Inclusion and exclusion criteria
| Inclusion | Exclusion | |
|---|---|---|
| Population | Participants from the general population and assessed for the presence of multiple chronic conditions (multimorbidity). | Participants initially selected based on the presence of index diseases (ie, studies of comorbidity). Participants from solely institutionalised care settings (eg, nursing homes). Participants solely young people (age <18 years). |
| Exposure | Study exposure(s) included at least one household or area-level SDoH that aligns with factors from the World Health Organisation (WHO) Commission on SDoH (CSDH) Framework9 and the idea that SDoH are ‘causes of the causes’ of ill-health20 (eg, household income or area-level deprivation). | Study exposure(s) include individual SDoH only (eg, ethnicity). Study exposure(s) are direct “causes” of ill-health, such as health behaviours (eg, smoking), or are factors associated with the health system itself (eg, access to services). |
| Comparator | Study reports comparator group(s) for SDoH exposure(s) (eg, what is the prevalence of multimorbidity for those in the lowest vs the highest household income groups). | Study does not report a comparator group for SDoH exposure(s). |
| Outcome | Assess multimorbidity burden (prevalence or incidence studies). | Assignment to multimorbidity patterns or trajectories. Measures of multimorbidity severity (eg, indices used weighted by disease severity). |
| Study design | Peer-reviewed studies of quantitative research designs (cross-sectional and longitudinal). | Systematic reviews, meta-analyses and qualitative research (citations of relevant reviews searched). |