Medical Disorders and Complications of Alcohol and Other Drugs and Multiple Morbidities: An Introduction

Multimorbidity is characterised by distinct clustering of multiple concurrent health conditions. Multimorbidity is a growing concern worldwide particularly amongst certain ‘at-risk groups’, such as drug and alcohol users and/or individuals with mental health problems [1, 14]. Some clusters are particularly common and often share a mechanistic basis (concordant conditions). Mechanistically distinct (discordant) morbidities [7, 9] may sometimes be a secondary consequence of ill-health (e.g. depression), whereas adverse reactions to treatment may also underlie some common clusters. Importantly, some clusters show no obvious connection, hinting at currently unknown risk factors or causal linkages.