<|BOS|> non-responders (M = 22.46 years and M = 18.92 years, respectively; 95% confidence interval for mean difference: 0.42 – 6.66).
Individual-level and [practice-level] response rates, DREAM survey.
Chi-square analyses of responders showed no association between trial group (intervention versus control) and the following variables: diabetes register, number of GPs in the practice, number of nurses in the practice, prescribing status of nurses, and years since qualified (all p > 0.3). Nevertheless, as this was a process evaluation of a trial, the remaining descriptive analyses were conducted separately for intervention and control participants.
Bivariate correlations between the direct measures for each of the three behaviours are presented, separately for the intervention and control groups, in Table 2. Means, standard deviations, and correlations between the direct and indirect measures of the same construct are also included. These correlations may be used to assess the content validity of the indirect measures. If the indirect measures were individually relevant and together adequately represented the range of beliefs, this should result in moderate-to-strong positive correlations between direct and indirect measures. Using this criterion, validity of the indirect measures was acceptable for attitudes and subjective norms, but questionable for PBC. That is, it is possible that, to create a questionnaire of acceptable length, we may have excluded important control beliefs that influence clinicians' perceptions of control over these behaviours.
Means, standard deviations (SD), and correlations between the predictor variables (direct measures) and intention scores and indirect measures, for each of the three behaviours, computed separately for the intervention and control groups.
PBC = Perceived Behavioural Control; Subj Norm = Subjective Norm.
Lower mean scores reflect stronger positive attitudes towards the behaviour, stronger perceived social pressure to enact the behaviour and greater perceived control over the behaviour.
There was no main effect of trial group and no interaction effects involving trial group on the profile of TPB scores. That is, the intervention appears to have had no effect on scores for attitudes, subjective norms, PBC, or intentions. However, there was a main effect of practice size on intentions. Responders (both GPs and nurses) in smaller practices had stronger intentions to measure blood pressure. In addition, there was a main effect of job title (GP; nurse) on cognitions. Nurses had more positive intentions and attitudes than GPs for measuring BP and examining feet. The pattern for statins was reversed, with GPs reporting stronger intentions, more positive attitudes, and also greater PBC than nurses. This again lends support to the criterion validity of the PBC item, as it would be expected that nurses, most of whom are not eligible to prescribe, would report lower control over prescribing behaviour. No other main effects or interaction effects were significant in the MANOVAs.
A multiple linear regression analysis on intentions for each of the three behaviours was carried out separately for the intervention and control groups (Table 3). At the first step, the direct measures of Attitude, Subjective Norm, and PBC were entered; indirect measures were entered at the second step. This was to check whether the solution would change depending on which method of measurement (direct or indirect) was used. In the intervention group, the addition of indirect measures did not improve prediction of intention for any of the three behaviours. In the control group, the addition of indirect measures did not improve prediction of intention to prescribe statins or to examine feet. However, prediction of intention to measure blood pressure did improve when indirect measures were added (R2 change = 0.14, p < 0.05). The significant predictor at the second step was attitude (indirect), β = 0.47, p = .002. Although this finding relates to only one of six regression analyses performed, it suggests the possibility that clinicians in the control group and intervention group may have been thinking about their beliefs and intentions in different ways.
Results of regression analyses on intentions for three behaviours, with direct measures entered at Step 1 and indirect measures entered at Step 2, for control and intervention groups.
PBC = Perceived behavioural control.
We performed a second series of hierarchical regression analyses, with professional (GP or nurse) and practice size (< 4 GPs; ≥ 4 GPs) entered at the first step and the direct TPB measures entered at the second step. After controlling for job title and practice size, the TPB predictor variables again significantly added to the variance in intention explained, and the patterns of significant predictors were similar to the first set of analyses. This finding was consistent in both the control and intervention group for all three behaviours.
Table 3 shows a consistent pattern that may represent an effect of the intervention. Specifically, for inspecting feet and prescribing statins there was a trend for intentions to be predicted most strongly by subjective norms in the control group and by attitudes in the intervention group. To determine whether these trends were reliable, two further hierarchical regression analyses were