Individualized methods

dentine hypersensitivity, comparing the then-test and ideals. These two methods detected changes in internal standards in opposite directions. Whereas the ideals showed an upward shift in participants’ internal standards, the then-test detected a downward shift, which may be explained by participants reassessing themselves retrospectively as better off than they did at the baseline when they overestimated the impacts of dentine hypersensitivity. Krasuska interpreted those findings as signs of the bias arising from the then-test as described by Norman (2003).

2.2.5.2.2 Individualized methods

Individualized methods attempt to capture the QoL parameters most important for each individual. Several methods have been developed to take individual priorities into account and translate them into relevant domains and anchors to obtain a single score. Those methods include the Repertory Grid Technique, Self-anchoring striving scale (Cantril’s ladder) or the Schedule for the Evaluation of Individual QoL (Schwartz and Sprangers, 1999). All require participants to define aspects or anchors important to their health.

Most QoL questionnaires use psychometric scales with anchors to quantify the responses. Those anchors can be defined by the researcher (i.e. fixed anchoring scales) or the participant (i.e. self-anchoring scales) (Hofmans et al., 2009). The labels in fixed anchored scales may have different meanings for each participant, but the numeric value assigned is regarded as the same. In self–anchored scales participants evaluate their status with a value defined by their own perceptions,

the purpose of the scale, participants are asked, for instance, about the ‘worst’ and

‘best’ life situation, health condition or quality of life.

Although these scales are useful at the individual level, they have disadvantages. They may increase the loss of participants because more cognitive effort is required to describe the anchor. Further, they can be affected by recency bias or the ‘present state effect’ which proposes that people use information on their current state to recall the previous state, thus if the person feels well at moment of the assessment, is likely that they infer that their health status has improved (Blome and Augustin, 2016). Studies suggest that self-anchored scales generated more positive ratings of physical health than fixed anchors if the participants describe their worst experiences first. In this sense, recent memories would be more readily available during the completion of the questionnaire and the tendency would be towards positive ratings (Acker and Theuns, 2010).

Only a few individualized methods have been used to evaluate response shift. The Schedule for Evaluation of Individual Quality of Life (SEIQOL) asks participants to nominate the cues they consider most important for their quality of life and to rate them according to their relative importance. Nominating different cues at each assessment may reflect reconceptualization, changes in the ratings of each cue may reflect recalibration, changes in the order of the cues, reprioritization (O'Boyle et al., 2000). Ring and colleagues (2005) assessed the QoL of 117 edentulous patients before and after receiving high quality conventional dentures. The SEIQoL identified reconceptualization and reprioritization response shift.

In the Patient Generated Index (PGI) the participant chooses five areas of their life affected by the condition under study, rates their ability in these areas

and then dispenses 12 tokens across these areas of importance. Assessing reconceptualization among persons with stroke during the first six months of recovery, Ahmed and colleagues (2005c) used the PGI and concluded that people reconceptualised and reprioritized domains of HRQoL over time. The information provided by PGI was counterbalanced by the added complexity of completing and interpreting such measures.

Korfage and colleagues (2007) proposed the rating of vignettes to assess response shift in patients with prostatic cancer. Vignettes described side effects such as urinary, bowel and erectile dysfunction as the most important to patients at 1 month post-diagnosis than 2 months pre-diagnosis. This change was interpreted as reprioritization among participants who became more aware after diagnosis of the risks of cancer treatment.

Although these methods can identify areas of response shift at a personal level, their results are not easily converted into numerical values (Barclay-Goddard et al., 2009a) and the analysis is more complex.

2.2.5.2.3 Idiographic approach

Closely related to the individualized methods, the idiographic approach (‘pertaining to self; one’s own, private or separate’) refers to aspects of the subjective experience that make each person unique (Pagnini et al., 2012).

Through the idiographic approach participants are asked to state personal goals in terms of situations they want to accomplish, solve or avoid, and which roles and relationships influence their life. After describing their goals, participants rate goal

dimensions (Rapkin et al., 1994). This information helps to understand the meaning of QoL for each person and assesses the effects that illness and treatment have on peoples’ lives (Morganstern et al., 2011).

The Schedule for Evaluation of Individual Quality of Life (SEIQoL) described previously as an individual method, is based on the idiographic method that analyses individual needs, belief and emotions (Ring et al., 2005, O'Boyle et al., 2000)

The QoL Appraisal Profile (QoLAP) is an idiographic instrument used as a semi structured interview schedule to address the four aspects of QoL appraisal process described by Rapkin and Schwartz (2004). Response shift is operationalized in terms of the residual variance in the QoL change scores that can be explained by changes in appraisal due to coping or other processes:

reconceptualization (changes in frame of reference), reprioritization (changes in sampling strategies and factors that determine the relative salience of different experiences), recalibration (changes in standards of comparison) (Schwartz et al., 2007).

There is little evidence assessing this instrument, but apparently it has acceptable content validity (Li and Rapkin, 2009, Morganstern et al., 2011, Schwartz and Rapkin, 2012). The interviews and codification of each question are complex and require considerable time and resources, which makes this method less convenient.

2.2.5.2.4 Qualitative approaches (direct questioning)

Individuals may be questioned directly about their HRQoL to assess aspects of response shift (Schwartz and Sprangers, 1999, Barclay-Goddard et al., 2009a).

Semi structured interviews with post stroke individuals completing the PGI were conducted by Ahmed and colleagues (2005c) to assess whether they had experienced response shift. Participants compared the areas provided in the PGI at follow-up and at baseline. Half of the participants completing the PGI were interviewed, but unfortunately, not everyone applied the effort needed to assess response shift. Many participants communicated very little during the interviews.

Gregory and colleagues (2005) interviewed twenty people with socially noticeable broken, decayed or missing teeth to find out how measures of oral health related quality of life (OHRQoL) varied between and within individuals. This study demonstrated that the relevance and meaning of quality of life changed over time, whether or not participants received treatment. The authors proposed 7 dimensions of oral health on which people changed in their ‘margins of relevance’.

These changes in the ‘margins of relevance’ can be seen as changes in internal standards. The margins ranged from super relevant to not relevant. Changes in the relevance of the dimensions were also identified and corresponded to reconceptualization of QoL. Thus, response shift occurred in relation to quality of life

Sinclair and Blackburn’s (2008) qualitative study examined coping patterns reported by women with rheumatoid arthritis. In their interviews women reflected on adaptive strategies, changing priorities and reframed their situations in ways