Study | Selection | Comparability | Outcome | Score* | |||||
---|---|---|---|---|---|---|---|---|---|
 | Representativeness of exposed cohort | Selection of non exposed cohort | Ascertainment of exposure | Outcome not present at outset of study |  | Assessment | F/U Length | Adequacy of F/U |  |
Arshad 2014 [7] | * | * | * | * | ** | * | * | * | 9 |
Jones 2004 [10] | * | * | * | * | ** | * | * | * | 9 |
Orus 2000 [12] | * | * | * | * | Â | * | * | * | 7 |
Santos 1998 [13] | * | * | * | * | * | * | * | Â | 7 |
Sessions 2005 [14] | * | * | * | * | Â | * | * | * | 7 |
Spector 1995 [15] | * | * | * | * | ** | * | * | * | 9 |
Spriano 1997 [16] | * | * | * | * | * | * | * | * | 8 |