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. |