Table 1 Eligibility criteria for inclusion of studies in the review

Population

Include: Adults (≥18 years) without critical illness in the general population; hospitalized for any reason; or with critical illness (i.e., admitted to ICU).

Studies that include children will be considered if the population mean age – 1 standard deviation is ≥18 years.

Exclude: Children and adolescents and studies where the mean age – 1 standard deviation is <18 years.

Exposures

Include: Indigenous identity as the primary focus; within Indigenous populations, we will consider risk factors including age, sex/gender, presence of comorbidities, acuity of illness (e.g., APACHE II, SOFA), primary diagnosis (e.g., trauma, sepsis, surgery), setting, and others as reported by the included studies.

Exclude: Studies focused exclusively on non-Indigenous populations, studies with mixed populations where data specific to Indigenous Peoples cannot be isolated or the sample of the Indigenous population is less than 5% of the total study population; studies focused on a population with an identified condition and/or procedure, and where Indigenous identity is examined as a risk factor/covariate (i.e., Indigenous is not the primary focus)

Comparators

Include:

 - For incidence of ICU admission, studies require a comparator group with non-Indigenous identity (“general population” and “hospitalized”). We will include studies without a comparator group if they investigate risk factors for ICU admission within the Indigenous population.

 - For ICU-admitted populations, we will include studies with or without a non-Indigenous comparison group.

Exclude: Comparisons between different Indigenous groups.

Outcomes

Include: Incidence of critical care admission; associations between risk factors (age, sex, acuity), and critical care access; and critical care outcomes.

Primary:

 - ICU admission^a

 - ICU mortality

Secondary:

 - ICU length of stay, ICU re-admission, mechanical ventilation, duration of mechanical ventilation, tracheostomy, vasoactive support, duration of vasoactive support, acute dialysis, duration of acute dialysis, advanced life support, total hospital length of stay, hospital mortality, rehospitalization, quality of life measured on any scale

Study designs

Include: Prospective and retrospective cohort studies, case series with aggregate data from at least 100 participants, clinical trials (e.g., usual care or placebo arm), analytic findings from gray literature reports

Exclude: Evidence syntheses, descriptive and cross-sectional studies, case reports, and other reports that do not present any original data (e.g., commentaries, editorials, opinion pieces)

Settings

Any country

Time period

For mortality: in ICU, in hospital, 28 days, 1 year, >1 year

For rehospitalization: 0–6 months, 6–12 months, any longer length of follow-up

For quality of life: measured at any point in time

For other outcomes, any time point or length of follow-up is eligible.

Language

Include: English

Exclude: Any language other than English

Date of publication

Any