Evidence-based assessment of pediatric bipolar disorder, part II: Incorporating information from behavior checklists

The previous commentary described how to gather and use information about the base rate of pediatric bipolar disorder (PBD) and the family history of bipolar illness to assess the risk of PBD for an individual case, using an evidence-based practice (EBP) framework. This month’s column continues with that case and demonstrates how behavior rating scales or checklists are another inexpensive and potentially useful source of information. This column shows how to make use of likelihood ratios (how much more likely a disorder is to be present than absent for a given test score in a defined population [Guyatt and Rennie, 2002]) to assess the likelihood of PBD in an individual case. Likelihood ratios are valuable because they may enable a clinician to take a legitimate shortcut and use an easier to administer diagnostic test (here the Child Behavior Checklist [CBCL]) in place of a more time-consuming but definitive test (here the Schedule for Affective Disorders and Schizophrenia for School-Age Children [Kaufman et al., 1997]). The specific details of the case have been changed so that the person described is not recognizable. At the time of intake, the biological mother completed the CBCL (Achenbach, 1991; Achenbach and Rescorla, 2001). Is CBCL information helpful in assessing for PBD? In Medline, the search terms ‘‘CBCL AND bipolar disorder’’ generate multiple hits, including a meta-analysis of previous studies comparing CBCL scores for cases diagnosed with PBD compared with other children (Mick et al., 2003), along with some more recent studies (Kahana et al., 2003; Youngstrom et al., 2004). The meta-analysis presents mean CBCL clinical syndrome scale T scores in clinical bipolar youth, with the Aggressive Behavior scale being most elevated, followed by Anxious/Depressed, Attention Problems, and Delinquent Behavior. Mick et al. (2003) propose these scales as a potential ‘‘bipolar profile’’ but do not suggest optimal cutoff scores to differentiate PBD. The more recent articles compared the CBCL subscales with the Externalizing problems broad band score (a composite of several syndrome scales) and found that after controlling for the Externalizing score, none of the other CBCL scales improved the identification rate of PBD (Kahana et al., 2003; Youngstrom et al., 2004). It is worth noting that all published research on PBD to date has used older versions of the CBCL. The current version in clinical use is the 2001 form, which changed some items and reorganized some scales. However, the Externalizing scale score correlates 0.99 between the 1991 and 2001 versions (Achenbach and Rescorla, 2001), suggesting that performance should be similar. Overall, based on these findings, it makes sense to focus on the Externalizing score. Consider, therefore, the likelihood ratios associated with low, intermediate, high, and very high Externalizing CBCL scores, broken down separately by age (Youngstrom et al., 2004). This approach examines the performance of multiple segments of the test scores rather than simply dividing the test at one place (as is done when calculating the sensitivity and specificity of the test at a single threshold score) (Guyatt and Rennie, Accepted February 11, 2005. From the Departments of Psychology and Psychiatry, Case Western Reserve University/University Hospitals of Cleveland. This research was supported by NIMH R01 MH-066647 as well as NIMH P20 MH 066054 and a Clinical Research Center Grant from the Stanley Medical Research Institute. Thanks also to John Hamilton, M.D., and Martha Hellander, J.D., for suggestions and comments. Reprint requests to Dr. Eric A. Youngstrom, Department of Psychology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 441067123; e-mail: Eric.Youngstrom@case.edu. 0890-8567/05/4408–0823 2005 by the American Academy of Child and Adolescent Psychiatry. DOI: 10.1097/01.chi.0000164589.10200.a4