Editorial Note on: Spinal Cord (2014) 52, 722–728; doi:10.1038/sc.2014.92; published online 5 August 2014

This issue of Spinal Cord presents a systematic review, Psychological variables associated with employment following spinal cord injury: a meta-analysis.1 This is an important contribution to the evidence base on vocational rehabilitation in the SCI field.

What does a systematic review tell us? It provides us with results from the included studies—nothing more, and hopefully nothing less.

What characterizes a systematic review? Three main components must be present: a systematic search of the literature, clear inclusion/exclusion criteria and an assessment of the quality of the included studies.2, 3, 4

It is essential to identify all relevant literature. Failure to identify all relevant studies, - risks deficient or even possibly wrong conclusions.

How do we know if the search identified all relevant studies? A transparent methodology is mandatory.2, 3, 4 It is essential that the full search strategy and the table of excluded studies are presented. Two authors must preferably screen the search results (titles and abstracts), in order to reduce the chances of missing studies. Regular updating is important to include new studies as they appear.

Is the systematic review in this issue1 limited by the search strategy? The omission of terms related to psychological factors and quality of life in the search opens the possibility of relevant articles potentially not being found, that is, articles that did not include any of the search terms in their title or abstract. Since employment, work, return –to- work are variables (among several other factors, sex, age, marital status, income, and so on) used to explore what influences psychological health, life satisfaction, quality of life and so on, employment may not be mentioned in the title or abstract if not assessed as a main outcome.

High-quality systematic reviews are useful to readers, researchers within the field, clinicians and interested persons to get a reliable answer to the question—even when the answer may be a knowledge gap. A systematic review should include a meta-analysis where it is sensible and meaningful, as in this issue.

A systematic review provides us with results from the included studies—nothing more, and hopefully nothing less.