronary heart disease (CHD). Multiple comorbidities were noted and reported as different disease entities, for example, the number of patients with diabetes mellitus, kidney disease, stroke and others was reported individually. Implicit review of the patients' medical record was conducted to note adverse drug reactions, contraindications and statement about the inefficacy of a drug which may indicate why the drug is changed or not prescribed or other acceptable rationale for non-adherence to guidelines.
A total of 260 patients of the enrolled 325 patients (20 per enrolled doctor) were followed-up to the 2nd visit. On the second visit, BP readings were noted and patients were categorized either as having controlled or uncontrolled hypertension based on the goals defined by CPG 2008 (Table 1). Prescriptions written on the 1st visit classified either as adherent or non-adherent to CPG 2008 were then related to hypertension control status on the 2nd visit.

Data analysis
Data were analyzed by using Statistical Package for Social Sciences (version 16.0, SPSS Inc, Chicago, IL). Categorical data were reported as frequencies and percentages, and continuous data as mean ± SD. Chi-square and Fischers Exact tests were used to detect significance between categorical variables. P < 0.05 was considered statistically significant. When significant association was observed, the strength and direction of association was determined using Phi coefficient. Phi values from 0.000 to < 0.10, 0.10 to < 0.2, and 0.20 to < 0.40 were considered as negligible, weak and moderate association, respectively [9]. A negative Phi value indicates negative association between the variables [10].

Clinical practice guidelines adherence
One hundred and ninety one patients (73.5 %) received CPG (2008) compliant therapy. CPG adherence was found to have a statistically significant moderate negative association with LVH (Ф = -0.241, p < 0.01), and diabetes mellitus (Ф = -0.228, p < 0.01). No statistically significant association was found between CPG adherence and any other variable (Table 3).

DISCUSSION
In our study we found an overall fair level of adherence to medication recommendations of CPG (2008). More than two third (73.5 %) of the total prescriptions written were in compliance with CPG 2008. This finding is in contrast to some of the previous studies conducted elsewhere and Malaysia [11,12] which have reported poor adherence to guidelines, but is in compliance with some studies which have reported good adherence to guidelines [13,14]. This fair level of adherence to the hypertension guidelines might be due to the model proposed by Piette and Kerr [15]. According to the model, patients with concurrent comorbidities of overlapping pathophysiological pathways and management like hypertension and cardiovascular disease are more likely to receive guidelines adherent management. Similar guidelines recommended hypertension management was found to be significantly associated with patient total comorbidities, coronary artery disease, and history of myocardial infarction [16]. In the present study, CPG adherence was found to have negative association with diabetes mellitus and left ventricular hypertrophy. A similar report of doctors' poor compliance to hypertension guidelines while treating hypertension in diabetic patients was shown by another study conducted in Malaysia, where only 18.3 % of the diabetic hypertensive patients were on guidelines recommended ACE inhibitors [12]. In our study the possible reason for poor adherence to guidelines while treating diabetic hypertensive patients might be the fact that the clinic is a specialist clinic focusing on treating cardiovascular disease. However, a large-scale study in various cardiology clinics will be needed to confirm this. Another possible reason for poor adherence with hypertension guidelines in patients with left ventricular hypertrophy might be due to the fact that only a single antihypertensive class, Angiotensin receptor blocker, is recommended by CPG (2008) as first choice, compared to the wider range of antihypertensive classes recommended for coronary heart disease and heart failure. In the present study, 7 (53.8 %) patients with left ventricular hypertrophy were receiving diuretics as compared to 4 (33.3 %) patients who were receiving guideline recommended angiotensin receptor blockers.
In our study, majority of patients (59.2 %) were at goal BP on the 2nd visit, a rate that was more than twice that of the Malaysian national bench mark of hypertension control (26.8 %) [7]. Hypertension control in our study was much higher than a recent multicentre study conducted in Malaysia, in which 48.5 % of the patients had achieved BP control [17]. Reasons for this better hypertension control, compared to other studies conducted in Malaysia, might be the aggressive pharmacotherapy and doctors' greater compliance to hypertension guidelines. Similar better hypertension control in patients suffering from cardiovascular disease is reported by a study conducted elsewhere [18]. Better control of hypertension in patients suffering from cardiovascular disease might be due the fact that physicians seeing the patients with a critical disease pay more attention [19], and physicians and patients become more aware of the needs to maintain BP goal levels, once organ and vascular complications present [18].
Hypertension control had statistically significant positive association with CPG adherence and ACE inhibitors. Majority of the previous studies which have evaluated physicians' adherence to hypertension guidelines have not related practices to hypertension control. This finding was in compliance with the study conducted in Malaysia where adherence to recommended practices resulted in better hypertension control [4]. The efficacy of ACE inhibitors in patients at high and lower risk of cardiovascular disease like those with coronary heart disease, congestive heart failure, cerebrovascular disease, chronic kidney disease, and diabetes has been demonstrated by several large clinical trials [20,21]. Due to this reason ACE inhibitors are recommended by guidelines as choice of therapy in these conditions [3]. A majority of patients in our study were suffering from these conditions, so better control of hypertension in patients receiving ACEI was in compliance with guidelines recommenddations and findings of the above stated trials.
Hypertension control was found to have statistically significant negative association with diabetes, left ventricular hypertrophy, and patients on monotherapy. Similar poor hypertension control in diabetic patients was reported by a study conducted in Malaysia, where only 3.1% diabetic hypertensive patients achieved the target BP of less than 130/80 mm Hg [12] . One possible reason for the negative association could be the more stringent BP goals (hypertension with diabetes mellitus and/or CKD <130/80 mm Hg, and with proteinuria > 1 g/24 h < 125/75 mm Hg) which are difficult to achieve in clinical settings [22]. Besides, this statistically significant negative association between CPG adherence and diabetes might have adversely affected hypertension control in diabetic patients, because of significant positive association between CPG adherence and hypertension control in our study. The negative association found between hypertension control and LVH seems to be a consequence of noncompliance to hypertension guidelines. This finding further strengthens the concept that adherence to hypertension guidelines leads to better hypertension control. The poor control of hypertension in patients receiving monotherapy as compared to polytherapy seems logical, because most of the patients were suffering from multiple comorbidities and were in an age group in which BP control is normally achieved by using multiple antihypertensive drugs [3,23].

Limitations of this study
Conducting this study in a single site is the major limitation associated with our study. We evaluated prescribing practices only, and not the other components of hypertension management such as screening, life style interventions, pharmacotherapy and continued follow up. We followed patients for only one visit, hypertension is a chronic disease and needs a long observation period to decide whether the hypertension is controlled or not. However, to overcome this limitation we enrolled established hypertensive patients to make sure that BP reading noted on the 1st visit was the representative BP of the patient. The nonavailability of certain anthropometric measurements like body weight, Body Mass Index (BMI), etc, and statements about patients' compliance to pharmacotherapy are the potential limitations associated with our study.

CONCLUSION
Overall prescribing practices were in fair compliance with guidelines, but still have a room for further improvement Compliance to CPG 2008 resulted in better hypertension control in patients suffering from cardiovascular comorbidities. Poor adherence to guidelines in patients suffering from diabetes mellitus and LVH are the areas which need further probing and focus in the future. Different strategies like continuous medical education, seminars, reminder tools and the availability of clinical pharmacist to participate in collaborative practices and motivating patients to participate in BP goal achievement could increase guidelines adherence and hypertension control.