Anxiety and depression are common and associated with higher use of general healthcare services. The aims of this systematic review were to (1) estimate the prevalence of anxiety and depression in adults who are high or costly users of general healthcare services in comparison to routine users and (2) estimate the magnitude of healthcare costs associated with the presence of anxiety and depression.

Systematic review of the available literature.

MEDLINE, PsycINFO, EMBASE, CINAHL, PROSPERO and Cochrane Library were systematically searched without language restriction from inception to 1 April 2019 and updated on 25 October 2022, 16 October 2024 and 18 February 2026.

Eligible studies described adults aged ≥18 years who were defined as high or costly general healthcare users and where the prevalence and/or associated costs of anxiety and/or depression were quantified.

Three reviewers independently extracted information on study characteristics, exposure and outcomes.

From the 38 412 identified articles, 27 studies from 10 countries (in Europe, North America and Asia) involving 6 145 907 participants met eligibility criteria and were included. There were wide variations in the estimated prevalence of anxiety (3.8–67.2%) and depression (4.7–77.9%) among high healthcare users. The prevalence of both disorders was higher among high healthcare users than routine users in all studies with non-high user comparator groups. Only four studies investigated healthcare costs associated with depression. These uniformly reported that general healthcare costs are higher for those with depression than those without. No studies investigated costs associated with anxiety.

Anxiety and depression are over-represented among high or costly healthcare users, although accurate quantification of the magnitude of difference is precluded by significant methodological heterogeneity and variability in definitions used. Improved identification of covert mental health problems is essential for the provision of effective interventions for patients and healthcare expenditure reduction. Future research should prioritise a standardised approach, with agreed definitions for high and/or costly healthcare use in different contexts.

CRD42018102628.

Self-harm represents a significant public health concern and is a common reason for contact with urgent and emergency care (UEC) services among young people. Although young people frequently interact with multiple components of the urgent care system following self-harm, there is limited system-level evidence describing patterns of service use, transitions between services and repeat emergency department (ED) attendance. An improved understanding of how young people use UEC services after self-harm is needed to inform the design of more effective and appropriate care pathways.

This protocol describes a prospective cohort study using an extract from the Centre for URgent and Emergency care research database (CUREd+) research database, which comprises routinely collected, linked healthcare data from the National Health Service 111 (NHS 111), ambulance services, urgent care centres, walk-in centres and EDs across Yorkshire and the Humber, England. The study population will include young people aged ≤25 years presenting to UEC services between April 2019 and March 2022 with self-harm coded as the reason for attendance. Analyses will describe the prevalence of self-harm presentations across UEC settings, quantify the proportion of NHS 111 and ambulance contacts resulting in ED attendance within 24 hours and examine factors associated with ED reattendance at 3 and 12 months. Mixed-effects logistic regression models will be used to account for repeated attendances, confounding variables and temporal variation, including changes related to the COVID-19 pandemic. Anticipated analysis period: January 2026–January 2027.

Ethical approval has been granted by the University of Leeds (MREC 22-079 Amd1) and the University of Sheffield (Ref 068194). The CUREd+ research database operates under Research Ethics Committee approval (23/YH/0079) and Confidentiality Advisory Group approval (18/CAG/0126). Individual consent is not required as all data are pseudonymised at source. Findings will be disseminated through peer-reviewed publications, conference presentations and public-facing outputs coproduced with patient and public involvement groups.