The present study shows that HCPs considered themselves to actively support their patients in adhering to treatment with OACA by using a wide range of activities. The 47 listed care activities were all, to a greater or lesser extent, performed in clinical practice in the Netherlands and Belgium. However, in certain areas activities were carried out only to a limited extent.

The domain Knowledge consists of care activities that are mainly performed at the start of treatment. Providing information is required since patients need to understand the usefulness of a particular drug in order to consent to treatment. Patient education is often used in interventions to enhance medication adherence [22, 23]. However, to achieve awareness of the importance of adhering to OACA treatment the impact of non-adherence should be made clear. Most HCPs reported to discuss both the importance of adherence and the consequences of non-adherence. This is in line with their scores on the PAMQs where the majority of HCPs stated to have adequate knowledge about the consequences of non-adherence [14]. Care to maintain awareness, as reflected by the item ‘ask if a dose is missed’, is provided less frequently, particularly in Belgium. A study on nursing practices for patients on OACA treatment in Japan also found that nurses were less likely to ask patients with refills adherence-related questions [24]. Only a minority of HCPs performed usual care activities within the domain Self-efficacy. It is known that self-efficacy is an important factor influencing medication adherence and adequate self-management. It is addressed in theoretical behavioural frameworks [25] as well as in medication adherence oncology research [26, 27]. To raise self-efficacy (expected) barriers to optimal adherence must be identified and strategies to overcome these obstacles should be discussed. This requires HCPs to directly focus on medication adherence. Clear instructions are needed to finish the Intention Formation. Instructing patients about the regular intake is reported by almost all HCPs, but information to handle specific situations, for example what to do in case of a missed dose or in case of vomiting shortly after ingestion, is provided less frequently. This item clearly needs more attention. Activities classified in the domain Implementation also received relatively poor attention. Care activities within this domain focus on cues that are relevant to prevent unintentional non-adherence. Since adherence decreases by treatment duration [10, 28], care activities aimed at the continuation of a correct use are particularly relevant in long term treatment. In view of the current progress in selecting patients that will respond on OACA treatment, the number of patients on long-term OACA treatment is likely to increase considerably. Thus, there is a growing necessity to support on-going optimal use of OACA. Patients with support from their social environment are generally more adherent than those with insufficient support [29, 30]. Any opportunity to strengthen social support should not be missed. Adverse events generally have the full attention of HCPs. Most physicians, nurse practitioners and nurses performed all care activities within this domain. This finding is not surprising, as in oncology (serious) adverse events frequently occur. Adverse events may substantially impinge on the quality of life [29] and are related to non-adherence and early discontinuation of OACA use [10, 27, 30]. All physicians reported to inquire after experienced adverse events and their severity. In the case of more severe adverse events physicians must adjust OACA dosing regimens in an individual manner. For some OACA this can be accomplished without compromising efficacy [31, 32]. Obtaining information on the occurrence of adverse events and how they were experienced, as well as attempts to alleviate their symptoms are therefore common activities in oncology care. It is well known that unpleasant experiences regarding adverse events are associated with a lower level of medication adherence and higher levels of treatment discontinuation [4, 10]. The last domain, Facilitation, includes a variety of care activities. With respect to certain items there are striking differences between Belgian and Dutch HCPs. All Dutch pharmacists reported to ensure the timely transfer of medication information to other HCPs, whereas this is usual care for only a quarter of their Belgian colleagues. This suggests that there is a difference in the national organisation of information exchange between HCPs. It is interesting to note that in both countries the majority of HCPs usually does not intensify follow-up visits in the case that patients have problems with medication adherence.

Not all care activities can be and should be provided to all patients. Care should be tailored to the each patients’ situation and needs. On the other hand, all care domains appear to be relevant in maintaining medication adherence. We therefore recommend to cover all domains. Our list with care activities classified in domains can be used as a starting point to reflect on the level of care in one’s own clinical practice. Furthermore, in intervention studies researchers should be aware of the need to accurately describe both the standard or usual care. In clinical trials too often the control arm has been poorly defined [33, 34], resulting in uncertainty about the effects of the intervention studied [15, 33]. The differences in usual care activities between both studied countries reinforce this need.

The care provided usually to support medication adherence reported in this study differed among professions and country. Whereas in Belgium physicians performed more care activities to support adherence to OACA treatment, in the Netherlands a higher percentage of nurses and pharmacists reported to perform these activities. In line with their specialization, training in education, focus on self-management support and time spent on patient-contact, both in Belgium and in the Netherlands nurse practitioners performed the widest range of care activities. The impact of nurse practitioners on the quality of care in oncology has been shown previously [34, 35]. On the other hand, there was a large difference in care provided by pharmacists in both countries, with Dutch pharmacists performing considerably more activities than their Belgian colleagues. An explanation might be that in Belgium OACA are dispensed by hospital pharmacists, whereas in the Netherlands OACA are dispensed by specialized pharmacies in the outpatient clinics which resemble community pharmacies and are staffed by pharmacists who are trained in patient contact. In addition, Dutch pharmacists generally have access to a patients’ list of (co-)medication due to integrated electronic data services. Nevertheless, in both countries pharmacists only play a limited role in supporting adherence to OACA as compared to other HCPs. Since they are medicine experts and are well experienced in supporting medication adherence in patients with chronic diseases, greater involvement of pharmacists in the multidisciplinary teams may improve adherence care in (haemato-)oncology [36].

Successful care with regard to medication adherence, should not be dependent on individual HCPs but supported by a proper organization of care. Recent studies in other countries on current practices to support patients treated with OACA have revealed considerable variation in the extent and quality of the care provided [24, 37, 38]. A large survey among nurses in the US showed that in about half of practices policies and procedures to support patients were lacking and that interdisciplinary communication was inadequate [37]. A study among Spanish oncology pharmacists also demonstrated that adherence practices for oral OACA treatment were only implemented in about half of hospitals [38]. A nurse-based survey in Japan indicated that adherence-related practices varied and were associated with nurse’s background, type of treatment and healthcare system-related factors [24]. In line with the results of the present study, medication adherence management in patients treated with OACA as part of the care that is usually provided clearly shows opportunities for improvement.

For all HCPs participating in the present study, there was a strong relationship between the perceptions of medication adherence management and the number of care activities performed. Although the majority of HCPs stated to have adequate knowledge of medication adherence management [14], the association suggests that promoting HCPs’ awareness and increasing their knowledge about adherence management will improve the usual care that is provided to support patients in adhering to OACA treatment.

There are strengths and limitations to discuss. The present study provides an extensive survey of care activities performed by a variety of HCPs including physicians, nurse practitioners, nurses and pharmacists aimed to support adherence to OACA treatment. The list of 47 items was literature based and completed with input from medical oncologists, haematologists, nurse practitioners, nurses, pharmacists and researchers experienced in performing care activities related to promoting adherence to OACA treatment from two countries. A limitation to address is that these care activities were reported for patients using OACA for all types of cancer. Patients using long-term medication need to be supported in a different manner than patients with shorter life expectancies. Another limitation is that the response rate could not be calculated. Information on the number of HCPs reached with the postings and the number of the reached HCPs involved in the care for patients using OACA was not available. However, the respondents were employed in no less than 87 hospitals in the Netherlands and Belgium. Another limitation is the potential selection bias as the result of the methods applied. The questionnaire might have been filled out mainly by HCPs with awareness of the importance of medication adherence and/or those actively involved in the management of medication adherence. Furthermore, answers may be overstated by the tendency to give socially desirable answers. It is therefore not unlikely that in daily practice the medication adherence care activities are less extensively performed than reported. Finally, it would also be interesting to study these care activities from the patients’ perspective.