Epidemiology of psychiatric disorders and self-harm in children and adolescents in the United Kingdom

Abstract

Abstract Aims. The three studies described in this thesis utilised two UK primary care datasets: The Clinical Practice Research Datalink (CPRD) GOLD and Aurum. Each study, or phase, addressed a specific but related research question, in which psychiatric disorders in young people was the common element. Because the existing evidence base was outdated and because there were signs that an increasing number of young people may be affected by poor mental health, phase 1 was concerned with estimating the incidence of common psychiatric disorders in young people. Psychiatric disorders are also known to be a strong risk factor for self-harm and suicide in adults, and for self-harm in adolescence, but they have not been examined comprehensively as risk factor for suicide in young people. In phase 2, therefore, I examined the association between psychiatric disorders and patterns of primary care service use and the risks for non-fatal self-harm and suicide concurrently among adolescents. Finally, in the absence of treatment guidance, I examined in phase 3 what treatment young people with anxiety disorders received in the year following diagnosis. Methods. Datasets for each study were created separately using CPRD GOLD and Aurum, and then merged and analysed as a single dataset. Phase 1. I delineated a cohort and estimated annual incidence rates for anxiety disorders, autism, attention-deficit hyperactivity disorder (ADHD), depression, eating disorders, and self-harm at 1-19 years of age for the period 2003-2018. Phase 2. I created two nested case-control studies with linked hospital and mortality records. Cases were adolescents aged 10-19 years old who between 1st January 2003 and 31st December 2018 had died from suicide (N=324) or experienced their first self-harm episode (N=56,008). Each case was matched on sex, age, and practice-level deprivation quintile with up to 25 control patients. By fitting conditional logistic regression, I examined how risks varied according to psychiatric diagnoses, prescribed psychotropic medication, patterns of primary care contact, and deprivation levels. Phase 3. I created a cohort of individuals with anxiety disorders aged 10-18. I then examined the annual prevalence of antidepressant and anxiolytic prescribing and referrals to mental health services in the year following diagnosis between 2003-2019 with a Poisson model, adjusting for age, sex, and practice-level deprivation. Results. Phase 1. Incidence rates for anxiety disorders, depression, autism, ADHD, and self-harm increased substantially among both boys and girls, 2003-2018. Rates for eating disorders also increased, but less sharply. Phase 2. Suicides occurred more often among boys (66%), but self-harm was more common in girls (68%). Only one third of cases had a psychiatric diagnosis recorded. Depression was most strongly associated with both self-harm and suicide risks (self-harm: Odds Ratio (OR) 7.9; 95% CI 7.8-8.2; suicide: OR 7.4; 95% CI 5.5-9.9). Except for autism, which was not associated with elevated suicide risk, all other psychiatric disorders were linked with similar risk elevations for self-harm as for suicide. Whilst self-harm risk rose incrementally with increasing levels of area-level deprivation, suicide risks did not. Phase 3. 34,468 out of 52,358 (66%) individuals were not prescribed a drug or referred to mental health services in the year following diagnosis. Those registered to practices in the most deprived compared to the least deprived areas were less likely to be referred (Prevalence Ratio (PR) 0.8, 95% CI 0.7-0.8) and prescribed antidepressants (PR 0.8, 95% CI 0.8-0.8). Antidepressant prescribing decreased substantially between 2003-2005 (18-11%) and then increased slightly between 2006-2019 (11-13%). Discussion. The phase 1 results suggest that an increasing number of young people might be seeking help for psychological distress. Changes to diagnostic criteria, reduced stigma, and increased awareness may partly expla

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Navneet Kapur (Supervisor), Roger Webb (Supervisor), Darren Ashcroft (Supervisor) & Matthew Carr (Supervisor)