We interviewed seven participants in Canada and eight in Spain. The mean age of participants was 32.5 years; most participants (9, 60%) had a university education, and nine (60%) were not currently pregnant but planning for a pregnancy at the time of referral for counseling. The majority were considered to be at high risk for VTE (12, 80%), and had previous experience with LMWH (12, 80%). We provide additional sociodemographic information, clinical characteristics, and participants’ previous experience with VTE and LMWH (Table 2).

Table 2 Sociodemographic and clinical characteristics of participantsQuantitative data – value elicitation exercises

For the rank ordering exercise, we used anchor states of ‘healthy pregnancy’ and ‘death’ as the best and worst potential outcomes. With regards to the intermediate outcomes being assessed, the majority of participants (87%) rated the health state ‘using daily injections of prophylactic LMWH during pregnancy’ as the best. This was followed by experiencing DVT (in 60% of participants). Experiencing a major obstetrical bleed and experiencing a pulmonary embolism were equally rated as the worst outcomes (40% participants). No statistical differences were observed between the rank ordering exercise and any of the sociodemographic and clinical characteristics (Supplementary Material 2, Table S1).

The VAS scores followed the same pattern: using daily injections of prophylactic LMWH during pregnancy (mean = 75.07 SD = 21.68) had the score closest to 100 (‘healthy pregnancy’), followed by DVT (mean = 40.40 SD = 26.57), and major obstetrical bleed (mean = 39 SD = 20.76) and pulmonary embolism (mean = 26.73 SD = 14.59) scores closest to 0 (‘death’). Statistical differences were observed between the VAS score for the health state of using daily injections during pregnancy and the pregnancy status; pregnant participants rated daily LMWH injections as being ‘closer to death’ than those planning pregnancy (57.17 vs 87). For the other sociodemographic and clinical characteristics, no statistical differences were observed (Supplementary Material 2, Table S1). Figure S1 (Supplementary Material 2) shows a histogram with the VAS scores for each participant.

Finally, in the standard gamble exercise, participants rated non-fatal health states as follows: daily injections of LMWH during pregnancy = 0.893, DVT = 0.871, major obstetrical bleed 0.833, and pulmonary embolism = 0.823. Of note, participants with university or high school degrees had a statistically significant higher standard gamble utility score for daily injections of LMWH during pregnancy (0.95) than those with college or some university degrees (0.77 and 0.71, respectively); similarly, participants in Spain had a significantly higher standard gamble utility score for pulmonary embolism (0.93) compared with those in Canada who reported a lower utility of (0.68). For the other sociodemographic and clinical characteristics no statistical differences were observed (Supplementary Material 2, Table S1). Figure S2 (Supplementary Material 2) shows a histogram with the SG scores for each participant.

Qualitative data – Burke’s pentad of motives

We identified 172 preferences in the interviews. Scene and agent preferences were the most frequent (26% each), followed by agency (22%), act (16%), and purpose (10%). There were no preferences tagged as unclear. In Table 3 we have presented representative quotes from participants (showing their risk of VTE and country) for each of the categories identified for Burke’s motives. No statistical differences were observed between the number of act, scene, agent, and purpose motives and any of the sociodemographic and clinical characteristics; however, for agency, statistical differences were observed between the number of agency preferences and the country (Spain 70% and Canada 30%) (Supplementary Material 2, Table S2).

Table 3 Representative quotes for each them of the motives scene, agent, act, agency and purposeAct

The act motive yielded 28 preferences and was reported by ten participants. Four primary actions for this step of the decision-making process were identified in this motive.

The first action was the most frequently reported and refers to the acquiring of more information from clinicians [P1] [P11]. Specifically, on: the effect of LMWH in those at lower vs higher risk of experiencing a VTE event [P12]; on drug administration and other effects of the drug [P9]; questions about practical issues like traveling while using LMWH [P13]; and on the best gestational age for administration of LMWH [P2] [P11].

The second action is the acceptance of their situation in which taking the medication is the expected action. Some participants assumed they were going to have to take it, while others were not aware that they could opt out of taking LMWH [P1][P3].

The third action was related to considering other treatment options (such as oral medications or expectant management). Participants indicated that their choice of options was influenced by the cause of their VTE. For instance, some had experienced VTE while taking contraceptive pills but had ceased using them by the time of the interview, which made them feel less vulnerable to that risk factor. Consequently, they sought less troublesome alternatives, including oral medications, regular check-ups with ultrasound of the lower extremities, or adopting healthier lifestyle behaviors [P12].

The fourth action was related to the burden of decision-making. Participants expressed frustration at the added responsibility of having to make yet another decision (regarding thromboprophylaxis) during pregnancy, alongside numerous other essential decisions [P6].

Scene

Scene preferences were the most prominent [43] and were reported by most of the participants [14]. This motive yielded five different contextual conditions.

The most predominant contextual condition reported by most participants, involved their previous personal experience of thrombosis and/or using heparin. The majority expressed a desire to take preventive LMWH during their next pregnancy, driven by the fear and anxiety surrounding their previous VTE [P8] [P14]. One participant showed some reluctance to use LMWH because of the daily needle pricks and the small absolute preventive benefits of the drug; however, due to their previous experience using LMWH and their ability to integrate it into their routine, that participant still expressed a desire to take injections rather than take no action [P15].

The second contextual condition is related to the sources of anxiety and fear about the potential clinical outcomes, leading them to prefer prophylaxis with LMWH. The majority expressed fear of experiencing a new VTE event, with pulmonary embolism being the worst health case [P14]. Two participants, however, were very concerned about how LMWH would affect their baby [P5]. Other sources of anxiety were the high level of uncertainty around the effects of the drug, not knowing the right moment to initiate LWMH, and that being pregnant already involves many other uncertainties [P1].

The third contextual condition was related to some participants’ personal disposition to risk aversion. All these participants preferred to avoid the anxiety caused by waiting and ‘not doing anything’ by proactively using LMWH [P1].

The fourth contextual condition was related to being pregnant or planning a pregnancy. Participants who were not currently pregnant at the time of decision-making (when the intervention was delivered), reported being uncertain about what decision to make, and expressed that they would probably have a different perspective (or will need to reassess their decision-making) once they are actually pregnant [P12].

The fifth contextual condition was related to participants’ access to health care. Some shed light on this by emphasizing their access to essential resources and the possibility of receiving routine health check-ups. The availability of these health care resources played a significant role in influencing their decisions [P12] [P6].

Agent

The motive of agent (i.e., a person or entity involved in the decision) was as prominent as scene (45 preferences) and was reported by all 15 participants. This motive contained three types of influencing people.

The category was related to the level of engagement participants desired when making decisions about their health. Eight participants preferred valuing clinicians’ expertise while wanting to search for information to better understand the risks and benefits of available alternatives. This dual approach reflects the participants' trust in their clinician's judgment while also taking ownership of their health choices by incorporating their own priorities[P10]. Six participants reported preferring a passive role, entrusting their clinician to make decisions regarding their treatment. However, all six emphasized their desire to remain informed about the best alternatives available and the reasons behind the recommended course of action [P14]. Only one participant reported preferring active involvement in the decision-making process, although she also listened to her clinicians’ recommendation [P11].

The second category was related to those that acted as decision-makers, i.e. who, other than the patient, were involved in the decision. Among participants, the majority reported that the decision was primarily made between them and their clinician. The majority of these participants felt supported by their clinician[P6] while fewer participants reported some degree of conflict with their clinician [P12]. Some participants also reported involving a family member, typically their partner, as a decision-maker in the process [P15].

The third category was related to the impact of other people’s experiences on the participants’ preferences. Some participants reported that the experience of a family member or peers (individuals who have used preventive LMWH in their pregnancy) was important to them. Learning about other patients’ experiences helped them know what to expect, and ultimately affected their final decision [P14] [P2].

Agency

The agency preferences refer to the medication itself (preferences towards daily injections) and preferences were classified into two attributes: 1) benefits and 2) drawbacks of daily injections with LMWH.

The most reported benefit associated with daily use of LMWH was that ‘LMWH prevents experiencing a VTE event’ [P6]. Other benefits were: ‘No harm for the baby’ [P2]; having ‘more regular check-ups of their pregnancy’ [P13] [P10]; ‘perception of low bleeding risk’[P2]; ‘perception that LMWH has the effect to prevent miscarriage’ [P9]; and, ‘can stop the medication immediately’[P11].

In contrast, these participants identified six barriers that negatively influenced their decision to use LMWH daily during pregnancy. These included: ‘scheduling injections’ being the most prominent [P12], followed by: ‘pain, bruising and aesthetics’ [P9] [P1]; ‘low perceived efficacy of the treatment and low quality of the evidence for recommending its use’ [P14]; ‘planned delivery and concerns regarding the timing of epidural analgesia’ [P8] [P10], ‘concerns with bleeding, and perception of risk to the unborn child’ [P6] [P3], ‘not liking needles’ [P6], and ‘needing help to administer the injections’ [P15].

Although actions were involved in this agency motive, they can be differentiated from the act motive as it doesn’t refer to actions regarding the decision of using anticoagulation treatment vs. other alternatives, but on attributes of the LMWH medication itself.

Purpose

For purpose, 17 preferences were collected, making this motive the least prominent. Half of the participants clearly expressed a motive for their final goal of the decision of taking LMWH during pregnancy. The most reported preference for this motive was risk avoidance by taking LMWH; participants reported their main goal was to avoid the risk of another VTE event during pregnancy [P8], [P2]). Other participants reported that their goal was to avoid the risk of death [P1]. Few participants reported that their main goal was to be a mother [P4]. The second preference was peace of mind. Some participants expressed that taking LMWH gives them peace of mind and makes them feel they are doing something to prevent the risk [P14].

Table 4 summarizes the findings described previously for each of Burke’s pentad motives.

Table 4 Summary of the main categories of each of Burke’s pentad motivesMixed-methods integration dataSociodemographic and clinical variables for each of Burke’s pentad of motives

For each of the participant’s sociodemographic and clinical variables, we reported the number of preferences for each of Burke’s pentad motives (see Table S1 in Supplementary Material 2). We observed higher frequency of preferences among participants with higher education level, not pregnant at the moment of the decision-making, at higher risk of recurrent VTE, whose previous event was DVT, and from Spain vs Canada. However, no significant differences were observed in these associations.

Health states with Burke’s pentad of motives

We integrated the results from the health state preference elicitation exercises with the preferences categorized in Burke’s pentad of motives and represented the findings using a side-by-side comparison (Table 5).

Table 5 Side-by side comparison between health states (quantitative data) and Burke’s pentad of motives (qualitative data)

The health state “using daily injections of LMWH” was the closest to the best health state- ‘healthy pregnancy’ according to the rank ordering and VAS exercise, and was the health state that showed highest utility value. The motives were concordant with these ratings except for agent and agency preferences. Discordant agent preferences were related to the experience of others making them fear having to use daily injections (e.g. one participant that rated daily injections with LMWH as the best health state also said “the experience of a colleague of mine that had many inconveniences. She was terrified of sticking (a needle) in her pregnant gut” [P12]). Discordant agency preferences included participants reporting more drawbacks than benefits of using daily injections, suggesting their experience was further from having a ‘healthy pregnancy’ (“To be puncturing every day, also puncturing to puncture, because the effect is not much” [P13].

The health state ‘experiencing DVT in pregnancy’ showed the second closest to ‘healthy pregnancy’ for the rank ordering and VAS exercise and second highest utility value. All the motives were concordant with this rating; for example, ‘scene’ preferences reported that participants had more fear of experiencing bleeding and a pulmonary embolism than experiencing DVT. Similarly, participants reported the ‘purpose’ of having ‘peace of mind’ while using LMWH rather than risking DVT (“For me, it gives me more peace of mind to put it on, because even if I have to prick myself every day, I stay calmer that way” [P14]). There were no ‘agent’ motives reported for this health state.

For the health state ‘experiencing a major bleeding during delivery’ there were few motives specifically addressing bleeding that would justify the ratings for this health state (third in the rank order and VAS, and second lowest utility value. ‘ Agent’ preferences reported how the experience of family members experiencing major obstetrical bleeding led them to decline LMWH. Preferences from the motive ‘agency’ showed discordant arguments: while some participants reported that they perceived there was a low risk of bleeding, other women were concerned about LMWH prophylaxis causing bleeding.

For the health state ‘Experiencing pulmonary embolism in pregnancy’ the rating was closest to death according to the rank order and VAS exercises, and presented the lowest utility value. All the motives were concordant with this rating. In particular, the ‘scene’ preferences revealed a stronger desire to use LMWH since experiencing pulmonary embolism was a very traumatic situation that participants do not want to go through again. Similarly, they reported as a ‘purpose’ to avoid risk of death, showing a strong agreement with the scores (“for me it was a very traumatic event, another person who has had the clot in the leg would be less scared, but in my case it was in the lung, I could have died” [P14]. There were no ‘agent’ motives reported for this health state.