Matching needs to services: Development of a service needs index for determining care pathways in youth mental health.

Objective: To develop a Service Needs Index that measures a young person's needs across domains relevant to care provision and to examine the index's construction under different assumptions.

Methods: A cohort of young people ( = 2193) aged 12-25 years who sought help at youth mental health services across Australia were invited to use a digital platform (Innowell) as part of their care and complete a multidimensional assessment. Using online assessment data from the eligible 1611 individuals (73.5%), a Service Needs Index comprising three sub-indices (Clinical, Psychosocial, and Comorbidity) was constructed under two weighting approaches, an equal weighted scheme and a weighting scheme constructed with expert input and correlation-optimisation. These approaches were examined and compared.

Results: The Clinical, Psychosocial, and Comorbidity Indices were derived using standardised questionnaires to assess mental health symptoms and history, work and social functioning, and physical health and substance use, respectively. The expert input weighting scheme was favoured with less output uncertainty. Among those with the top 25% of Clinical Index scores, almost half also belonged in the group with the top 25% of Psychosocial Index scores, while 11.9% of the total sample were in the bottom 25% percentiles for both Clinical and Psychosocial Index scores.

Conclusion: These indices should be assessed in real-world settings before recommendations are made about their feasibility and acceptability; however, the indices could differentiate between needs to guide individual-level decision-making about service pathways for young people. Furthermore, population-level analyses of these aggregated indices can inform strategic decisions related to service planning and design.