Developing attributes and levels for the DCE study

For the purpose of this study, we needed to develop attributes, together with their corresponding levels, that successfully described the different aspects, properties and characteristics of the electronic discharge summaries sent by the doctors working at the hospital, and which were of importance to the majority of GPs when they make a decision about their preference for the given alternatives (142).

In order for the study results to be applicable to the DCE research question, the attributes developed for this study needed to be relevant, measurable and mutually independent (136). The minimum number of attributes possible to describe the summaries should be identified, and there is a consensus that no more than eight attributes should be used within a DCE (136). However, if attributes that are significant (or relevant) to the decision-making behaviour of respondents are omitted, this could lead to inferences being wrongly made, leading to bias in the results. Data regarding the relevance and significance of the

properties of a discharge summary needed to be generated from GPs themselves, expressed in their own words, in order to ensure that all attributes significant to them are identified and included.

The levels that each attribute may take should be plausible to the respondents, and pitched such that the respondents are willing to trade between combinations of the attributes (142). They can be described quantitatively or qualitatively, depending on the attribute to which they are attached. Each attribute may take a different number of levels and intervals if necessary to describe its range of values (e.g. 24 hours, 48 hours, 72 hours) or where a binary choice is desirable (e.g. yes or no). In this study, after having identified the attributes relevant to GPs, a range of realistic values that each of these attributes may take should again be generated from GPs themselves; using their experience working with discharge summaries to describe the levels of attributes which are ideal, acceptable and unacceptable in practice.

The importance of well researched and thorough attribute development has been highlighted in the literature (140, 142). Methods commonly adopted to identify attributes for DCEs include literature reviews, existing health outcome measures, professional recommendations, and qualitative research in the form of focus groups, interviews and surveys (141) with service users or subject experts. However, the process by which attributes are developed for DCEs is often poorly reported (141), and so in the next two chapters we aim to provide a detailed description of the processes used to construct and refine attributes to be used within a DCE. Many qualitative research approaches emphasise and support the production of rich description of the processes they entail and are therefore relevant here.

5.5.1 Qualitative methods to identify attributes

Qualitative methods, such as surveys, interviews and focus groups, are of particular use in DCE attribute development because they are able to generate data from the perspective of respondents in their own words, allowing the researcher to understand how the respondents evaluate and express levels for the subject being investigated (162), and providing the ability to exclude potentially irrelevant or confounding attributes.

In 2011, Coast et al. (141) reviewed eight Discrete Choice studies which had used qualitative methods to identify attributes in their design, including focus groups, interviews

and meta-ethnography, and the relevance of their findings for this study are considered here. Whilst authors concluded that attributes could be most successfully identified through a combination of different qualitative techniques, in-depth interviews were considered as being particularly suitable as they allow enough time for thorough and detailed exploration of concepts. Focus groups, whilst found useful to promote discussions between participants which may uncover topics that the researcher may not have considered, were also found to allow less time for in-depth exploration and could be less appropriate where discretion or confidentiality may be desired. In the case of this study, it would have been interesting to promote discussions between different GPs practicing within the area and to hear their contrasting ideas, but because they will know each other already in a professional manner there may be dynamics within existing relationships which might steer or influence the willingness others to participate. The usefulness of meta-ethnography as a method to develop attributes is largely dependent on the extent of existing literature in the subject area, and although the transfer of patient care in general is a topic well researched quantitatively, there is little existing research on the preferences of GPs at discharge; and so would not be a suitable method for attribute development in this study.

With respect to analysis, Coast et al. concluded that iterative constant comparative approaches to analysis were most efficient because they allow interview questions with successive interviewees to be continually adapted in the light of the findings being generated (141, 163), which for a DCE, will allow for the attributes to be sequentially rounded and refined further as the study progresses.

5.5.2 A two-stage process

Coast et al. also recommended a two-stage approach to attribute development:

conceptualisation of the attributes of the service in question; and refinement of attributes to convey meaning to the study participants. Conceptualisation consists of gathering the relevant and important characteristics of a service, often in academic terms appropriate to the researcher or policy maker.

The equivalent first stage in this study was a survey to GPs, which aimed to conceptualise the discharge process by asking GPs to rank a selection of components and characteristics of discharge summaries in order of importance to them.

The second stage was a qualitative study, which aimed to refine the significant characteristics of the service, in their raw state, to be shaped into attributes that convey the intended meaning to participants in a DCE. A secondary aim for this study was to further explore the perceptions of GPs on discharge from secondary care and to understand their expectations for discharge communications and why.

5.6 Conclusion

This chapter has identified DCEs as an appropriate and useful technique for investigating patient, consumer and provider preferences in healthcare settings. Application of DCE is therefore relevant to the research objective to explore GP preferences and expectations from secondary care providers at discharge. Development of attributes to describe the discharge system in an appropriate and meaningful way to GPs is necessary to ensure the DCE is valid. Similarly, levels need to be pitched at plausible values in order that the hypothetical choice presenting in a DCE is realistic to GPs. Qualitative methods have been recommended for the purpose of attribute and level development and refinement.

The next three chapters of this thesis describe the development and application of the DCE, which aimed to mirror the exploratory qualitative work conducted with junior doctors at the other side of the interface (reported in Chapter 4). The overall aim was to investigate and understand the relative value that GPs place on the individual properties of discharge communications, and consequently, to identify which aspects of discharge need to be prioritised by doctors working in secondary care in order to meet GPs’ needs post discharge. Figure 5.4 below summarises the project method outline.

Figure 5.4: The six phases of DCE project development and location within this thesis

Chapters 6 and 7 describe the development of the DCE questionnaire using two stages: a service evaluation survey to GPs, which aimed to conceptualise the discharge process from

Conceptualisat

the perspective of GPs and to gather information on the important and relevant properties of discharge communications; and qualitative interviewing to refine and focus the concepts derived in the survey into key descriptors of discharge communications. Chapter 8 describes the design and application of the DCE questionnaire to GPs in the East of England.

Chapter 6: Surveys to junior doctors