This is the first study to examine the persistence of depressive symptoms after a positive screening test in a primary care sample of youth. A key finding of this study is that ~50% of youth who screen positive for depression do not continue to screen positive 6 weeks later. This is consistent with the high placebo response rate in this age group6–8
and emphasizes the importance of developing strategies to identify which youth need active treatment versus “watchful waiting” (active monitoring and support from the primary care provider).
Depressive symptom severity has been found to be a significant predictor of depression persistence in pediatric specialty settings.18,19
We found a similar pattern in youth in our primary care population: each 1-point increase in the PHQ-9 above a score of 11 was associated with a 16% increased odds of continuing to be depressed 6 months later. When we examined severity categories based on the baseline PHQ-9 score, we also found that risk of persistence increased as severity increased. At 6 months, 2.5% of youth with mild symptoms at baseline were depressed compared with 28.1% of youth with moderate symptoms, 37.5% of youth with moderately severe symptoms, and 71.4% of youth with severe symptoms. These results suggest that the baseline depression symptom score is a strong predictor of depression persistence and that providers should consider initial severity of depressive symptoms when making a decision to recommend active treatment versus watchful waiting.
To decrease the likelihood of recruiting youth with transient symptoms for research studies, investigators commonly use a 2-stage screening protocol with a repeat depression screen at a specified time interval after baseline.6,28,29
In our study, we used a 6-week reassessment to evaluate the benefit of a 2-screen strategy to identify youth at highest risk for persistent depression. Among those who screened positive at baseline, we found that youth who also screened positive at 6 weeks had 2.9-times increased odds for continuing to be depressed at 6 months. This suggests that in cases in which the need for treatment is not clear, providers might consider watchful waiting with a repeat screen at 4 to 6 weeks. Youth who have persistent symptoms at 4 to 6 weeks should then be assisted with starting active treatment.
In regression analyses, the results at 6 weeks were a stronger predictor of persistence than baseline PHQ-9 score. Despite this finding, we would not recommend watchful waiting and a 2-stage screening procedure for all youth. Youth who are clearly at high risk for persistence (eg, those with a PHQ-9 ≥20) as well as those who have a high risk for harm with delay of treatment (eg, youth with suicidal ideation or high degrees of functional impairment) should be assisted in seeking treatment as soon as depression is detected.
Other predictors of persistence that have been identified in at least 1 study of depressed adolescents in mental health specialty settings include female gender,18
and poor support from peers20
In our study, each of these variables was associated with the presence of a positive depression screen at baseline, but none were associated with depression persistence. There are many possible reasons for this absence of association with persistence in our study. First, because most of these predictors were found to be associated in only a single previous study and some predictors, such as female gender,17,18,20
have had conflicting results, there may be no true association between these variables and persistence. Second, diagnosed youth in specialty settings may have greater severity of comorbid disorders, more social stress, and longer history of depressive symptoms than screen-positive youth in primary care. The absence of association may be due to these underlying differences in frequency and severity of these characteristics in the study population. Finally, because we were interested in measures that could practically be used within the time constraints of a busy primary care practice, our study used brief symptom screens to assess for comorbidity and family and peer support, whereas previous studies have used more detailed peer and family support measures and structured clinical interviews.17,20
The decreased specificity in our measures may have resulted in misclassification, and this may have weakened our potential to identify an association. Regardless of the reason, although we encourage providers to assess for comorbidity to help inform appropriate treatment of patients, our findings suggest that these measures are not as helpful as severity of depression in determining which youth will have persistent symptoms.
This study was conducted in an insured, predominantly white population in the Pacific Northwest and may not be generalizable to all settings. Additionally, assessments were conducted at discrete points in time and relied on the PHQ-9, which refers only to symptoms in the previous 2 weeks. It is possible that there may be misclassification of persistence in both directions (ie, patients could have been asymptomatic between episodes but have had a recurrence in the 2 weeks before evaluation, or patients could have been symptomatic in the interval but not in the 2 weeks before evaluation). We did not measure quality or adequacy of depression treatment, making it difficult to draw conclusions regarding the impact of treatment on persistence. In observational studies, treatment is confounded by severity of illness: youth with greater severity are more likely to receive treatment but are no more likely to have improvement (this is because severity is the best predictor of outcome and, in usual care, few youth actually get guideline-level treatment).30–32
Finally, although baseline participation and follow-up rates were high, our screening response rate of 60% may have introduced some response bias.
Despite these limitations, this study has important clinical implications. As we follow the US Preventive Services Task Force’s recommendation and institute broad-based screening of adolescents in primary care settings, we are likely to encounter more youth who have short episodes of depression that resolve with monitoring and support. Given limited resources and potential risks for harm, providers need guidance regarding which youth are most likely to benefit from evidence-based active treatments versus watchful waiting in the primary care setting. The results of our study suggest that youth with higher severity of depressive symptoms at presentation and youth who continue to meet criteria for depression at a 6-week reassessment are at high risk for long-term persistence and would benefit from early institution of evidence-based treatments.