A total of 3,522 patients with CHD who enrolled in the study between 2001 and 2003 were randomized to control or intervention groups, with 2,787 retained in the study at 12 months and included in the data analysis (). Patient characteristics according to study group are shown in . Patients had a mean (SD) age of 67.2 (11.0) years and mean (SD) BMI of 27.5 (5.0) kg/m2. Groups were similar at baseline except for small differences in the proportion of females, the number insured for ambulance use and the number who had attended a cardiac rehabilitation program. The proportions of patients with self-reported risk factors for CHD and previous cardiovascular diagnoses were high in both groups. Most had a cardiologist involved in their care and many reported symptoms of anxiety (MAACL Anxiety subscale ≥ 7) and depression (MAACL Depression subscale ≥ 11). With a possible range of scores of 8 to 40, patients in both groups had moderately high levels of perceived control (control = 30.40 ± 4.01, intervention = 30.18 ± 4.27, p = .11). In the control group, 21.3% of study participants had a family member present with them during the baseline study visit, compared to 24.4% in the intervention group (p = .076).
Diagram of flow of participants through the study
Baseline characteristics of study participants by group and of those lost to follow-up at 12 months.
The characteristics at baseline of participants on whom there was no follow-up at 12 months are also shown in . Participants lost to follow-up were younger, less likely to be married or Caucasian, had higher levels of education and private health insurance, and a worse cardiac risk factor profile, including more frequent symptoms of depression. Compared to the intervention group, control group patients lost to follow-up had marginally higher perceived control scores (30.11±4.10 vs 29.02±4.68, p=.002) and were less likely to have anxiety symptoms (42.6% vs 51.5%, p=.029). There were no other statistically significant differences between groups on patients with no 12 month follow-up.
3.2. Knowledge, attitudes and beliefs
The knowledge, attitudes and beliefs scores were normally distributed at each time point. Knowledge, attitudes and beliefs scores on the ACS Response Index increased significantly in the intervention group at 3 months and remained higher than control group scores at 12 months (). Between group comparisons using repeated measures ANCOVA for continuous variables showed that:
ACS Response Index scores for knowledge, attitudes and beliefs at study entry, 3 months and 12 months
i) Knowledge remained significantly higher in the intervention group over time after controlling for covariates (p < .0005); higher baseline attitudes scores (p < .0005) and baseline beliefs scores (p < .0005) were significantly associated with better knowledge; older age (p < .0005) and higher baseline anxiety (p = .048) were associated with lower knowledge scores.
ii) Attitudes remained significantly higher in the intervention group over time after controlling for covariates (p < .0005); higher baseline knowledge scores (p < .0005), baseline beliefs scores (p < .0005) and perceived control (p < .0005) were significantly associated with more positive attitudes; older age (p < .0005) and higher baseline anxiety (p = .048) were associated with lower attitudes scores.
iii) Beliefs also remained significantly higher in the intervention group over time after controlling for covariates (p = .006); higher baseline knowledge scores (p < .0005) and baseline attitudes scores (p < .0005) were significantly associated with higher beliefs scores; older age (p = .004) and higher baseline anxiety (p < .0005) were again negatively associated with beliefs scores.
Repeated measures factorial ANOVA for categorical variables showed that:
i) Knowledge increased over time if patients had attended cardiac rehabilitation in the past (p = .002), were female (p < .0005), were in paid employment (p < .0005), had higher levels of education (p = .003) and had any private health insurance (vs. government only or no insurance; p = .047). Time, study group membership and history of stroke had interaction effects on knowledge (decreased knowledge; p = .022), as did time, study group membership and being insured for the ambulance (increased knowledge; p = .034).
ii) Attitude scores increased over time when a family member was present during the baseline visit (p = .017), and when the patient had a history of angina (p = .017) or percutaneous coronary intervention (p = .036). There were interaction effects on attitudes of time, study group membership and having any private health insurance (p = .017) and a history of percutaneous coronary intervention (p = .025), both of which were associated with higher attitudes scores.
iii) Beliefs scores increased over time when patients had a history of angina (p = .014) and had been to cardiac rehabilitation (p = .019), but there were no significant interaction effects between time, study group membership and any factors studied.