Of the initial mailing to 600 eligible pediatricians, 100 were returned unopened without a forwarding address and were replaced. The overall response rate was 50.5% (). We excluded 61 respondents (10.2%) who reported being retired or in specialty care practice and two respondents who completed the demographics portion of the questionnaire but did not complete the CCADDS. Non-respondents included 43 (7.2%) who returned declination cards and 254 (42.3%) who never responded. Respondents did not differ (p>0.05) from non-respondents with respect to gender, years in practice, or region of the country. Participation rates by region varied from 47.3% to 53.4%, but differences in these rates were not significant (p>0.05).
Demographic characteristics of respondents are shown in . Respondents were predominantly male, older than 45 years old, white, and practiced in suburban communities. There were few Hispanic or African-American respondents. They reported on average 16.6 (SD ± 9.6) years of practice experience and saw on average 103.2 (SD ± 52.7) patients a week. Their mean PBS subscale scores were 13.1 for beliefs and 15.8 for burden, which were similar to pediatricians who participated in the Child Behavior Study, a large nation-wide study of primary care clinicians (mean beliefs score 12.8, mean burden score 15.3).25
Demographic Characteristics of Respondents
The Scree plot generated from exploratory factor analysis suggested the presence of three or four factors. The addition of factors after the fourth resulted in a relatively horizontal downward sloping line. The 3- and 4-factor solutions were examined for plausibility. The 3-factor solution was selected, since it resulted in a plausible factor structure, in which items corresponded to beliefs, activities, and connectedness domains as in the IACS. The 4-factor solution was not deemed plausible.
Thirty-four percent of the total variance among items was explained by the 3-factor structure. The 3-factor solution was rotated orthogonally (Varimax) and obliquely (Promax). The oblique rotation generated a greater hyperplane count (59 vs. 33) and a simpler solution with absence of cross-loading items than the orthogonal rotation. We therefore selected the oblique solution and dropped the four items without salient loadings to obtain an overall scale with 37 items and 3 subscales (beliefs, activities, and connectedness). Items in the beliefs subscale reflect attitudes and beliefs regarding the importance of collaborating with schools and mental health agencies. Items in the activities subscale measure specific activities that involve collaboration, e.g. developing referral arrangements or coordinating treatment plans. Items in the connectedness subscale measure how well clinicians or practices collaborate with community organizations.
The rate of missing data was low (0.4%) with individual items having at most 3 missing responses out of 240 respondents (). Overall, only 15 subjects (6.3%) had any missing items. There were no differences between those with and without missing items with regards to age, race, sex, practice location, and years in practice (p>0.05). We therefore assumed that missing items were missing completely at random and did not impute missing values. There were no floor effects. The beliefs domain had the highest ceiling effect with 4% of respondents reporting the highest possible score. Ceiling effects for the other two subscales were low (0.4%).
CCADDS Items and Internal Consistency*
The internal consistency for all three subscales (α =0.80–0.89) and the overall scale (α =0.91) were good, suggesting that items within subscales generally were associated with each other. Corrected item-total correlations were in an appropriate range for all items (r >0.20). Selective removal of individual items did not improve the internal consistency of any subscales.
The CCADDS subscale scores were moderately correlated with each other. Correlation coefficients ranged from 0.31 for beliefs and connectedness to 0.51 for activities and connectedness, suggesting medium intercorrelations. The CCADDS total score and subscale scores had small to medium correlations with the PBS total and subscale scores in the expected direction with two exceptions (). The beliefs subscale of the CCADDS did not correlate significantly with the burden subscale of the PBS, and the activities subscale of the CCADDS did not correlate significantly with the beliefs subscale of the PBS. In general, the CCADDS total score correlated best with the PBS total score and with reported frequency of mental health consultation and receipt of referral information.
Correlations between Collaborative Care for ADD Scales (CCADDS) and Physician Belief Scales (PBS) and Frequency of Mental Health Activities.
Intercorrelations between CCADDS total and subscale scores and reported frequency of mental health activities were examined (). CCADDS total and subscale scores correlated best with reported frequency of mental health consultations (r =−0.17 to −0.42) and least with reported frequency of on-site mental health providers (r =−0.05 to −0.22). Only the connectedness subscale scores and the total scores correlated significantly with all mental health activities. The beliefs subscale scores consistently correlated worse with mental health activities.
Discriminant validity of the CCADDS total scores among subpopulations of the sample was examined. As hypothesized, CCADDS total scores were not significantly different by sex, age, or race-ethnicity. Although we had postulated differences in CCADDS scores by practice location, there were no significant differences after adjustment for multiple comparisons.