Of 893 potential participants with a scheduled baseline visit, 193 did not attend their appointment and 150 did not have peripheral arterial disease. Of the remainder, 195 were excluded (), leaving 355 participants. Of these, 209 were recruited in Chicago and 146 in Worcester.
STUDY PARTICIPATION AND FOLLOW-UP RATES
Participants randomized to usual care had a higher prevalence of baseline cholesterol lowering medication use (). Completed call rates were 87.6% and 82.3% in the intervention and attention control conditions, respectively. Telephone call durations were 28.4 ±4.5 and 21.2±4.1 minutes, respectively.
Baseline Characteristics of Randomized Participants According to Group Assignment (n=355).
At twelve-month follow-up, LDL-cholesterol levels were obtained for 85.8%, 92.5%, and 90.2% of participants in the intervention, attention control, and usual care conditions, respectively. Three participants in each condition died during follow-up. No serious adverse events were attributed to study participation. Participants who dropped out were older (p=0.041), had lower education (p=0.008), a higher prevalence of lung disease (p=0.006), and were more likely to report no alcohol consumption (p=0.022) than those completing follow-up.
At twelve-month follow-up, mean LDL-cholesterol changes were −18.8, −6.8, and −11.1 mg/dl in the intervention, attention control, and usual care conditions, respectively (overall p value =0.035), adjusting for baseline LDL-cholesterol (). The attention control condition had less LDL-cholesterol decline, compared to the intervention (+10.5, 95% Confidence Interval (CI) =+2.5 to +18.4, p=0.010). Participants in usual care had less LDL-cholesterol decline compared to the intervention, but this finding was not statistically significant (+5.1, 95% CI =−2.9 to +13.1, p=0.208) (). These differences remained similar even after adjusting for baseline differences in cholesterol-lowering medication use. Sensitivity analyses demonstrated comparable estimates and identical statistical conclusions.
Associations of A Telephone Counseling Intervention on Primary and Secondary LDL Cholesterol Outcomes in Peripheral Arterial Disease Participants
At twelve-month follow-up, changes in proportions of participants with LDL-cholesterol levels <100 mg/dl were +21.6%, +9.0%, and +9.1% in the intervention, attention control, and usual care conditions, respectively (overall p-value=0.009) (). Compared to the intervention, participants in the attention control condition (p=0.003) and usual care (p=0.018) were less likely to have an LDL-cholesterol < 100 mgs/dl ().
Mid-way through the intervention, at six-month follow-up, mean LDL-cholesterol changes were −14.4, −6.6, and −8.8 mg/dl in the intervention, attention control, and usual care conditions, respectively (overall p value =0.193).
At twelve-month follow-up, participants in the intervention had greater increases in use or dose intensity of cholesterol-lowering medication than participants in the attention control and usual care conditions, respectively (+54% vs. +18% vs. +31%, p<0.001), adjusting for baseline use of cholesterol-lowering medication (). Intervention participants were more likely to add a cholesterol-lowering medication or increase their dose, compared to those in the attention control (p=0.001) and usual care (p<0.001) conditions, respectively. At twelve-month follow-up, relative to the intervention, participants in the attention control and usual care conditions had less improvement in the PAM score (p=0.016 and p=0.007, respectively), less improvement in the PEPPI score (p=0.014 and p=0.015, respectively), less improvement in their health knowledge score (p<0.001 and p<0.001, respectively), and lower increases in the proportion who agreed with the statement, “it is my responsibility to bring up my cholesterol treatment with my physician” (p=0.001 and p=0.009, respectively) ().
Associations of a Telephone Counseling Intervention with Exploratory Outcome Measures at 12-Month Follow-up in Peripheral Arterial Disease Participants
There were no differences in changes in adherence to cholesterol-lowering medication or percent of calories consumed from saturated fat between the three conditions ().