Abstract
Background:Multimorbidity is defined as the co-existence of two or more long-term health conditions within the same individual. While it is well established that Attention-Deficit Hyperactivity Disorder (ADHD) is associated with both mental and physical health comorbidities, certain factors suggest ADHD could elevate the risk of accumulating multiple conditions over time. ADHD symptoms may impair self-management of long- term health conditions, while diagnostic overshadowing, whereby ADHD symptoms are misattributed to co-occurring conditions, may result in fragmented healthcare. Despite this, the impact of ADHD on the development of multimorbidity in adulthood remains underexplored. General Practitioners (GPs) are arguably well placed to take on a greater role in adult ADHD management, considering their integrative biopsychosocial approach to care and routine management of multimorbidity.Aim:The aim of this systematic review and meta-analysis is to examine the association of ADHD with the development of multimorbidity in adulthood.Methods:This systematic review and meta-analysis, reported per PRISMA-P guidelines, will include observational studies (cohort, case-control, cross-sectional, and sibling comparison designs) examining multimorbidity risk in adults with ADHD compared with adults without ADHD. Multimorbidity is defined as the coexistence of two or more long- term health conditions (in addition to ADHD). MEDLINE, Embase, PsycINFO, and Web of Science Core Collection will be searched from inception, without language restriction, supplemented by citation searching and grey literature sources. Two reviewers will independently screen records and extract data, with disagreements resolved by discussion or third-reviewer arbitration. Risk of bias will be assessed using the Joanna Briggs Institute Critical Appraisal Tools. Where sufficient homogeneous data are available, random-effects meta-analyses will pool crude and adjusted effect estimates, with heterogeneity assessed using Chi2 and I2, and prespecified subgroup and sensitivity analyses will be conducted. Findings will be synthesised narratively where meta-analysis is not feasible.Discussion:This systematic review will provide a comprehensive synthesis of studies examining the association between ADHD and the development of multimorbidity in adults. With increasing recognition of the importance of a lifespan approach to ADHD management, this review will provide important information on the risk of multimorbidity and will support a holistic approach to clinical decision making for adults living with ADHD.