Table 1.

Overlap of original research studies included in the systematic reviews

Author, year	1	2	3	4	5	6	7	8	9	10
1. Abbas et al. 1998 [21]	17	0	9	1	7	10	9	8	3	0
2. Sulsky et al. 2005 [44]		34	12	3	12	14	6	13	0	3
3. Palmer et al. 2007 [22]			38	5	19	18	16	19	4	2
4. Thomsen et al. 2008 [45]				9	4	4	1	3	1	3
5. Lozano-Calderón et al. 2008a [46]					66	18	12	16	5	2
6. van Rijn et al. 2009 [35]						44	21	21	3	3
7. Barcenilla et al. 2012 [41]							37	22	3	0
8. Spahn et al. 2012a [31]								55	2	1
9. You et al. 2014 [43]									8	0
10. Mediouni et al. 2014 [42]										6

Bold numbers are studies included in each SRs

^aIncluded primary studies that were used for the analysis of occupational risk factors, but which were not listed explicitly, e.g., in the form of an evidence table. Consequently all studies from all tables, figures or text were extracted when they were used for the analysis of occupational factors. This was used to determine overlap