The purpose of this study was to estimate true treatment effect measured by clinicians using the Health of the Nation Outcome Scale for Children and Adolescent (HoNOSCA) corrected for regression to the mean (RTM), and for ceiling and floor effects. The present study was based on routine clinical data from a national database in which HoNOSCA is scored before and after therapy in order to show the treatment effect. We constructed a modified score to correct for the potential bias due to RTM, and used Generalized Linear Models analysis to adjust for the ceiling and floor effect. Our study showed that if these corrections are implemented in routine outcome measurement of children diagnosed with Hyperkinetic Disorder (HKD), the estimate of change in total HoNOSCA score after adjustment is clearly smaller in absolute value than the absolute difference estimate. If RTM and the ceiling/floor effect is ignored it will lead to misinterpretation of the results.
Psychiatry Research, 2012, Vol 200, Issue 2-3, p. 867-71