Table 1 Study selection criteria

P

Adult patients presenting to the ED following initial triage.

I

Early warning systems or TTS, relying on periodic observation of selected, routinely recorded, physiological parameters, to promptly recognise deteriorating patients and trigger escalation of care based on pre-set response criteria. Condition-specific systems; for example, the Mortality in Emergency Department Sepsis (MEDS) score were excluded from this review.

Educational programmes for healthcare professionals concerning such early warning systems or TTS.

C

Non-use of the systems or the use of alternative systems of physiological monitoring.

Non-use or use of alternative educational programmes concerning early warning systems or TTS.

O

• Extent of use of early warning systems or TTS

• Types of early warning systems or TTS in use

• Number and type of clinical guidelines (regional, national, international) related to such systems

• Clinical outcomes

 ▪ Death

 ▪ Critical illness (collapse – cardiac or respiratory arrest, haemorrhage, sepsis etc.)

 ▪ Admission to intensive care unit (ICU)

 ▪ Length of hospital stay (days)

• Sensitivity of early warning systems or TTS for adverse outcome/critical illness criterion

• Specificity of early warning systems or TTS for adverse outcome/critical illness criterion

• Positive predictive value of early warning systems or TTS for adverse outcome/critical illness criterion

• Negative predictive value of early warning systems or TTS for adverse outcome/critical illness criterion

• Economic measures of healthcare:

 ▪ Use of healthcare resources associated with early warning systems or TTS use, including direct medical resource costs (staff time, education time and cost, additional referrals), indirect costs (associated with loss of productivity) and other non-medical costs (e.g. patient out-of-pocket expenses)

 ▪ Cost savings, cost effectiveness measures such as Incremental Cost-Effectiveness Ratios (ICERs), Quality Adjusted Life Years (QALYs)

• Types of education programmes

• Strategies and methods to evaluate education programmes of early warning systems or TTS

S

The following six types of studies were included:

a. Descriptive studies – types and use of systems: Studies that described types or variety of early warning systems or TTS used and the extent to which they were used in clinical practice.

b. Descriptive studies – compliance : Studies that described compliance with early warning systems or TTS in clinical practice.

c. Descriptive studies – education programmes : Studies that described education programmes to train healthcare professionals in delivering early warning systems or TTS.

d. Effectiveness studies : Studies that examined the effectiveness of an early warning system or TTS on outcomes for adults admitted to the ED, following triage and that had a controlled design (i.e., RCTs, non-RCTs, controlled before-and-after studies, interrupted time series designs and cohort studies with historical controls). Studies that evaluated the effects of the system on relevant outcomes without control (e.g. case series, cohort studies without historical control) were included in the descriptive category.

e. Development and validation studies : Development studies were defined as studies that focused on the development of early warning systems or TTS while validation studies assessed the predictive ability of such systems. Studies in this category needed to include adult patients both with and without the reference outcome (such as admission to intensive care or mortality) or were otherwise considered a descriptive study. For the purpose of classification, we regarded studies as ‘development’ studies if reference ranges, parameters, and/or design of scoring systems were identified based on the outcomes of the study sample (for example, through the use of receiver operating characteristics [ROC] curves). In validation studies, such reference criteria were already determined and their predictive ability was evaluated in a new sample of patients.

f. Health economics : Full economic evaluation studies (cost-effectiveness analysis, cost-utility analysis and cost-benefit analysis), cost analysis and comparative resource use studies comparing early warning systems or TTS to one or more standard treatments. These may have included any study that met the eligibility criteria for the review of effectiveness; hence studies in other categories might have been also been included here.