Table 2

Methodological quality appraisal of the studies

Study referencesMethodological itemsScore (%)Adjusted analysisQuality
1233A3B456788A910111212A13141515A
Prospective/retrospective cohort studies
 Tüchsen et al 35 +––+* –+NANA++–+–+ ++* + 67YesHigh
 Tüchsen et al 36 ++–+ –+* NANA++–+–+ +?+ 67YesHigh
 Angersbach et al 37 +–+– NANA++++–––+ –NA– 50NoLow
Case-control studies
 Kleiven et al 38 ++++–++NANA++–––++++ +76YesHigh
 Bourbonnais et al 39 –+++––+NANA++–––+–++ +59YesHigh
Cross-sectional studies
 Higashi et al 40 +++ ++NANA+ –––+ –NA+ 67YesHigh
 Niedhammer et al 41 +++ –+† NANA– –––+ +++ 62YesHigh
 Böckerman and Laukkanen42 ++– –+* NANA– –––+ ++* + 54YesHigh
 Ohayon et al 43 ++– ++NANA– –––+ –++ 54YesHigh
 Eyal et al 44 ++?‡ –+NANA+ –––+ –++ 54YesHigh
 Chan et al 45 +++ NANA+++ +––+ –NA+ 75NoLow
 Koller46 +++ ++NANA– +––+ –NA+ 67NoLow
 Smith et al 47 +++ –+NANA+ –––NA –NA+ 55NoLow
 Colligan et al 48 +++ –+NANA+ –––+ –NA– 50NoLow
 Drake et al 49 ++– –+NANA+ –––+ –NA+ 50NoLow
 Chee and Rampal50 ++–* –+* ++* – –––NA –NA+ 46NoLow
 Lambert et al 51 ++– ––NANA– –+–+ –++ 46NoLow
 Olsen and Dahl52 +–– –+† NANA– –––+ +++ 46NoLow
 Jamal and Baba53 –+– ++NANA+ –––+ –NA– 42NoLow
 Sveinsdottir54 ++– –+NANA– –––+ –NA+ 42NoLow
 Demerouti et al 55 ++– +–* NANA– –––+ –+– 38NoLow
 Aguirre and Foret56 ++?‡ +–NANA– +––– –NA+ 42NoLow
 Drago and Wooden57 ++– ––NANA– –––+ –++ 38NoLow
 Fawer and Lob58 ––+ ––NANA– –––NA –NA+ 18NoLow

  • ↵* Item changed from ‘?’ after information was retrieved from the authors.

  • ↵† Item changed from ‘?’ after a copy of the questionnaire was found on the internet.

  • ↵‡ Not able to establish contact with the corresponding author.