Comparison of indices of clinically meaningful change in child and adolescent mental health services: difference scores, reliable change, crossing clinical thresholds and 'added value' - an exploration using parent rated scores on the SDQ.

BACKGROUND

Establishing what constitutes clinically significant change is important both for reviewing the function of services and for reflecting on individual clinical practice. A range of methods for assessing change exist, but it remains unclear which are best to use and under which circumstances.

METHOD

This paper reviews four indices of change [difference scores (DS), crossing clinical threshold (CCT), reliable change index (RCI) and added value scores (AVS)] drawing on outcome data for 9764 young people from child and adolescent mental health services across England.

RESULTS

Looking at DS, the t-test for time one to time two scores indicated a significant difference between baseline and follow up scores, with a standardised effect size of d = 0.40. AVS analysis resulted in a smaller effect size of 0.12. Analysis of those crossing the clinical threshold showed 21.2% of cases were classified as recovered, while 5.5% were classified as deteriorated. RCI identified 16.5% of cases as showing reliable improvement and 2.3% of cases as showing reliable deterioration. Across RCI and CCT 80.5% of the pairings were exact (i.e., identified in the same category using each method).

CONCLUSIONS

Findings indicate that the level of agreement across approaches is at least moderate; however, the estimated extent of change varied to some extent based on the index used. Each index may be appropriate for different contexts: CCT and RCI may be best suited to use for individual case review; whereas DS and AVS may be more appropriate for case-mix adjusted national reporting.