On the use of the Trans-Theoretical Model for Blood Donation among Spanish Adults

Background Relying solely on altruistic appeals may fail to full the increasing demand for blood supplies. Current research has largely been attempted to determine and understand motives that serve as blood donation drivers. The Trans-Theoretical Model of behaviour change (TTM) can be used to conceptualise the process of intentional blood donation behaviour. Methods A cross sectional survey of Spanish adults was conducted. The nal sample consisted of 504 individuals who were administered a self-report questionnaire including the measures of demographic characteristics, Stages of Change, Processes of Change, Self-ecacy and Decisional Balance. Data were analysed by frequency analysis, MANOVA/ANOVA and correlation analysis. Results Findings indicated that most of the behavioural and cognitive processes of change, self-ecacy and physical cons differentiated participants across the stages of change of blood donation. In contrast, eligibility cons and pros were less inuential in stage transitions. Furthermore, signicant correlations were observed between TTM constructs except for the physical cons and the processes of change. Conclusions The present study extensively supports and replicates the applicability of the TTM to blood donation behaviour change and offers important implications for the development of effective stage-matched interventions to increase blood donation.


Introduction
In recent decades, researchers have identified a range of sociodemographic, organizational, psychological and physiological factors that impact the individual's willingness to donate blood [1][2][3] . Although blood donation (BD) is considered as a purely prosocial behaviour, altruism and empathy were portrayed among the less significant motivations driving the BD decision 4 . Different theories and models of behaviour change have been applied to health contexts to assist in the design of behaviour change interventions. In this respect, six main theoretical perspectives to boost adherence to health behaviours have been identified (biomedical, behavioural, communication, cognitive, selfregulatory and stage perspectives) encompassing, each of them, different theories 5 . The most recurrently used theories are those within cognitive and stage perspectives 5 . The cognitive perspective includes theories that consider attitudes and beliefs as the locus of the individual's behaviour. Of those theories, the Theory of Planned Behaviour (TPB) is the most widely cited and applied theory in predicting BD behaviour and intentions 6 . On the Page 3/21 other hand, stage-based theories contend that individuals go through distinct stages as they learn and develop. The Trans-Theoretical Model (TTM) is the most prominent and widely applied among stage models 7 . Originally developed to assess the individuals' readiness towards smoking cessation 8 , the TTM has been recently applied in distinct cultures and ethnicities 9,10 over numerous health behaviours 11  Whilst, individuals in maintenance stage are being more confident to maintain the desired behaviour and are less tempted to relapse.
Ten processes of change have been suggested to help people move through the change process and have been classified into two categories: experiential and behavioural 13 . The experiential Processes and are used primarily for the early stage transitions and those labelled behavioural Processes are used primarily for later stage transitions.
Further, the TTM was expanded to include two additional core constructs: Self-efficacy and Decisional Balance. The application of self-efficacy has been found to have numerous implications in predicting blood donor behaviour; it is expected to increase as people progress through the stages 14 . Nonetheless, it is particularly relevant at transition through the later stages 12 . Decisional balance reflects the individuals' relative importance of the cons and pros of changing a specific behaviour. Recent research suggested that individuals in the later stages endorse more positive aspects of change and more negative aspects in earlier stages 11 . Specifically, this study aims at applying TTM to BD behaviour among a Spanish population. To this end, five research questions (RQ) are investigated: How are the recruited participants distributed over the five stages of change? Page 4/21 How do the Processes of Change vary across stages of change?
How do and Decisional balance (Cons/Pros) differ across stages of change? How does Self-efficacy vary/differ across stages of change?
How is the correlation between the POCs and Decisional balance, and POCs and Selfefficacy?
The major contributions of this cross-sectional study are the following: 1) Developing measure scales for TTM constructs including Stages of Change, Processes of Change, Decisional balance and Self-efficacy; 2) Determining the staging distribution of the recruited sample using an algorithmic approach; 3) Establishing patterns of the four TTM constructs by Stages of Change.
The structure of the paper is as follows: 'Materials and Method' section describes the empirical methodology followed throughout this study. The results of the statistical analysis are provided in 'Results' section. 'Discussion' section thoroughly discusses the findings and presents the threats to validity of this study. Finally, conclusions and some directions for future work are outlined in 'Conclusion and future work' section.

Materials And Methods
This section presents the empirical design of the study, starting with the description of the recruitment phase of the survey respondents. Categories of the questionnaire are explained next and a description of statistical procedures used in this study are outlined at the end of this section.

Participants and design
This study is cross-sectional in design and consisted of the dissemination of a paper-based survey. All the procedures employed in this study were approved by the Ethics Committee of the University of Murcia. The recruitment phase led to the enrolment of 602 participants Page 5/21 from the University of Murcia and Reina Sofia Hospital in Murcia. A total of 158 first and second-year students from the Faculty of Nursing were approached during lectures and were asked to fill in the survey. The remainder of the sample (N=444) was recruited at Reina Sofia Hospital where hospital staff, patients and their companions were handed the same questionnaire to fill in after giving their written informed consent to take part in this study. The questionnaires were completed under the supervision of the researcher who resolved any doubts. All participants were assured of anonymity and confidentiality.

Measure development
The study was quantitative, with data gathered through self-administered questionnaires.
These questionnaires were designed such that they help to measure the four constructs of the TTM. A review of the literature in TTM and BD was conducted and integrated into the development of the questionnaire's items to derive salient beliefs about BD 2,3,5 . An adaptation to previous measures in BD and other content areas 15-17 , 12,18 was made to refine the items. The resulting questionnaire was translated into Spanish and consisted of five categories:

a) Demographic characteristics
Various socio-demographic characteristics were assessed including age, gender, marital status and education level. Participants were also asked about their blood type.

b) Stage of Change
Participants were asked to answer a short series of questions regarding their past BD behaviour and their future intention to donate. A staging algorithm was developed and followed to place the participants in one of the five stages of change as shown in Figure 1.

c) Processes of Change
A total of thirty items representing the ten Processes of Change (three items per process of change) were randomly comprised into the questionnaire. Participants were given a fivepoint scale ranging from "Never" to "Repeatedly" to rate the frequency in which they make use of a situation, thought and feeling to enhance their readiness to donate blood. Table A1 in the appendix presents the description and the three proposed items for each process of change.

d) Self-efficacy
Self-efficacy is a measure of the extent to which an individual is confident in their ability to donate blood in the face of prospective hard situations. Eight items were designed to develop the self-efficacy scale as shown in Table A2 in the Appendix. Responses were made on five-point scale, ranging from 1=" Not at all confident" to 5=" Extremely confident".

e) Decisional Balance
Twelve items were designed to assess how an individual evaluates the pros and cons of BD.
Six items were employed to reflect the Pros of BD and the remaining six items were evenly distributed among Physical Cons and Eligibility Cons as depicted in Table A3 in the Appendix. Participants responded on a five-level scale ranging from 1=" Not at all important" to 5=" Extremely important" to rate the importance of each item in their decision to donate blood.

Results
This section presents the statistical outcomes of the analyses conducted in this study.

Sample
Of the 602 participants, 98 individuals were excluded from further assessment as they failed to answer (either by refusal or answering 'I don't know') to the question concerning their eligibility to donate blood. The remainder sample (N=504) was predominantly constituted by female (62.9%), and ages ranged from 18-80 with a mean of 27.32 (SD=11.134). Table A4 in the appendix depicts the frequency distribution of the recruited sample in relation to the demographic characteristics.

Stages of change
All 504 participants were placed into four exclusive categories based on their responses to the algorithmic staging questionnaire. The distribution by stage of change for the entire sample was as follows: Pre-contemplation 36.9% (N=186), Contemplation 41.7% (N=210), Preparation 9.3% (N=47), Action 10.3% (N=52) and Maintenance 1.8% (N=9). Preparation (p=.069). A graphical representation of T-scores on the decisional balance scales across the stages for BD is shown in Figure 4.

Self-E cacy by Stage of Change
Self-efficacy scores yielded statistically significant differences across the five Stages of Change as shown in Table 2. Post-hoc Tukey tests were performed to examine Self-efficacy mean comparisons across the five Stages of Change. The results revealed that Self-efficacy scores were significantly higher in Action and Maintenance stages than in Precontemplation Stage. The variation of Self-Efficacy T-scores across stages is graphically shown in Figure 5. Processes of Change, Decisional Balance and Self-E cacy Table 3 illustrates the results of the correlation analysis to assess the relationships among the TTM constructs. Note. ** . Correlation is significant at the 0.01 level (2-tailed)

Discussion
This section discusses and interprets the findings of this study based on the five predefined research questions and outlines the threats to validity of this study.
How are the recruited participants distributed over the five stages of change?
The Stages of Change construct is one of the pillars of TTM theory. It reflects the individual's motivational readiness to make a specific behaviour change. Accurate staging is perhaps the most crucial aspect of using TTM for developing health-related interventions 19 . To date, two major methods have been used for assigning stage classifications: staging algorithm and multidimensional questionnaire 20 . The staging algorithm approach uses a small number of questionnaire items to determine the participant's stage. In the second approach, each Stage of Change is measured through a set of questionnaire items. The staging algorithm used in this study to classify participants into one of the five stages of change depends on the assessment of recent past behaviour and the willingness to change behaviour. In fact, in order to be allocated to one of the earlier stages (Pre-contemplation, Contemplation, Preparation), participants are required to state their intent to donate blood in the near future. Nevertheless, Action and Maintenance stages require the demonstration of both intention and regular past experience of BD. Research suggests that past behaviour is a significant predictor of future behaviour for regular and experienced donors (5 or more previous donations), and intentions were predictive of occasional donors (4 or fewer previous donations) 21,22 . Consistent with previous research (e.g. 9,23 ), participants in this study were predominantly categorized into the pre-preparation stages accounting for 78.6% which mirrors the deterrence of participants in donating blood and the need to trigger a range of motives to induce progression across stages of change.

How do the Processes of Change vary across Stages of Change?
Previous studies based on TTM demonstrated that experiential processes benefit progression through the earlier stages of behaviour change while behavioural processes Page 11/21 have greater importance during later stages. In the current study, both sets of Processes of Change were significantly lower for individuals in Pre-contemplation than those in further stages. This result supports the hypothesis of the TTM, which is that the more advanced an individual is in Stage of Change, the more frequently they will use the Processes of Change.
Indeed, pre-contemplators are unmotivated and unaware of the need to change, thus harnessing fewer strategies towards behaviour change 12,24  How does Self-efficacy vary/differ across stages of change?
Another major construct of TTM is Self-efficacy which refers to the perception and situational confidence that individuals have in their abilities to adopt and maintain the desired behaviour change even in difficult circumstances that often trigger relapse 31 .
Research on TTM suggests that Self-efficacy increases in an almost linear fashion as the Stages of Change advances. Consistent with this, the Self-efficacy scores in the present Page 13/21 study varied and rose significantly across stages. Contemplators had higher baseline of Self-efficacy scores than pre-contemplators and lower level than participants in advanced Stages of Change. In addition, participants in Preparation stage reported similar level of confidence to those in Contemplation stage. Perhaps individuals in preparation stage demonstrate ambivalence about their readiness to engage in the behavioural change.
Moreover, participants identified in action and maintenance stages expressed the highest levels of self-efficacy with regard to BD in high-risk situations. This indicates that Selfefficacy is strongly influenced by performing the behaviour and that individuals in later stages are, by default, acting towards the behaviour change. The results obtained in this study provide evidence supportive of the applicability of the self-efficacy construct to actively change BD behaviour.
How is the correlation between the POCs and Decisional balance, and POCS and Selfefficacy?
With respect to the associations among the TTM constructs, significant positive correlations were observed between the two dimensions of Processes of Change and Pros and Selfefficacy. Hence, TTM-based interventions that promote the usage of behavioural and cognitive Processes of Change should increase Pros and Self-efficacy accordingly.
Eligibility cons were positively related to all TTM constructs and particularly to the pros of donating. A possible explanation is that even though individuals have eligibility concerns to donate blood, they outbalance their perception of the benefits of donating over these concerns. Moreover, scores on both cognitive and behavioural processes were not correlated with physical cons of BD Consistent with this outcome, many studies have reported that physical concerns are less prominent in behaviour change 11,32 . Additionally, a significant negative correlation was found between self-efficacy and physical cons.
Therefore, it may be the case that as individuals gain confidence in their ability to donate blood, they start to attach little importance to the associated physical barriers. The highest correlation was found between the two dimensions of Processes of Change further supporting prior studies in which a tight association was perceived among processes 33 .
Despite the interest of this research, a number of threats to validity of the conclusions reported are worth highlighting.
Construct validity. Due to the lack of a standardized measurement instrument for stage classification, the validity and reliability of staging algorithms have not yet been established 34 . To mitigate this threat, the staging algorithm used in this study was elaborated on the basis of validated measures 9,18 . Moreover, the items developed to measure Processes of Change, Decisional Balance and Self-efficacy were derived from a selection of validated TTM measures in various health behaviours including BD.
Internal validity. The internal validity of the present study could be threatened by a bias towards the instrumentation adopted. In fact, the questionnaire used in this study to gather data relied on a self-report format, leading to possible response bias due to a lack of validity and reliability 35 . Nevertheless, self-report measures are largely considered as a pertinent tool in health behavioural research 36,37 .
External validity. In this study, the size of the final sample was convenient, however, it comprises somewhat a restricted range of donors in advanced stages which was not representative of the rest of the blood donors' population. This may jeopardize the generalizability of the findings of this study. It is, therefore, necessary to conduct further assessment that includes greater percentages of regular donors to benefit the yielded measures.

Conclusions And Future Work
To the best of our knowledge, this is the first cross-sectional study to apply the Trans-Theoretical Model to BD behaviour within a Spanish population. The main purpose of the current study was to explore relationships among TTM constructs in a Spanish population with regards blood donation behaviour change. As behavioural and experiential Processes of Change, Self-efficacy and physical cons were found to be consistent variables of progression through stages of change for BD behaviour. However, concerns related to eligibility and perceived benefits of blood donation were influential in stage transitions. Page 15/21 Overall, the results obtained are in general accordance with findings reported in previous studies and therefore, the applicability of TTM to BD behaviour is supported. More importantly, the current study offers important practical implications for the field of BD.
The measures developed in this study can serve as a starting point for development of stage-matched interventions aimed at increasing blood donors' intention.
Future work in this area should adopt a longitudinal perspective with a more evenly distributed sample of donors to explore in-depth how TTM construct help donors evolve across stages of change. Another potential future direction should focus on identifying strategies that harness Processes of Change, Decisional Balance and Self-efficacy for the development of TTM-grounded and appropriately tailored interventions targeted to blood donors. In this respect, persuasive strategies can play a paramount role in promoting behaviour change in these interventions.

Data Availability
The datasets generated during the current study are available from the corresponding author on request.     Self-E cacy scale across Stages of Change.

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. supplement1.docx