Among the 207 cases assessed at follow-up, no data were missing in four of the six outcome domains. Three girls with ADHD were missing WIAT scores and we did not substitute values for these missing data. Because teacher report on the Dishion Social Acceptance Scale was available for only 152 of the 207 (73%) cases, for 55 cases we imputed a negative social preference score using parent-reported CD/ODD symptoms. The association between externalizing symptoms and peer rejection is widely-acknowledged, and externalizing problems may be causally related to peer rejection in childhood (Pedersen, Vitaro, Barker, & Borge, 2007
; Schwartz, McFadyen-Ketchum, Dodge, Pettit, & Bates, 1999
), although the causal pathway between these variables is likely bidirectional. Furthermore, parent-reported CD/ODD symptoms was the only variable tested in a stepwise regression that predicted significant variance in negative social preference scores among the 152 cases with valid Dishion scale data (R2
= .18). In order to check the validity of our data imputation strategy, we computed results among only those cases with teacher-reported peer data, and they were virtually identical to those we present below which include cases with imputed data. Furthermore, as explained above, analyses addressing whether teacher data were missing at random suggest that substituting missing teacher data in order to employ the complete follow-up sample in our analyses did not compromise the generalizibility of findings, and may have enhanced it.1
Thus, our final n for within-domain analyses (except for school achievement) was 207 and our final n for across-domain analyses was 204.
After establishing thresholds for PA on each measure, as described above, we counted the number of girls whose scores surpassed the individual domain-level thresholds for PA, with results presented in . Among girls with childhood ADHD, a minority (19.8%) was essentially free of ADHD symptoms by adolescence, compared to 86.4% of the comparison girls. Fewer than half of the ADHD sample were below our threshold for externalizing problems (42.1%) or internalizing problems (49.2%), compared to 91.3% and 85.2% of the comparison girls, respectively. Similarly, 40.5% of the ADHD girls demonstrated adequate social skills during adolescence, whereas more than twice as many (82.7%) of the comparison girls did. Over half of the girls with childhood ADHD (61.1%) received adequate teacher-reported social preference ratings, whereas 87.7% of the comparison girls did. Sixty-five percent of the girls with childhood ADHD were achieving adequately in math and reading during adolescence, compared to 96.3% of the comparison girls. In each of the outcome domains, the rate of PA among ADHD girls was notably lower than the rate of PA among comparison girls (all ps < .001). Effect sizes in each individual domain indicate that for girls with childhood ADHD the odds of maladjustment (failing to show PA) during adolescence were between 4 and 25 times greater than the odds of maladjustment among comparison girls.
Information in addresses our primary question of overall
rates of across-domain PA, by which we mean that a given participant was free of significant symptomatology and functional impairment in most domains. Overall PA was operationalized as meeting criteria for PA in at least five of the six domains. Our rationale was two-fold: First, it seemed sensible that competence in most domains, but not necessarily every single one, would be required for an adolescent to be considered well-adjusted overall;
and second, we wished to be consistent with the procedures of Lee et al. (2008)
in which they defined well-adjusted overall as surpassing thresholds for minimum competence in at least all but one domain. Similar to Lee et al. (2008)
, we found a very large association (t202
= 12.47, p
< .001, d
= 1.7) between overall impairment (in our case, measured using the Columbia Impairment Scale) and meeting PA criteria in four or fewer domains versus at least five of the six domains.
Frequency counts of girls meeting positive adjustment criteria during adolescence in up to six domains
Only 16.4% of the girls with childhood ADHD were positively adjusted during adolescence, utilizing this criterion, compared to 86.4% of the comparison girls. This difference was highly significant (X21,204 = 97.51, p < .001), with an odds ratio of 32.7 (95% CI = 14.8 to 72.6). Thus, for girls with childhood ADHD, the odds of failing to meet overall PA criteria were 32 times greater than the odds for comparison girls. Of the 20 girls with childhood ADHD who did meet criteria for overall PA, five surpassed PA criteria in all six domains. Of the 15 remaining, the number failing to meet PA criteria in each domain was as follows: five in the ADHD domain, one in the externalizing domain, four in the internalizing domain, one each in the social skills and peer acceptance domains, and three in the school achievement domain.
We then examined overall PA in the domains other than ADHD symptoms, defined as meeting PA criteria in four of the five remaining domains. As expected, more girls with childhood ADHD demonstrated PA with this more lenient criterion, but the difference between this percentage (28.5%) and that for the comparison girls (87.7%) was still highly significant (X21,204 = 68.57, p < .001), with an odds ratio of 17.9 (95% CI = 8.3 to 38.5).
Post hoc, when we operationalized PA using a subset of domains reflecting impairment only (the social skills, peer acceptance, school achievement domains), the percentages meeting PA criteria in all three of these domains, 22.2% in the ADHD group and 81.5% in the comparison group (X21,204 = 69.77, p < .001; odds ratio = 15.6, 95% CI = 7.7 to 31.7), were similar to the primary results reported above. Thus, independent of core and comorbid psychiatric symptoms, during adolescence the majority of girls with childhood ADHD were notably more impaired than comparison girls in terms of social and academic functioning.
No differences existed in rates of PA among girls with ADHD when cohort differences (i.e., year of ascertainment: 1997 versus 1998 versus 1999) were examined (X21,123= .53, p = .766; odds ratio = 1.2, 95% CI = .7 to 2.2). The association between childhood ADHD type (inattentive versus combined) and overall PA was marginally significant (X21,123= 3.08, p = .079; odds ratio = .3, 95% CI = 0.1 to 1.2), with 7.7% of girls with inattentive-type ADHD during childhood showing PA during adolescence, versus 20.2% of girls with combined-type ADHD. Regarding treatment status among girls with ADHD, use of educational intervention services at school since baseline was not related to PA. However, having received psychotropic medication in the year prior to the follow-up visit (X21, 119 = 3.73, p = .053; odds ratio = 2.6, 95% CI = 1.0 to 7.2) and having received psychological services outside of school since baseline (X21,119 = 20.21, p < .001; odds ratio = 9.9, 95% CI = 3.2 to 30.6) were negatively associated with rates of PA. In other words, among girls with childhood diagnoses of ADHD, use of psychological treatments (but not educational services) and medication treatments (to a marginally-significant degree) predicted lower rates of overall PA at follow-up.
We assessed change over time in PA status using an overall adjustment measure disregarding the ADHD domain, because at baseline, by definition, all girls with ADHD did not meet positive adjustment criteria in that domain and all comparison girls did. Consequently, we used baseline data to create an overall adjustment measure reflecting functioning in five domains (externalizing symptoms, internalizing symptoms, peer acceptance, social skills, and school achievement), which was highly comparable to the analogous measure we employed at follow-up. Specifically, we defined thresholds for PA at baseline within each domain using the average of the ADHD and comparison group means. We then examined change over time in across-domain PA (disregarding ADHD status) as a function of baseline diagnostic group. At baseline, only 17.1% of the ADHD girls met PA criteria in four of five domains compared to 82.9% of the comparison girls. By adolescence, these figures were 28.5% and 87.7%, respectively. The baseline to follow-up change in PA frequency among comparison girls was not significant, but the change for girls with ADHD (17.1% vs. 28.5%) was significant (X21, 123 = 10.24, p = .001; odds ratio = 0.2, 95% CI = 0.1 to 0.6). This finding suggests that girls with ADHD were more likely to show improvement over time, in terms of moving to the positively adjusted category, than were comparison girls. However, despite this relative improvement, their rate of PA at follow-up (28.5%) was still far lower than the rate for comparison girls (87.7%).