The planning stage used triangulation of qualitative data from 3 preliminary studies to identify users’ needs, barriers and facilitators, and behavioral determinants: analysis of posts from a UK online BC forum, and interviews with patients and community pharmacists.

Online patient forums are frequently accessed as valuable sources of health-related information, particularly for managing side effects, where patients can find supportive, experience-focused comments and advice [21]. The aim was to identify how patients with concerns about MBCs sought support for their medication, what actions they took, and what responses they received from health care professionals (HCPs). Searches were conducted in the “Hormone Therapy” section of the Breast Cancer Now forum (data accessed May 15, 2019-December 31, 2020) using the following keywords: “brand*,” “tamoxifen,” “letrozole,” “anastrozole,” “exemestane,” and specific drug brand names in use at the time. Searches covered the period from January 1, 2013, to December 31, 2020. A total of 290 women were identified, of whom 277 (95.5%) experienced new or worsening side effects after brand switches. A research assistant extracted data into a Microsoft Excel spreadsheet, including brands, year of posts, patients’ age, years of treatment, drug names, side effects, contacts with pharmacists, and interactions with other HCPs. Multiple posts by the same individual were combined into a single entry so that each individual had only 1 record.

A second study interviewed women with lived experience of MBCs recruited through the Breast Cancer Now charity. Participants were recruited through an invitation advertised on the charity’s research web page. Interested patients completed an online form and were contacted by email. Eligible participants were aged 18 years or older, had previously been prescribed HT, and had experience with MBCs. Nine women were included in the study and interviewed by a research assistant between July 9 and September 19, 2021. Interviews were conducted via Microsoft Teams and Zoom (Zoom Communications, Inc; n=7 interviews) or by telephone (n=2 interviews) and lasted 24-63 minutes. Participants lived in different parts of England and had a mean age of 57 years. A semistructured interview explored patients’ attitudes, needs, challenges, and preferences regarding HT brand changes and was informed by interpretative phenomenological analysis (IPA) [22].

Informed by the previous 2 studies, semistructured interviews with 7 community pharmacists located in London and the South East region were conducted by YE between March 16 and April 11, 2022. This exploratory analysis aimed to provide a more comprehensive understanding of the MBC phenomenon by triangulating our existing data with pharmacists’ perspectives on the topic. An interview guide consisting of open-ended questions explored pharmacists’ experiences with MBCs, management of consultations, the potential role of pharmacists, and the feasibility of a contract to deliver a pharmacy service for patients with BC. Saturation was sought when patterns across all 4 topics were identified. Participants were purposively selected. Eligible participants were registered pharmacists or pharmacy technicians with experience dispensing HT medication. Participants were recruited through visits to pharmacies in London and Oxford, where participant information sheets (PISs) containing a link to register interest were distributed, and through snowball sampling, whereby participants shared the PISs with contacts in the region. One pharmacist agreed to participate but did not respond to attempts to arrange the interview. No participants were known to the researchers before the interviews. Individual interviews were conducted face to face (n=3), by telephone (n=2), and via Microsoft Teams with audiovisual recording (n=2), and lasted 15-25 minutes. Participant characteristics are presented in Table S1 in Multimedia Appendix 2.

Content analysis [23] was used to analyze women’s posts in the online patient forum. First, the research assistant inductively coded the posts, and the coding was audited by YE. Second, the codes were categorized according to behavioral factors using the Theoretical Domains Framework [24].

All interviews were audio recorded, transcribed verbatim, and analyzed. A patient interview guide was developed using an IPA approach [22], primarily because MBCs related to HT had not previously been qualitatively explored, and an experiential approach was sought to generate preliminary in-depth data to inform future interventions based on a PBA [19]. Further details of the study are published elsewhere [11]. Pharmacists’ interviews were analyzed using thematic analysis [25], in which codes were derived inductively by an experienced research assistant and audited by YE (25% of transcripts). The identification of themes was mapped to the study aims and discussed and agreed on by the researchers.

Finally, data triangulation across the 3 data sources was undertaken to support cross-validation and enhance the credibility of the MBC phenomenon as experienced by pharmacists and patients [26]. Findings were organized into barriers and facilitators and mapped onto the Theoretical Domains Framework [24] to analyze behavioral determinants. The synthesis is presented with an assessment of agreements and disagreements across the 3 data sets. In addition, a detailed behavioral analysis was conducted to document how the qualitative studies undertaken during the planning stage informed the development of the symptom diary intervention. Although the rich idiographic approach of the IPA study is not fully retained in this paper, data triangulation allowed us to strengthen the validity of the selected empirical evidence used in the behavioral analysis.

Following the planning stage, our team embarked on an intervention development process guided by the PBA [19]. A description of the methods used at each step is summarized below, following the Guidance for the Reporting of Intervention Development (GUIDED) [27] checklist for reporting intervention development (Multimedia Appendix 3).

The intervention followed Bandura’s social cognitive theory [28], which addresses the interplay between self-regulatory (personal) and environmental (social) determinants of health behavior. Previous systematic reviews have identified self-efficacy in medication taking as a potential predictor and modifiable factor influencing adherence and persistence with HT drugs [29,30]. Self-efficacy is a core concept in Bandura’s social cognitive theory [31] and refers to an individual’s belief or confidence in their ability to perform a specific behavior to achieve a desired outcome. Higher self-efficacy for medication taking has been significantly associated with greater HT adherence [32]. Evidence also suggests that self-efficacy is an important determinant of intentional nonadherence related to 2 other distinct behavioral components: self-efficacy in managing side effects [29] and self-efficacy in communicating with HCPs [32-34]. The latter is particularly relevant because concerns regarding MBCs increase patient-HCP communication, mainly with pharmacists and general physicians (GPs), as shown in our analysis of the online forum data below.

Self-efficacy is a precursor to self-management. In Bandura’s theory, cognitive and emotional factors (participant modeling and cognitive processing), alongside environmental factors such as verbal persuasion (social support), interact to influence self-management behaviors. Self-management in chronic conditions refers to the ability to monitor the condition (eg, side effects) and to achieve the motivation and emotional responses necessary to maintain an acceptable QoL [35]. While self-monitoring strategies, such as a symptom diary, are instrumental in increasing patients’ awareness and improving symptom management, evidence indicates that addressing a single factor to improve adherence is ineffective because of the multifaceted nature of adherence dimensions [36]. A meta-analysis on HT adherence found that only interventions involving bidirectional communication (ie, eliciting information from and providing information to patients) improved adherence compared with controls [37]. Thus, environmental factors such as social support, in the form of feedback on behaviors, represent an important source of self-efficacy for successfully managing medication-taking behaviors.

In addition, self-management programs for patients with BC are often not co-designed with patients and HCPs, which may reduce their effectiveness. Relatedly, in the United Kingdom, nonadherence to HT among ethnically minoritized patient groups is 1.48 times higher than among White British patients [38]. Patients with cancer living in deprived areas are more likely to experience delays in starting treatment (33% higher compared with those living in the least deprived areas) or delays in seeking help because they feel they would not be taken seriously [39]. These findings highlight the need for inclusive co-design approaches, as reflected in our recruitment strategies.

Rapid scoping reviews are particularly relevant for intervention development studies because of their exploratory nature and broader scope in determining what evidence is available across heterogeneous sources [40]. For this study, the review question was: “What patient diary interventions are available to support self-monitoring behaviors in cancer survivors after active treatment?” Additional elements of interest included intervention components and data on patients’ experiences, usability, acceptability, adherence, and QoL outcomes. Studies were excluded if diaries were used solely to report symptom scales, episode frequencies (eg, pain or hot flashes), or activities performed, without promoting further user engagement (ie, not intended to facilitate patient self-management behaviors or feedback from HCPs).

Searches included systematic reviews and primary studies of any design in the following electronic databases: Cochrane Library, PubMed, CINAHL, and APA PsycINFO. Because of time constraints, searches were limited to August 1, 2004, to August 31, 2024. The search terms used for each database were adapted to derive the most meaningful results, using a combination of free-text terms, MeSH (Medical Subject Headings) terms, and subject headings. Additional key papers were identified through reference lists, targeted author searches, forward citation searching, and the authors’ expertise.

The scoping review protocol has been published [41], and the review was conducted by JC and YE. The findings were used to inform workshop discussions on the most appropriate information for patients to record about symptoms, approaches to enhance self-efficacy, and problem-solving strategies to support information exchange during medication consultations.

Coproduction methods [42] informed the workshops, with the aim of developing a symptom diary in partnership with patients with BC and pharmacists. Recruitment of patients with BC took place in London, and Breast Cancer Voices and South Asian Health Action circulated the call for contributors. Women with lived experience of MBCs and diverse sociodemographic characteristics (age, ethnicity, language, and socioeconomic status) were selected. Community pharmacy participants were recruited through Local Pharmaceutical Committee networks via RNDD North London (Community Pharmacy Research Champions) and included pharmacists, pharmacy technicians, and locums with experience dispensing HT medication. Interested individuals were asked to register via Microsoft Forms.

We planned for a workshop sample of 20 participants, equally divided between patients and pharmacists and organized into 2 mixed groups. Although there is no established guidance on workshop participant numbers [43], we considered that smaller mixed groups would better facilitate effective communication and engagement across different perspectives (patients and pharmacists). Workshop attendees included 12 patients with BC and 5 community pharmacists. A diverse group of patients with BC was purposively selected during recruitment and included participants of different ages (range 38-73 years; mean 56 years), ethnicities (8 White and 4 from minoritized ethnic groups), residential backgrounds from the most deprived areas (n=8) and least deprived areas (n=4), and 1 participant with a physical impairment. Community pharmacists’ roles included locum pharmacist (n=1), superintendent pharmacist (n=1), pharmacy managers (n=2), and pharmacist (n=1), with a range of work experience (1-35 years; mean 20.6 years), serving communities in the most deprived areas (n=3) and least deprived areas (n=2). Attendee characteristics are presented in Table S2 in Multimedia Appendix 2. A summary of findings from the rapid scoping review was circulated to participants in advance.

A face-to-face workshop was held at London Metropolitan University in October 2024 and lasted 4 hours, including lunch and coffee breaks. The meeting began with a presentation of the ENABLE study, an introduction to the National Institute for Health and Care Research key principles of coproduction [44], the role of patients and stakeholders as research contributors, and the planned activities. In all workshops, pharmacists and patients worked together in small groups with 1 facilitator (1 Breast Cancer Now nurse, or 1 patient representative, or members of the research team [DS, RE, or YE]) to encourage understanding of each other’s perspectives, experiences, and challenges. This shaped group discussions toward a more feasible and practice-focused approach to symptom diary implementation. A handbook guide was developed for each facilitator, including instructions on the aims, questions, probes, and group management. A voting system was used to complement discussions for some activities, such as a diary format and content. The session concluded with a whole-group discussion and feedback on the workshop. The workshop was audio-recorded. Additionally, 3 online workshops were held on October 25 and 30 and November 5, 2024, via Microsoft Teams with audiovisual recording, following the same structure described above. These workshops included screen sharing of presentations, tasks, and materials, with voting activities completed orally. Workshops lasted 1.5-2 hours.

Based on the data triangulation conducted during the planning stage, theory-informed evidence on HT adherence interventions, the rapid scoping review, and workshop discussions, we developed the intervention guiding principles and logic model, as well as the intervention planning table (Table 3). The latter involved a behavioral analysis that first identified the mechanisms of action (MoAs) and subsequently the behavior change techniques (BCTs), based on the best available evidence reported in the Theory and Technique Tool [45], a resource for the development of theory-based interventions.

The group included 5 patients with BC with experience of MBCs from different ethnic backgrounds (South Asian, n=1; Indian, n=1; and White British, n=3), as well as BN, the patient and public involvement and engagement (PPIE) lead who chaired the group. As in previous recruitment strategies, participant selection aimed to ensure a plurality of lived experiences and demographic characteristics (see Table S3 in Multimedia Appendix 2). The initial patient advisory group (PAG) meetings were scheduled to provide feedback on the intervention components without prior involvement with the research team, in order to maximize members’ perspectives on the intervention from a fresh viewpoint. The PAG members are based in England, and meetings take place online. Breast Cancer Now and South Asian Health Action supported recruitment. Members participate in a series of scheduled meetings throughout the study and receive payment for their time in line with National Institute for Health and Care Research recommendations. The PAG reviewed diary prototype 1 and provided suggestions for prototype 2.

A purposive sample of community pharmacists (n=6) and pharmacists representing professional bodies (n=5), including the Royal Pharmaceutical Society, Community Pharmacy England, and National Pharmacy Association, were interviewed (see Table S3 in Multimedia Appendix 2). The PBA recommends a flexible approach to sample size during intervention design (5-10 participants, depending on study scope) [46]. The aim was to gather feedback from target users and key stakeholders on their views and practice-based experiences of the intervention design, offering new insights to complement those of the PAG, whose members had been involved in the study from the outset. Community pharmacists were recruited using the same criteria and through the organizations described above, while representatives from professional bodies were recruited through snowball sampling via a contact provided by RE. No participants were known to the researchers before the interviews, and there were no dropouts. All participants received a PIS explaining the purpose of the study. The semistructured individual interviews used a topic guide to explore views on the intervention and insights into barriers and facilitators to implementation. A synopsis of the intervention was circulated in advance, and pharmacists provided suggestions for diary prototype 2. Interviews were conducted by YE via Microsoft Teams with audiovisual recording and lasted 17-46 minutes. Interviews took place between November 28 and December 19, 2024.

We first produced a prototype of the diary, drawing on findings from the planning stage, rapid scoping review, and codevelopment workshops, which informed its format and content. The intervention planning table, alongside the intervention guiding principles and logic model, provided a framework for designing and mapping diary sections and items relevant to patient monitoring according to their potential to effect behavior change (ie, self-efficacy). Two further prototypes (2 and 3) incorporated modifications following feedback from the PAG, pharmacists, and the research team.

Workshops, interviews, and meetings were recorded and transcribed verbatim by JC. Workshop materials were also collected for data analysis. Interviews with pharmacists followed a thematic analysis approach [25], including independent inductive coding by JC and YE. Data collection initially focused on capturing all participants’ preferences and suggestions, followed by consideration of disagreements and consensus based on the number of contributors supporting each view. Final decisions regarding diary design and proposed modifications were based on their likely impact on facilitating behavior change and their alignment with the study protocol (eg, suggestions to use a mobile diary were documented but were not planned within the scope of this study). Modifications were recorded in a table of changes.

The studies received ethical approval from the London Metropolitan University Research Ethics Committee (approval number SSSP-4050119/SSPR 022). Written informed consent was obtained from all interviewed participants. Pharmacists received a £20 (US $27) voucher as a token of appreciation for their time. For the patient forum posts, individual consent was not obtained because of the practical challenges associated with obtaining authorization from a large online community. Authorization was granted by Breast Cancer Now forum moderators, and, following recommendations from the London Metropolitan University Research Ethics Committee, posts were paraphrased to minimize the risk of traceability through online searches.

Ethical approval was obtained from the Health Research Authority NHS (National Health Service) West Midlands-South Birmingham Research Ethics Committee (approval number 24/WM/0137) and the London Metropolitan University Research Ethics Committee (approval number SSSP-2024-025).

All participants signed a consent form and received £75 (US $101) for their involvement, in line with National Institute for Health and Care Research recommendations, as well as a certificate of attendance. Pharmacists were also offered a fee for locum backfill.

All participants provided electronic consent before the interview and were offered a £30 (US $40) voucher as a token of appreciation for their time.

The findings provide insight into “health care team and system factors,” including HCP interactions, drug distribution systems, drug availability (shortages), HCP beliefs about generics and side effects, and responsiveness to patients’ concerns. Health care team and system factors represent one of the multifaceted domains that the World Health Organization associates with medication nonadherence in chronic conditions [47]. Other domains include social and economic factors affecting patients, disease-related factors (disease progression and risk), therapy-related factors (treatment burden), and patient-related factors (self-efficacy and beliefs about medication) [47]. Overall, research on patients’ behaviors and psychological needs has received more scholarly attention than system factors or environmental context and resources, despite their potential to influence patients’ capability and motivation to adhere to treatment.

All data sets provided evidence that some women are brand sensitive and that these experiences, alongside the search for a single or alternative brand(s), often led to fortuitous solutions depending on pharmacy stock availability, pharmacists’ efforts to procure a specific brand, or GP agreement to prescribe by manufacturer name. Community pharmacists interviewed appeared responsive to patients’ brand-seeking behaviors and attempted to secure medications within the constraints described above (see Table S2 in Multimedia Appendix 4). Most pharmacists (with one exception) believed that different brands could cause different side effects, and their explanations reflected both a biomedical model (different excipients and E numbers) and a belief in patients’ lived experiences. Although there is no scientific evidence explaining how HT brands may cause different side effects, the explanations proposed by pharmacists, particularly the possibility that excipients may affect bioavailability, were shared by patients, who often scrutinized nonactive ingredients in search of validation for their perceived differences. Patients and pharmacists viewed community pharmacies as the ideal setting for HT medication consultations. Both groups recognized the need for pharmacist training on HT drugs and patients’ medication concerns. Pharmacists also anticipated the need for clear guidelines to manage these conversations, similar to the New Medicines Service [48], to ensure consistent advice for patients. Both groups proposed the use of a patient diary to support greater awareness of side effects, drug attribution, and beliefs about medications.

Pharmacists described patients’ requests for specific brands as challenging (time-consuming and, at times, costly for the pharmacy) and difficult to manage within the constraints of National Health Service prescription services and the Drug Tariff [49]. Although patients considered cost savings to the NHS as the reason underlying generic switching, they often did not understand the NHS prescribing framework or the financial implications for pharmacies operating as businesses. Some patients in the online forum described the process as “Every prescription pick-up is an anxiety-inducing moment” [P32-PaF], particularly when they sought only 1 specific brand, whereas pharmacists viewed this behavior as frustrating and, at times, unnecessarily self-inflicted:

This was compounded by patients who claimed to follow their HCP’s advice to stick to 1 brand,

This highlights, first, that brand sensitivity is not uniquely triggered by patients and, second, a disconnect within the care team regarding how the medication supply framework operates. Patients reported that concerns about MBCs undermined their confidence in taking medication and could affect treatment continuation:

We aimed to capture women’s lived experiences in our behavioral analysis (see Table S3 in Multimedia Appendix 4), scrutinizing the identified barriers, negative emotions, lack of knowledge, limited confidence in managing symptoms, and feelings of being undermined (not listened to) during conversations with HCPs, who often questioned the validity of their experiences. The latter was carefully considered in our analysis of self-monitoring behaviors (diary use) proposed by women themselves, in a way that balanced their experiences with MBCs and those of pharmacists, for whom the need for specific communication skills and guidance in managing these conversations was acknowledged. Self-monitoring through digital technologies is widely used in the prevention and treatment of chronic conditions, but it has also been associated with “individual responsibility,” shifting the burden of care onto patients [50]. Overall, women made it clear that support after discharge from the hospital was needed and that HCPs should listen to their concerns and offer better options for managing medication-related issues [11]. The research team envisaged pharmacy training and guidance as requiring alignment between existing medication consultation skills and the specificities of HT treatment in BC survivors. Further details on the online forum analysis and the patient and pharmacist interviews are available in Tables S1-S3 in Multimedia Appendix 4.

Taken together, these studies suggest that many patient interactions with community pharmacists could be construed as missed opportunities to provide care and advice for symptom management beyond a narrow focus on brand-related discussions. As it stands, system factors (wholesaler stock, medication shortages, and GP prescribing by brand name) and scientific principles (generic bioequivalence) appear to place self-management and side effect control beyond patients’ capabilities and limit the support pharmacists can provide. In summary, the 3 intervention components identified during the planning stage were informed by the preferences of patients and pharmacists and included a self-monitoring diary, a pharmacist training package, and consultation guidelines. The next section reports findings from the diary development process.

A total of 29 reports (including 19 studies) published between 2007 and 2024 were identified, of which 8 were from the United Kingdom. Study designs included protocols (n=4); intervention design studies using mixed methods (n=3) and qualitative methods (n=3); feasibility studies (n=4); pilot studies (n=5); randomized controlled trials (n=3); postintervention studies using qualitative (n=1), quantitative (n=1), and mixed methods approaches (n=1); systematic reviews (n=2); an overview of reviews (n=1); and a Delphi study (n=1). Most were intervention studies (n=24) involving different cancer types (eg, uterine/cervical, breast, colon, and prostate and lung cancers, among others). Diaries were used to improve physical activity and healthy diet (n=18), QoL (n=2), symptom management (n=3), and medication adherence (n=2). Diary use required completion periods ranging from 3 days to 12 months, and the format was primarily digital (web- or app-based), paper only (n=3), or both paper and digital (n=1). Most articles used diaries to record activities, including the use of scales, whereas 2 studies used a diary more as a reflective tool [51,52]. Key diary components and outcomes were organized into potential barriers and facilitators (Table 1). Although evidence regarding the effectiveness of diary interventions remains limited (only 3 randomized controlled trials [52-54]), positive outcomes were reported across heterogeneous interventions (eg, increased physical activity, improved diet, or enhanced medication adherence) using behavioral targets relevant to supporting self-efficacy in our intervention (goal setting, problem solving, and social support). Evidence regarding factors that appeared to support or hinder engagement, usability, and acceptability of diary use among patients with cancer was also considered during workshop discussions.

Discussions were guided toward addressing key diary components based on patients’ and pharmacists’ needs and underlying behaviors identified during the planning stage, theoretical approaches related to self-efficacy in medication-taking behaviors, and findings from the scoping review identifying barriers and facilitators to diary engagement and relevant behavioral targets. The team outlined 2 broad sections for workshop discussions: (1) diary content and (2) preparation of key information for a medication consultation with a pharmacist. The discussion topics and aims are listed in Table 2.

Participants’ illustrative quotes and votes for the diary format are available in Tables S1 and S2 in Multimedia Appendix 5. At this stage, we drafted the intervention guiding principles and the logic model (see Tables S3 and S4 in Multimedia Appendix 5), which provided a framework to design and map diary sections and items for the intervention content.

The analysis reflects the barriers identified among patients with BC with concerns about MBCs, factors influencing diary engagement among patients with cancer (informed by existing evidence), and the diary components and content most likely to address these issues. The behavioral analysis identified the MoAs and BCTs most likely to be effective in facilitating behavior change, based on the best available evidence reported in the Theory and Technique Tool [45]. Table 3 presents the intervention planning table.

Barriers to the target behavior identified through qualitative research informed the behavioral analysis. Some barriers, such as “experience disbelief about symptoms,” were specifically derived from data collected during the planning stage (see Table S3 in Multimedia Appendix 4) and further expanded during the development stage through workshop discussions (see Table S1 in Multimedia Appendix 5). During the workshops, participants introduced a new perspective of the diary as a form of “evidence” that could support patients’ reports of experiencing different side effects:

There was agreement regarding the types of issues to record, except for “environmental factors/life circumstances,” for which concerns about privacy were raised by participants from minoritized ethnic groups (patients and pharmacists). This consideration was incorporated into the diary instructions as an optional component. Regarding the “key summary of the diary” prepared for the consultation (problem solving), 1 patient found documenting actions taken to control symptoms problematic because “it dilutes the fact that it's the brand that is causing this specific problem” [PA8]. These points will be important to examine in future research, as they suggest that the extent of diary completion may differ among patients who feel more certain that side effects are brand-related, which may or may not influence reflective processes before the consultation. Of particular importance were patients’ discussions about the need for pharmacist feedback to balance the burden of completing a diary, as expressed by 1 patient: “that means that you can use it [diary] to empower yourself beyond your own self patience” [PA5]. A pharmacist similarly stated, “It’ll help them [patient] and the caring team make better decisions, definitely” [CP-1]. Social support was also identified in the scoping review [66] and theoretical approaches [37]. Finally, issues related to the acceptability of and engagement with the diary were informed by findings from the scoping review and workshops, during which participants voted on the main diary features (see Table S2 in Multimedia Appendix 5).

Once the barriers to MBCs had been identified through the planning stage and workshops, they were mapped onto the MoAs, a range of behavioral theoretical constructs, including those within the Theoretical Domains Framework, that represent the processes through which specific BCTs influence behavior. The team agreed to select BCTs for which evidence of a link to a specific MoA was available in the Theory and Techniques Tool [45].

Prototype 1 of the symptom diary consisted of 5 sections: (1) an introduction explaining the purpose of the diary and presenting 2 scales (pain and mood) for later reference; (2) “My Symptom Diary,” containing 8 questions; (3) “Preparing Your Medication Consultation With the Community Pharmacist,” designed to summarize key points; (4) feedback on the experience of using the diary; and (5) an appendix listing side effects for each of the 4 HT drugs, categorized as common, occasional, or rare.

Details of subsequent changes to this prototype version are discussed below.

The PAG members were satisfied with the design and purpose of the diary because it allowed patients’ different experiences and perspectives on what mattered to them to be captured. They also praised the prompts encouraging consideration of environmental factors, including personal circumstances, as a valuable approach for eliciting a broad range of factors to consider.

Regarding the diary content, members proposed the inclusion of 2 additional items to record: the date on which the medication was changed and whether the symptom had resolved. This was considered important given the possibility that medications could change while using the diary and that symptoms could fluctuate or be successfully managed by women. Members also questioned the inclusion of “fatigue” within the mood scale, as they perceived it to be a physical sensation rather than a mood-related state. We agreed to remove fatigue from the scale because the primary purpose of the diary was to facilitate women’s reflection rather than serve as a tool for quantitative data collection. Another point raised by the PAG concerned the summary of key points before the medication consultation. Patients suggested replacing “intentions” with “expectations,” given that a patient’s goals may not necessarily be fulfilled by the pharmacist, whereas “expectations” would empower women to express what they felt they needed and hoped to receive. In addition, participants suggested signposting patients to charity support before the medication consultation. Finally, 1 PAG member reviewed the entire diary for lay comprehension and made additional suggestions, which were incorporated alongside those described above.

All pharmacists were supportive of the use of symptom diaries, and many were familiar with their use for other medicines. Community pharmacists praised the diary for facilitating pharmacists’ support and increasing patient awareness.

No specific comments were made regarding the diary’s set questions other than its general design: “I think make it really simple for patients” [CP2-2]. Some pharmacists interpreted the diary as giving pharmacists a more proactive role (ie, linking side effects to factors recorded for pattern observation in specific brands).

It was explained that the initial expectation was that pharmacists would not read the diary because of time constraints and privacy concerns, and that they would instead advise patients based on the patients’ presentation of key points from the diary (medication expectations valued by patients). Medicine shortages were mentioned as a challenging issue for HT drugs, echoing previous qualitative evidence. There were also comments regarding the optimal time for introducing the diary to patients (ie, at medication initiation or when concerns arise). The research team initially planned to test the intervention among those who had concerns with brands, but its suitability at medication initiation could be explored in future studies, given the reported need for information and self-management support [2,11,13,14]. Feedback was incorporated into a table of changes, with relevant quotes included for illustration (see Table S1 in Multimedia Appendix 6).

A final discussion took place among the research team, the PPIE lead, and a Breast Cancer Now nurse, who received a copy of prototype 2 in advance. The team revisited components of the diary and the underpinning behavioral techniques, such as self-monitoring (confidence in recording symptoms) and problem-solving (identifying key points ahead of consultations), which were reviewed alongside feedback from the PAG and pharmacists. Many of the pharmacists’ views informed the training package (e-learning resource reported separately), in which patient-centered and shared decision-making approaches became more central to the intervention’s aim of upskilling pharmacists. Current medicine shortages were discussed as a timely opportunity to introduce the intervention, given the additional challenges associated with requesting specific brands. Specific changes related to the diary layout to ensure ease of completion and flexibility in the allocated spaces, following data from workshop contributions. Additionally, the team agreed that pharmacists would be well placed to signpost patients to charity information alongside other recommendations included in the medication consultation guide. Further details and quotes are presented in Table S1 in Multimedia Appendix 6.

Prototype 3 of the symptom diary was designed as a paper copy and in a word-processor format (to support offline completion and adaptability to systems other than Microsoft Word). The diary will be delivered by community pharmacists after training with an e-learning resource and following a medication consultation guide. Eligible patients (identified by pharmacists) are those who have previously expressed or are currently expressing concerns about MBCs. The estimated duration for completing the diary during the testing period is a minimum of 1 month and a maximum of 3 months. Prototype 3 contains the sections outlined in Textbox 1.