This is the first study to examine the predictive validity and clinical utility of the VARS performance items for predicting LDs. Our results show that the VARS performance items can be used reliably by physicians to determine which children do not need to be referred for evaluation of a comorbid reading or spelling LD. This is important clinical information, given the high rates of ADHD/LD comorbidity6
and the fact that community physicians are relied on to determine whether children with ADHD should be referred for psychoeducational testing. Furthermore, the capacity of schools and psychologists to complete psychoeducational testing is limited, and use of the VARS performance items should increase physicians’ ability to make appropriate referrals.
By using ROC analyses, optimal cutoff values for ruling in/out the presence of a LD were examined. None of the items had acceptable cPPPs for ruling in or confirming a LD. This is not overly problematic, because it is not the role of physicians to diagnose LDs. Furthermore, the VARS items have good clinical utility in identifying children who likely do not meet the criteria for a LD and therefore do not need to be referred for evaluation. In this study, the combination of parent and teacher ratings or teacher ratings alone provided the best clinical utility for ruling out comorbid LDs and the need for referral. As shown in , a cutoff point of 7.5 for the sum of the VARS parent and teacher reading items had excellent cNPP for ruling out both reading (cNPP = 1.0) and spelling (cNPP = 0.89) LDs. This means that, in this sample, children with parent plus teacher reading item scores of <8 were highly unlikely to meet the criteria for a comorbid reading or spelling LD.
Teacher ratings alone also could be used to rule out the presence of reading and spelling LDs. Specifically, a cutoff score of 4 for the VARS reading item rated by a teacher had excellent cNPP (cNPP = 0.80) for ruling out a reading LD, and a cutoff score of 4 for the VARS writing item had excellent cNPP (cNPP = 1.0) for ruling out a spelling LD. The cNPP of 1.0 for the writing item means that no child with a teacher-rated score of <4 for the VARS writing item met our criterion for a spelling LD. This cutoff point makes sense, given that a rating of 3 on the VARS indicates that the child’s ability in the area is in the average range and scores of 2 and 1 indicate above-average ability.
Only 1 parent-rated item had adequate clinical utility. A cutoff score of 4 for the VARS reading item rated by the parent met the NPP criterion for ruling out a reading LD (cNPP = 0.69). The greater utility of teacher ratings is not surprising, given that teachers observe children’s academic skills directly on a daily basis and in comparison with those of other children. Furthermore, teachers often are aware of children’s reading, writing, and math proficiency on the basis of their scores on school-administered standardized tests. This finding highlights the importance of physicians collecting VARS ratings from the school, as recommended by the AAP guidelines.3
None of the parent- or teacher-rated items met the criterion for ruling in or out a math LD. Physicians need to use the VARS items in combination with assessment of math functioning at school to determine whether a referral is needed. It is important to note that none of the VARS items should be used alone to determine whether to refer and therefore interviewing further about math abilities is not an added burden. Specifically, referral decisions always should be made on the basis of the combination of data from the VARS items, interviews about school functioning, and examination of school records, such as achievement test scores.
In cases in which it is unclear whether a referral is needed, physicians should initiate treatment for ADHD and monitor the VARS academic impairment items for improvement. Children with academic difficulties primarily attributable to ADHD (eg, difficulties focusing in class) should benefit from ADHD treatment and VARS academic impairment ratings should improve. However, academic problems attributable to a comorbid LD are basic skill deficits (eg, reading, math, and writing skills) and are unlikely to normalize with ADHD treatment.19,20
If symptoms of ADHD improve with treatment but the VARS academic performance ratings do not improve, then referral for psychoeducational evaluation may be warranted.
We classified cases as LDs on the basis of the results of abbreviated achievement assessments, and children in the sample did not receive full psychoeducational evaluations. Therefore, some cases might have been classified incorrectly as LDs, which might have affected the results of the clinical utility analyses. Additional research is needed to replicate these results by using full psychoeducational evaluations to diagnosis LDs. In addition, all of the participants in this study were stimulant naive, and our findings may not be generalizable to groups of children already being treated for ADHD. Future research is needed to determine whether the VARS can be used to rule out LDs among children with diagnosed ADHD who are receiving treatment. Finally, it is important to note that children with above-average cognitive abilities may not exhibit academic problems according to VARS ratings during early childhood. Physicians need to screen consistently for academic problems, to determine whether LD evaluation referral becomes necessary as children progress through school.
WHAT’S KNOWN ON THIS SUBJECT
Approximately 30% of children with ADHD also meet the criteria for a comorbid learning disorder. Determining when to refer children for LD evaluations can be difficult, and data-driven approaches are needed to facilitate these decisions.
WHAT THIS STUDY ADDS
The authors evaluate the utility of the Vanderbilt ADHD Rating Scale performance items for identifying children with ADHD who are unlikely to meet the criteria for a LD. The authors use these data to make recommendations about when children should be referred.