Our findings suggest that primary care depressed youths aged 13–21 who receive treatment that meets at least minimum criteria for appropriate care for depression given current guidelines, compared with those who do not, have a significantly reduced likelihood of severe depression, falling from 45.2% for those without appropriate treatment, to 10.9% with appropriate treatment broadly. Results were consistent using our primary indicator of “appropriate treatment” (at least 6 specialty counseling visits or antidepressant medication in 6 months) and with alternative definitions (daily medication use for 2 or more months with application of minimum dosage criteria; the minimum number of psychotherapy visits specified as 4 or 12; a broad “upper bound” indicator of treatment defined as any counseling, antidepressant medication, or mental health specialty visit). What is unique about the context for these findings is that patients and providers made their own decisions about treatments and other than paying practices for care managers' time in the QI condition, the study did not pay for services, thereby preserving aspects of “usual” practice conditions for treatment provision. These results apply to all patients across intervention conditions, as this is a secondary, observational analysis of outcomes of exposure to appropriate care using data from all subjects in the randomized QI trial. The IV analyses offer a form of “as-treated” analysis in which across intervention conditions patients receiving broadly-defined “appropriate” depression treatment are compared with those who have not received “appropriate” treatment, with adjustment for potential unmeasured selection effects that can lead to sicker patients having more treatments but worse outcomes.
In this study, most youths receiving appropriate treatment had more than the minimum care required to meet criteria for the indicator. Most youths on antidepressants used them daily for 6 months, and the median number of counseling sessions among those with 6 or more was 15, which is similar to the number of sessions for a course of evidence-based psychotherapy such as CBT. Further, most youths using antidepressants also received counseling (71%), thus indicating combined treatment. The treatment-outcome relationships we estimated were due to this full range of treatments received among those meeting at least minimum criteria for appropriate care. Analyses using data only on counseling to define appropriate care and ignoring information on use/nonuse of medications yielded non-significant effects for youths with depressive disorders. This exploratory finding underscores the importance of including medication to define appropriate treatment for more severely depressed youths and indirectly suggests that medication use is a part of what makes “appropriate care” effective for this group. We used lower standards for acceptable treatment than are typical for defining guideline-concordant care, because we did not observe care in adjacent periods and did not have full histories of care, and in this circumstance, it is common to give the provider the benefit of the doubt in such effectiveness analyses. With an IV analysis approach, we could only specify as many treatment effects as there were instruments (i.e., one), so we could not separate the effects of medications and therapy, specify interactions, or determine how much care is necessary to improve outcomes. Indeed, the very broad indicator of access to any treatment or specialty consultation revealed similar results, thus suggesting that research is needed on how much of the value in effective care for primary care depressed youth, where treatment rates are low, can be attributed to use of evidence-based treatments, access to any treatment, or access to specialty consultation. This study can raise but not resolve this issue.
These findings are an important complement to the main experimental findings from YPIC (Asarnow et al. 2005
), which showed that a QI intervention had a modest effect on increasing both treatment rates (particularly psychotherapy/counseling) and clinical outcomes. The new observational IV analyses showing that receiving “appropriate treatment” substantially improves outcomes reinforce the importance of implementing interventions in primary care to increase rates of appropriate care as well as of further improving the effectiveness of QI interventions in doing so.
We note that the relatively modest improvements in treatment rates and clinical outcomes previously reported in the YPIC main experimental analyses (Campo and Bridge 2009
) are typical of QI interventions that encourage but do not assign treatments in a policy environment which does not strongly encourage the use of such programs. However, such programs are likely to be of increased importance in an era of implementation of parity and health reform legislation focusing on greater integration and quality of care (Barry and Huskamp 2011
). Our findings suggest that it did not take the rigorous implementation conditions of clinical trials for clinicians to provide and patients to receive treatments that substantially improved their outcomes including Latino youths, an important group for expanded coverage under health reform legislation.
The sample included patients with depressive disorder and patients with symptoms but without past-year disorder. We found a strong effect of appropriate treatment on outcome within each group. Thus, our findings may reflect a combination of treatment response among those with current disorder, early intervention among those with a previous disorder, and prevention of disorder among those with symptoms but no disorder history. For example, there is evidence that CBT is effective in preventing depressive disorder in high-risk youths (Clarke et al. 1995
; Garber et al. 2009
). Development of treatment approaches that encompass these diverse goals through an integrated practice strategy is an important issue for further research.
This study has important limitations. We had moderate response rates at enrollment, which somewhat limits generalizability—our findings may be more applicable to youths and families willing to address depression. Our study was limited to particular sites, and we did not have the sample to estimate site differences.
In YPIC, clinicians in both intervention arms had education in evidence-based practice. Although this feature likely shifted rates of appropriate care upward somewhat overall across both intervention arms relative to similar practices, we do not think that it shifted the effectiveness of appropriate care when provided, thus making the estimates provided here of potentially broad interest. This is especially the case because the analysis used data on depressed youth in both conditions, many youths did not receive appropriate treatment under each condition, the appropriate treatment indicator was applied across conditions, there was no CBT training in UC, and the medication criterion would be applicable across any practice setting.
Other limitations of the IV analysis approach arise if assumptions underlying the method may plausibly not hold, such as the instrument not being a strong predictor of treatment, thus resulting in under-estimation of CI for estimated treatment-outcome relationships; or when the instrument is not plausibly random with regard to outcome or the treatment indicator does not capture the instrument's effects on outcomes, thus leading to bias (Imbens and Rubin 1997
; Imbens and Rubin 2005
; Rosenbaum 2010
). The randomization of the intervention condition in YPIC supports its independence with regard to influencing outcome except through treatment effects. We included sensitivity analyses with a very broad definition of access to treatment or evaluation to increase confidence that treatment effects due to the intervention had been captured. There is reasonable support for instrument strength in that intervention status significantly predicts both the appropriate treatment and access to treatment/evaluation indicators in bivariate-probit analyses (see and in Appendix); and for the access indicator intervention differences that are significant in unadjusted bivariate analyses (chi-square (1)=6.25, p
Our indicators of appropriate treatment are broad and approximate meeting at least minimal standards for acceptable care rather than identifying what the best care strategies might accomplish. However, this study illustrates that even when selection effects obscure treatment-outcome relationships, then econometric techniques can reveal a positive effect of appropriate treatment on outcomes for diverse, depressed primary care youth. This is an important clinical and methods contribution to treatment effectiveness research concerning adolescent depression.