Implementation of Primary Psychological Healthcare Policy to Address the Risk of Depression in Underprivileged Children and Adolescents, in the Entire Lower‐Middle‐Economic‐Status City of China: An Observational, Multicenter, and Single‐Arm Cohort St

<b>Background:</b> Given the historically high incidence of depressive disorders among children/adolescents, efforts to implement universally accessible primary psychological health care policies have been undertaken globally. However, the practical implementation and its association with depression risk reduction remain uncertain, particularly for underprivileged children/adolescents who are underrepresented in the current system. <b>Methods:</b> A large-scale cohort of underprivileged children/adolescent population aged 6-18 was enrolled (<i>n</i> = 290,239). Subgroups with specific underprivileged conditions were identified, including de facto unattended children/adolescents (dfUCA), orphans, and children/adolescents facing especially difficult circumstances, "left-behind" and "single-parent" children/adolescents. A subgroup of matched typically developing individuals was also included. These subgroups underwent longitudinal assessments for the incidence of identifying depression on Oct 30, 2022 (baseline, before implementing primary psychological health care policy), May 21, 2023 (half year follow-up), and Oct 29, 2023 (1-year follow-up), respectively. <b>Results:</b> At baseline, nearly twice as high incidence of depression was found in the underprivileged group (13.9%, 95% confidence interval [CI]: 13.7-14.1) as in the control group (7.5%, 7.2-7.7). After the implementation of the primary psychological policy, at the half year follow-up, a notable decrease in the incidence of depression was observed in both the underprivileged group (5.8%, relative risk reduction (RRR) = 51.6%, 51.5-51.7, <i>p</i> < 0.001) and the typically developing group (4.0%, RRR = 34.5%, 27.9-41.0, <i>p</i> < 0.001), particularly among orphan girls aged 12-18. The observed changes in depression incidence across all underprivileged populations were statistically noninferior compared to the typically developing group (all <i>p</i> < 0.001). At the 1-year follow-up, the observed benefits were consistent across all subgroups when compared to baseline. The average expenditure per child/adolescent was $1.6 in implementing such a health care policy. <b>Conclusions:</b> Implementing the primary psychological health care policy is associated with a reduction in the citywide risk of depression among underprivileged children/adolescents in low-middle-income areas.