shows the baseline characteristics for subjects randomized. There were no significant differences between groups except in peak flow. We adjusted the analysis of lung function for peak flow and there were no differences between the adjusted and unadjusted analyses. There were no significant differences between the participants that were randomized and those that were not (n=11, data not shown). Electronic and diary adherence and peak flow data were compared to look for concurrence, but only the electronic data for both were used in the analysis. Retrospective analysis showed that adherence to diary keeping and peak flow measuring over time declined by 0.02% for intervention subjects and 0.12% for controls (p=0.10).
Baseline Sample Characteristics
Mean (±SD) adherence for the intervention and control groups at T0 was 82% vs. 80%, at T1 it was 82% vs. 77% and at T2, 77% vs. 73% respectively. Mean adherence did not differ significantly between groups but stayed consistently higher over time in the intervention group compared to controls. At the end of the study, median adherence was 86% for intervention and 76% for controls. Mean change in adherence decreased in both groups over time, less so in the intervention group, but the differences were not statistically significant (). Odds of maintaining ≥60% adherence over the intervention period increased 9-fold for the intervention group and no change in the control group (OR 9.2 vs. 0.4, p=0.02; ). At T2 the intervention group maintained 3-fold greater odds of ≥60% adherence.
The odds of being symptom free were significantly higher during the intervention and at end of study for the intervention group (T0 –T1 OR 2.2, p=0.01; T0–T2 OR 5.9, p=0.02) but the change rates were not significantly different between groups (). Mean change in symptom scores also decreased significantly for both groups over time and the change rates were not significantly different between groups ().
The odds of nighttime awakenings decreased significantly over time in the intervention group (T0–T1 OR 0.24, p=0.001; T0–T2 OR 0.17, p<.001) compared to no significant change in the control group (). The odds of experiencing nighttime awakenings due to asthma over the entire study decreased significantly in the intervention group vs. controls (T0–T2 OR 0.17 vs. 0.77, p=0.03).
The incidence of rescue beta agonist use decreased significantly during the intervention period in intervention vs. control subjects (T0–T1 IRR 0.56, p<0.001; ). Both groups decreased beta agonist use over time with no significant differences between groups by T2.
Pre-bronchodilator FEV1 % predicted improved in both groups during the intervention period and over the period of the entire study with no significant differences between groups (). Post-bronchodilator FEV1% predicted improved in the intervention group at all time points and declined in the control group with no significant differences between groups. Morning peak flow improved significantly for the intervention group compared to controls during the intervention period (T0–T1 20.9 L/min., p<0.001 vs. 11.5 L/min., p=0.052) and both groups improved by end of study (T0–T2 29.6 L/min., p<0.001 vs. 24.5 L/min., p=0.004) with no significant differences in the change rates between groups ().
In the intervention group perceived control of asthma improved significantly during the intervention period (T0–T1 1.89, p<0.001 vs. 0.53, p=0.37) and during the entire study (T0–T2 2.87, p<0.001 vs. 0.68, p=0.25; between group difference, p=0.006, ). Quality of life scores improved significantly in the intervention group from T0–T1 (−2.71, p=0.01) and T0–T2 (−3.82, p<0.001) compared to no change in the control group; between group difference for T0–T2 showed a trend favoring the intervention (p=0.07).
Eosinophils (%) and tryptase (μg/L) were highly skewed and converted to binary variables; positive for eosinophils if total cell count was above the lower limit of detection (positive >1/500cells) and positive for tryptase if total concentration was above the lower limit of detection (positive > 1μg/L). Neutrophils (%) and ECP (ng/mL) were reported as means. There were no significant differences in the odds of eosinophils being positive within groups or between groups. Likewise, there were no significant differences within or between groups in ECP. There was a significant decrease in the odds of tryptase being positive for the intervention group T0 to T1 (OR 0.06, p=0.02) and an overall decrease from T0 to T2 (OR 0.003, p=0.03) but no significant differences between groups (). There were no significant within group changes in neutrophils in either group. However, over the entire study period there was a increase in mean neutrophils of 5.3% for the intervention group and a decrease in neutrophils of −6.7% for the control group; with a significant between group difference (p=0.04).
Intervention subjects reported significantly more changes in self-management behavior during the study than controls (mean per person changes 1.82 versus 0.87, p<0.0005). Overall, 98% of intervention subjects reported one or more changes vs. 64% of controls. Intervention subjects reported improving inhaler technique (p=0.03), reducing outdoor allergen exposure (p=0.02) and reducing indoor dust exposure (p<0.0005) significantly more frequently than controls as shown in .
Self-Described Changes in Self-Management Behavior after Study Participation