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Table 1 Operationalisation of the items extracted

From: Restrictions and their reporting in systematic reviews of effectiveness: an observational study

Item

Categories

Explanation

Named article as a SR

Yes; No

The authors named their own article as “systematic review” either in the title, abstract, aim or methods section of the article

PRISMA referenced

Yes; No

The PRISMA guideline was explicitly referred to in the abstract or methods section

Date of search reported

Yes; No

The date of search (at least month and year) was reported

Full search strategy available

Yes; No

A complete and reproducible search strategy was available for at least one database. It was not sufficient to present only keywords or search strings. The appendix and/or protocol were only considered if explicitly referred to

Assessment of validity

Yes; No

The validity of the included studies (e.g., risk of bias/methodological quality) was assessed and presented in the SR

Flow chart available

Yes; No

A flow chart was presented in the methods, results or in the appendix (which was only considered if explicitly referenced)

Restriction of publication period

Not reported; Without restriction of period; With restriction of period

Regardless of whether the publication period was restricted, the SR clearly stated which period was considered. If the publication period was restricted, the years under consideration had to be stated. If the publication period was restricted in one database only or the author searched the database from the date of inception (e.g. Medline 1996), the item was classified as “without restriction of period”

Restriction of publication period justified

Yes; No

If the publication period was restricted:

In the methods section, an explicit justification why the restriction was chosen had to be provided

Restriction of study type

Not reported; Only RCTs included; NRSI and RCTs included

The included study types were reported

Eligibility of study type justified

Yes; No

Regardless of whether only RCTs or NRSIs & RCTs were considered:

In the methods section, an explicit justification why the restriction was chosen had to be provided

Restriction of language

Not reported; Without language restriction; With language restriction

Any language restriction had to be reported in the methods section, either in the eligibility criteria or the search strategy. The appendix and/or protocol were only considered if explicitly referred to

Language restriction justified

Yes; No

If there was a language restriction:

In the methods section, an explicit justification why the restriction was chosen had to be provided

Point of language restriction

Unclear; Search strategy; Screening

If there was a language restriction:

Was the restriction described in the search strategy or the screening process? If the methodical approach was unclear or it was not possible to retrace whether the language restriction was applied during the search or the screening, the item was evaluated as “unclear”

Failed to report at least one of the restrictions considered

Yes; No

This item is a combination of the three items "restriction of publication period", "restriction of study type", and " restriction of language". If at least one of these items was categorised as “not reported” this item was classified as “Yes”

  1. SR Systematic Review, NRSI Nonrandomized Studies of Interventions, RCTs Randomized Controlled Trials