Table 5.6.a: Some advantages and disadvantages of broad versus narrow review questions

 

Broad scope

Narrow scope

Choice of participants 

e.g. corticosteroid injection for shoulder tendonitis (narrow) or corticosteroid injection for any tendonitis (broad)

Advantages:

Comprehensive summary of the evidence.

Ability to assess generalizability of findings across types of participants.

Advantages:

Manageability for review team.

Ease of reading.

 

Disadvantages:

May be more appropriate to prepare an Overview of reviews (see Chapter 22).

Searching, data collection, analysis and writing may require more resources.

Risk of ‘mixing apples and oranges’ (heterogeneity); interpretation may be difficult.

Disadvantages:

Evidence may be sparse.

Findings may not be generalizable to other settings or populations.

Scope could be chosen by review authors to produce a desired result.

 

Definition of an intervention 

e.g. supervised running for depression (narrow) or any exercise for depression (broad)

Advantages:

Comprehensive summary of the evidence.

Ability to assess generalizability of findings across different implementations of the intervention.

Advantages:

Manageability for review team.

Ease of reading.

 

 

Disadvantages:

Searching, data collection, analysis and writing may require more resources.

Risk of ‘mixing apples and oranges’ (heterogeneity); interpretation may be difficult.

Disadvantages:

Evidence may be sparse.

Findings may not be generalizable to other formulations of the intervention.

Scope could be chosen by review authors to produce a desired result.

 

Choice of interventions and comparisons

e.g. alarms for preventing bed-wetting (narrow) or interventions for preventing bed-wetting (broad)

Advantages:

Comprehensive summary of the evidence.

Advantages:

Manageability for review team.

Clarity of objectives and ease of reading.

 

Disadvantages:

May be unwieldy, and more appropriate to present as an Overview of reviews (see Chapter 22).

Searching, data collection, analysis and writing may require more resources.

Disadvantages:

May have limited value when not included in an Overview.