Improving patient self-reporting of antihypertensive adverse drug events in primary care: a stepped wedge cluster randomised trial

About 25% of patients experience adverse drug events (ADEs) in primary care [1‐3] and over a quarter of these could be prevent if situations at risk were detected earlier [4]. Event severity could also be reduced if patients were better engaged in self-reporting to their general practitioner (GP) [4].

Antihypertensive drugs are amongst the main classes of drugs responsible for ADEs in primary care. Between 11 and 14% of antihypertensive treated patients experience at least an ADE [1, 2, 4]. Of note, different classes of antihypertensive drugs are often prescribed together or in combination with other drugs, increasing the risk of ADEs [5, 6].

It has been shown that ADEs reported by patients are complementary to those reported by professionals [7, 8]. However, patients report ADEs four times less frequently than healthcare professionals [8]. Collecting ADEs from a patient’s perspective is critical in reducing their occurrence, which could result in warranted and unwarranted healthcare utilisation, and ultimately rendering care more patient centred [7]. Hence, it seems important to encourage patients to report ADEs to their GP, particularly patients treated with antihypertensive drugs who are at high risk of ADEs.

It has been shown that information booklets can improve illness and drug management, reduce the number of medical encounters, and improve patient knowledge and drug adherence [9‐15]. In these previous studies however, patients were not encouraged to actively contribute to ADE reporting. A patient-centred booklet was therefore developed to improve communication and interaction between the patient and his GP on antihypertensive drug management [16]. The present study aimed at assessing the impact of this booklet on patient self-reporting of ADEs to their GPs.

The present study aimed at assessing a booklet for patients on antihypertensive drug management in order to encourage antihypertensive-treated patients to report ADEs to their GPs. Results showed that, by improving patient information and communication with GP, more patients self-reported ADEs to their GPs. The identification of ADEs by both patients and/or GPs was also improved. Initiation and modification of the prescription were shown to be most at risks for ADEs and should receive special attention. The intervention also improved patient satisfaction on GP communication and information given on high blood pressure management.

This study has several strengths. It is a large-scale study including 60 GPs and more than 1000 patients in two large French regions where the tested intervention was simple, hence a priori transferable to other clinical situations and sustainable. The interest of the stepped wedge design was previously discussed [18]. Finally, this design allowed us to show that the effect of the intervention was maintained whatever the period of the year (no effect of seasonality).

The study also has several limitations. First, the primary endpoint was the ADE self-reporting by patients to their GP, which represents an opportunity for the GP to improve antihypertensive drug management. However, we do not directly assess the effect of the intervention on the patient’s health status (fewer complications, better adherence, better control of hypertension,...). Yet, patient safety studies often choose a primary endpoint related to a frequency of ADEs. Second, due to a cluster design with randomization of GPs (and not patients), differences in the characteristics of the included patients were observed. In particular, there were more patients in the intervention condition with at least one medical situation presenting a risk of ADE. Although adjusted analyses showed more patient self-reports in the intervention condition, it cannot be excluded that other factors than the booklet participated in this improvement. Third, even if several patients of various socio-demographic origins and one linguist have been involved in the process of booklet development (see Table 1; 16), the booklet might be not adapted to all levels of health literacy which is known to influence patient ability to identify and report ADEs [22, 23]. The level of health literacy might have influenced patients’ capacity to report ADEs in both groups. Fourth, no data was collected on how the way the GPs delivered the booklet. This would have required conducting audio and/or video recordings of the handover of the booklet. Only the distribution of the booklet to the patient was checked. Finally, the results might be affected by an unbalanced Hawthorne effect (a change in behavior as a motivational response to the attention received through the research) between the intervention and the control groups, even if data collection was identical in both groups. Such bias, if present, would limits the generalizability of the results from research to clinical practice [24]. Future research should combine quantitative and qualitative approaches to improve the understanding of how such phenomena influences the results.

In the intervention group, the rate of patients experiencing at least one ADE was consistent with rates previously reported in primary care for antihypertensive treated patients [1, 2, 4]. The present finding suggests that the frequency of ADEs in patients treated with antihypertensive drugs may be underestimated without patient self-reports. Indeed, in the course of the research study, over half of ADEs were reported only by patients and not by their GPs. This discrepancy may reflect signs or symptoms which are not, according to GPs, related to the drug [25]. However, each reported ADE was validated by a study committee, limiting the risk of error. It is also possible that GPs do not systematically interview patients concerning ADEs or that patients did not systematically inform their GP of their symptoms.

A positive effect of the intervention was also observed on satisfaction concerning the information given by the GP on antihypertensive management and on GP communication [26]. The booklet had no effect, however, on patient knowledge about cardiovascular and antihypertensive-associated risks, which remained low. Of note, patient level of knowledge may have limited their use of the booklet and thus limited its effect on patient participation in ADE reporting [27]. Furthermore, it is well established that specific physician and patient communication behaviours are associated with improved patient health status, recall, treatment adherence, and satisfaction [28]. Although patient–physician communication is considered as a mediator of health care quality and patient safety [28], and the extensive research in this field, there seems to be no consensus on the best practice to improve it. This simple patient-centred information booklet on antihypertensive drug management may be sufficient to improve physician-patient interaction in clinical encounters.

Patients are able to identify ADEs. Hence, improving patient self-report of ADEs is a first step in improving drug management. This is all the more true when patients can self-medicate themselves. The fear of inducing nocebo effects is not, in our opinion, a sufficient argument to justify not informing patients about ADEs. Moreover, GPs should systematically look for ADEs when initiating or modifying an anti-hypertensive treatment.

By improving patient information and communication with GP, a patient centred-information booklet on high blood pressure management can improve patient self-reporting of ADEs to their GPs. Initiation and modification of anti-hypertensive treatments were at higher risks for ADEs and should receive special attention. The booklet delivery also improved patient satisfaction on GP communication and high blood pressure management. Future research should assess if the use of a such patient centred-information tool can improve GP management of ADEs and patient’s health status [29, 30]. It could be measured through the rate of antihypertensive prescriptions of the GPs in accordance with the last clinical recommendations and the rate of high blood pressure-associated medical complications concerning the patients. Patients should be followed over a long period of time to explore the impact of the booklet on patient morbidity-mortality.