Control of hypertension is associated with long term health outcomes.1,2 Adherence to pharmacological and non pharmacological therapy is essential in order to achieve such control.3–5 Adherence can be defined as the extent to which a person's behavior corresponds with agreed recommendations from a health care provider.6 Problems with follow-up of therapeutic recommendations are common in almost all pathologies7 and highly impacts the effectiveness of the treatment.8 The main factors related to adherence are the complexity of the therapeutic regimen and the adaptability of the recommendations to the usual habits of the patient. Also, the patient's knowledge about the pathology, previous experience with the health-care system, adherence to other previous recommendations, the doctor-patient relationship, patient's perception of health, and the benefits of the proposed recommendations are factors associated with adherence.6,9,10

Several interventions are proposed to improve adherence. Critical reviews have highlighted significant methodological problems,11-16 but the overall conclusion is that no single intervention is, per se, better than any other. A further conclusion is that combined cognitive and behavioural strategies are the most effective ones, and the evidence indicates that these aspects need to be incorporated into the design of strategies to improve adherence in the treatment of hypertension.12,13 Haynes et al.13 suggested that the interventions used need to be easy to apply in the health-care practice, and maintained over extended periods of time.

In the case of the hypertension, a condition that can exist for years without clinical symptoms, the problem of non-adherence and how to cope with it has long been recognized, and different recommendations have been introduced.3,15 In Spain,17,18 the percentage non-adherence to hypertension treatments is around 50%, a level similar to that of other countries and/or pathologies. Hypertension is a risk-factor for cardiovascular disease and is detected, evaluated, and treated mostly in the primary health-care setting. In Spain, the long-term control and follow-up of the hypertensive patient on an established treatment program is usually carried-out by clinic nurses under the direction and close supervision of the attending physician.19 This is also the case for other chronic pathologies such as diabetes or chronic bronchitis, as well as giving advice about diets and healthy lifestyle habits.20

The hypertensive patient with a long disease history can benefit from interventions that focus on improving adherence to the drug treatment in the primary health care setting as well as non-pharmacologic measures to improve control of hypertension. Nurses take care of the long term follow up of hypertensive patients in the primary health care setting.

We assessed the impact of information provided to patients in a personalized way by the clinic nurse with the objective of improving the patient's knowledge of the disease and adherence to the medication prescribed as well as the incorporation of healthy lifestyle habits. Also, we assessed the potential impact on systolic and diastolic blood pressure and body mass index (BMI).

The sample population included 515 subjects in the IG and 481 in the CG. During the follow-up, 79 patients in the IG (15.3%) and 49 (10.2%) in the CG exited the study (Fig. 1). No significant differences were observed between those who completed the study and those who did not (data not shown).

Figure 1.

Trial flow chart.

(0.42MB).

At the initial outpatient visit, the groups were comparable except that the BMI was significantly higher in the IG than the CG (Table 1). The mean age was 63 years, most participants were female, and two thirds of the participants had no formal education. About half of the participants had poor control of their hypertension, and the BMI in both groups indicated considerable obesity. The mean time since diagnosis of hypertension was 10 years. According to the Batalla test, one of every three patients was aware of hypertension as a disease. The majority of the participants knew about the anti-hypertension medications they had been prescribed and remembered more than two recommendations for healthy lifestyle habits.

In relation to the self-declared compliance, there was a divergence of findings depending on the test employed; 4% of patients declared difficulties with compliance on the Haynes-Sackett test, whereas non-compliance was 25% with the Morisky-Green test, and 12% with pill counting.

Table 2 summarises the changes observed within each group, presenting the intra-group differences (first and second columns in Table 2) comparing the data at the beginning and end of the study for each group separately, and inter-group differences (third column in Table 2) between the IG and the CG after 12 months of follow-up, including the 95%confidence interval (CI) of the difference. In both groups, all the variables in the awareness category improved significantly. The magnitude of the increase in knowledge of hypertension was much greater in the IG, according to the Batalla test. Indirect measures of adherence did not show improvement following the intervention, with the exception of the Morisky-Green test. At the end of the study, there were no statistically significant differences between the IG and CG groups, except in the Haynes-Sackett measure of adherence.

The educational intervention carried out in this study was directed towards improving knowledge and adherence in individuals regularly attending an educational program during outpatient visits scheduled by the primary care nurse. The aim was to achieve better control of hypertension. The study population had a long history of hypertension and a high BMI. The strengths of the study were the larger than usual study sample13 and the 12-month intervention period, which was also longer than those reported in the literature. However, the outcomes of this study were negative. This could be partially explained by the study population characteristics and the intervention itself.

Regarding the study population, although adherence to prescribed medication and the non-pharmacological methods is a key element in the control of hypertension,3,4,25,26 the long-term evolution of the condition in our study population implied a high risk of non-adherence, since there is evidence that adherence decreases with time elapsed since diagnosis.9 Nevertheless, the level of non-compliance declared by the patients was much lower than that observed in other samples of hypertensive patients in Spain. A meta-analysis by Puigventós et al.17 of the studies carried out in Spain and using the Morisky-Green test for comparison indicated a percentage of self-declared non-compliers of 55%, whereas this was 25% in our study. This difference could be partially explained because our study sample included individuals who were regular attendees of the follow-up visits scheduled by the primary health-care team, and who had a long history of hypertension, and the questionnaire was administered at their own health-care centre. In fact, the prevalence of non-adherence in hypertension has been considered highly dependent on the study population.15

Baseline data indicated that a control of hypertension of 40% was lower than that observed in other studies conducted in Spain as part of the MONICA project,27 indicating that there was room for improvement. However, after the intervention, no improvement in the control of the hypertension was observed. Studies performed in Spain that impacted compliance and control of hypertension were those focusing on recently-diagnosed patients with high blood pressure and, as such, were more likely to be predisposed towards greater adherence. Our results are consistent with the small effects of interventions aimed at improving adherence, with HTA observed in two meta-analysis,28,29 a recent review15, or in chronic conditions in general.30 However, the results obtained in this study, especially the sub-optimal control of blood pressure and the elevated BMI, underline the need for specific interventions with special emphasis on diet and exercise, which are not easy to carry out effectively in practice.31

The intervention was planned within the context of standard clinical practice and the criteria suggested by Haynes et al.13 This study was carried out with the aim of ease of application in the primary care setting, >80% follow-up of patients, and with clinically relevant outcomes in a large sample population that was maintained over a relatively long period. Our intervention was directed towards inducing a higher level of knowledge and behavioural changes in the patient, mostly through an intervention delivered by a trained nurse on the primary care team,32 which has been shown to be feasible but ineffective in HTA patients with long term evolution of the condition.

Several limitations of this study should be considered. Firstly, contamination of the CG. The majority of the outcomes improved in both groups over the 12-month follow-up. The randomization to the intervention according to the Primary Health-care Centre decreases the possibility of contamination between the groups; also, cluster randomisation was taken into account in the analysis. However, the administration of the follow-up questionnaire at each clinic visit, the protocol of scheduled clinic visits in both groups, and the effect of participating in a clinical trial could explain the improvements observed in the CG.33 Secondly, the nurse-led intervention had the advantage of proximity to the patient, but also the long-term clinical relationship these patients had with their nurse provider could have made changing their behaviour, which had been present for several years, during the study period difficult. Thirdly, it is clear that measures of adherence are not consistent, and it is not clear which of the instruments currently available is the most appropriate.16,34,35

In conclusion, our study evaluated an intervention based on repeated information given to the HTA patient by the clinic nurse within a primary care setting with negative results regarding HTA adherence and control. Further studies are warranted to define and reinforce adherence, and to design more specific interventions directed towards improving adherence among long term HTA patients in the primary health care framework that are feasible and easy to apply in every day practice.

EAG and JMB planned the study, discussed the results and wrote the manuscript. EP and VPG analysed the data, discussed the results, and contributed to the writing of the manuscript. All authors reviewed and approved the final version of the manuscript. EAG and VPG had full access to the data used in this manuscript, and take the responsibility for the integrity of the data and accuracy of the data analysis.

None declared.