Table 2.
Risk of bias table: modified Newcastle Ottowa
| Author and year | Representativeness of intervention group (selection bias) | Control group | Representativeness of control group (selection bias) | Comparability of intervention and control group | Adequate assessment of outcome | Adequate follow-up | Reporting | Generalizability | Conflicts of interest | |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Lockyer L et al., (2014) [65] | Unclear | High | N/A | N/A | Low | N/A | Detailed | Good | No |
| 2 | Douglas A & McCann I, (1996) [66] | High | High | N/A | N/A | Low | N/A | Adequate | Good | No |
| 3 | Beaumont B (1979) [63] | Unclear | High | N/A | N/A | Low | N/A | Incomplete | Potential | No |
| 4 | Eskin F, (1974) [64] | Low | High | N/A | N/A | Low | Low | Detailed | Limited | No |
| 5 | Baker M et al. (1997) [67] | Low | Low | Unclear | Low | Low | Low | Limited | Limited | No |
| 6 | Hilton S et al. (1997) [58] | N/A | N/A | N/A | N/A | High | N/A | Detailed | N/A | Yes |
| 7 | Freeman et al. (2002) | Low | High | N/A | N/A | Low | Low | Adequate | Limited | No |
| 8 | Bellman L (2002) [60] | High | High | N/A | N/A | Low | N/A | Detailed | Limited | Yes |
| 9 | Wilkinson D (2001) [61] | Low | N/A | N/A | N/A | Low | Low | Adequate | Potential | Yes |
| 10 | White CD et al. (2007) [62] | Unclear | High | N/A | N/A | Low- | N/A | Incomplete | Limited | Yes |
| 11 | Gardiner M et al. (2006) [48] | Unclear | High | N/A | N/A | High- | Unclear | Detailed | Potential | No |
| 12 | Straume et al. (2010) [50] | Low | High | N/A | N/A | Low | Low | Detailed | Potential | No |
| 13 | Straume and Shaw (2010) [49] | Low | Low | Unclear | Unclear | Low | Unclear | Detailed | Potential | No |
| 14 | Felix H et al. (2003) [70] | Unclear | High | N/A | N/A | Low | N/A | Adequate | Potential | No |
| 15 | MacIsaac et al. (2000) [71] | Unclear | High | N/A | N/A | Low | N/A | Adequate | Potential | Yes- |
| 16 | Bregazzi R and Harrison (2005) [38] | Low | High | N/A | N/A | Unclear | Unclear | Poor | Limited | No |
| 17 | Kahn TR et al. (2010) [39] | Low | High | N/A | N/A | Low | Low | Detailed | Limited | No |
| 18 | Crouse BJ and Munson RL (2006) [40] | Low | High | N/A | N/A | Low | Unclear | Adequate | Potential | No |
| 19 | Robinson M and Slaney GM (2013) [41] | High | High | N/A | N/A | Low 2X Data sets | High | Adequate | Potential | Yes |
| 20 | Rabinowitz et al. (2005) [32] | Low | Low | Unclear | Unclear | Low | Low | Adequate | Potential | Yes |
| 21 | Mathews M et al. (2008) [33] | Low | High | N/A | N/A | Low | Low- | Detailed | Potential | Yes |
| 22 | Quinn KJ et al. (2011) [34] | Low | Low | Unclear | Unclear | Low | High | Adequate | Potential | Yes |
| 23 | Landry et al. (2011) [35] | Low | Low | Unclear | Low | Low | High | Detailed | Limited | Yes |
| 24 | Magnus JH & Tollan A (1993) [36] | Low | High | N/A | N/A | High | Low | Adequate | Potential | Yes |
| 25 | Stearns et al. (2000) [37] | Low | High | N/A | N/A | Low | Unclear | Limited | Potential | Yes |
| 26 | Halaas et al. (2008) [42] | Low | High | N/A | N/A | Low- | Unclear- ‘ | Detailed | Good | Yes |
| 27 | Smucny J et al. (2005) [43] | High | Low | Low | Unclear | Low | High | Adequate | Good | Yes |
| 28 | Adkins et al. (1987) [44] | Low | Low | Unclear | Unclear | Low | Low | Adequate | Potential | Yes |
| 29 | Wearne S et al. (2010) [46] | Low | High | N/A | N/A | Low | Low | Detailed | Limited | Yes |
| 30 | Charles et al. (2005) [45] | Low | High | N/A | N/A | Low | Low | Adequate | Potential | No |
| 31 | Morris CG et al. (2008) [47] | Low | Low | Low | Low | Low | Unclear | Detailed | Potential | No |
| 32 | Barclay et al. (1994) [51] | Low | Low | Unclear | Unclear | High- | Unclear | Poor | Limited | Yes |
| 33 | Paul Green (2015) [52] | Unclear | N/A | N/A | N/A | High | Low | Limited | Potential | Unclear |
| 34 | Harrison J and Redpath L (2002) [68] | High | High | N/A | N/A | Unclear | Low | Adequate | Potential | No |
| 35 | Delacourt L and Savage R (2002) [69] | Low | High | N/A | N/A | Unclear | Low | Adequate | Potential | No |
| 36 | Matsumoto M et al. (2008) [21] | Low | Low | Low | Unclear | Low | Low | Detailed | Good | No |
| 37 | Matsumoto M et al. (2008) [22] | Low | High | N/A | N/A | Low | Low | Detailed | Good | No |
| 38 | US department of Health and Human services Health resources and services administration (2012) [23] |
Unclear | High | N/A | N/A | High | Low | Limited | Potential | Yes |
| 39 | Pathman D et al. (1992) [24] | Low | Low | Unclear | High | Low | Low | Detailed | Good | Yes |
| 40 | Cullen TJ et al. (1997) [25] | Low | High | N/A | N/A | Low- | Low | Detailed | Good | No |
| 41 | New Zealand Ministry of Health (2012) [26] | Unclear | High | N/A | N/A | High | Unclear | Limited | Potential | No |
| 42 | Dunbabin JS et al. (2006) [27] | High – | High | N/A | N/A | Low | Low | Adequate | Potential | Yes |
| 43 | Jackson J et al. (2003) [28] | Low | Low | Low | High | Low | Low | Adequate | Limited | NO |
| 44 | Mathews M et al. (2013) [29] | Low | Low | Low | Low | Low | Low | Adequate | Good | Yes |
| 45 | Navin TR and Nichols AW (1977) [30] | Low | High | N/A | N/A | Low | Low | Detailed | Limited | Yes |
| 46 | Pathman et al. (2004) [31] | High | Low | Low | Low | Low | Low | Adequate | Good | No |
| 47 | WONCA (2010) [53] | Unclear | High | N/A | N/A | Unclear | Unclear | Limited | Limited | No |
| 48 | Pena S et al. (2010) [54] | Unclear | High | N/A | N/A | Unclear | Unclear | Limited | Limited | No |
| 49 | Wilson et al. (1998) [55] | Unclear | High | N/A | N/A | High | Unclear | Limited | Limited | No |
| 50 | Hutten – Czapski (1998) [56] | N/A | N/A | N/A | N/A | High | Unclear | Limited | Limited | No |
| 51 | Anderson M & Rosenberg (1990) [57] | N/A | N/A | N/A | N/A | High | Low | Detailed | Limited | No |