Table 2.
Assessment of the quality of all studies included in the review
| Study no. | Author, Year [References] | Selection bias | Study design | Confounders | Blinding | Data collection methods | Withdrawals and drop-outs | Final rating |
|---|---|---|---|---|---|---|---|---|
| 1 | Adam et al. 2009 [39] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 2 | Adam et al. 2007 [24] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 3 | Adegnika et al. 2011 [25] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 4 | Alemu and Mama, 2016 [40] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 5 | AlIi et al. 2010 [41] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 6 | Alim et al. 2015 [42] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 7 | Amodu et al. 2012 [43] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 8 | Bedu-Addo et al. 2014 [44] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 9 | Boel et al. 2012 [45] | 1 | 1 | 2 | 2 | 1 | 2 | 1 |
| 10 | Carvalho et al. 2010 [15] | 1 | 2 | 2 | 2 | 1 | 2 | 1 |
| 11 | Cavasini et al. 2006 [46] | 1 | 2 | 2 | 2 | 1 | 2 | 1 |
| 12 | Degarege et al. 2012 [16] | 2 | 3 | 1 | 1 | 2 | 2 | 1 |
| 13 | Fowkes et al. 2008 [47] | 2 | 3 | 3 | 2 | 2 | NA | 3 |
| 14 | Giha et al. 2000 [48] | 2 | 1 | 3 | 2 | 1 | 2 | 2 |
| 15 | Gupte et al. 2012 [49] | 2 | 2 | 3 | 2 | 2 | 2 | 2 |
| 16 | Igbeneghu et al. 2012 [18] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 17 | Jeremiah et al. 2012 [19] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 18 | Joshi et al. 1987 [50] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 19 | Kaisar et al. 2013 [51] | 1 | 3 | 2 | 2 | 1 | NA | 2 |
| 20 | Kassime & Ejezie, 1982 [52] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 21 | Loscertales & Brabin, 2006 [22] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 22 | Lwanira et al. 2015 [53] | 1 | 1 | 1 | 2 | 2 | 1 | 1 |
| 23 | Migot-Nabias et al. 2000 [54] | 2 | 1 | 1 | 2 | 1 | 2 | 1 |
| 24 | Migot-Nabias et al. 2006 [55] | 2 | 1 | 1 | 2 | 1 | 2 | 1 |
| 25 | Missinou et al. 2003 [56] | 2 | 1 | 2 | 2 | 1 | 2 | 1 |
| 26 | Nwauche et al. 2011 [57] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 27 | Ojurongbe et al. 2011 [17] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 28 | Panda et al. 2012 [12] | 2 | 3 | 2 | 2 | 1 | NA | 2 |
| 29 | Panda et al. 2011 [58] | 2 | 3 | 2 | 2 | 1 | NA | 2 |
| 30 | Pant et al. 1992a [59] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 31 | Pant et al. 1992b [60] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 32 | Pant et al. 1997 [61] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 33 | Pathirana et al. 2004 [62] | 2 | 3 | 3 | 1 | 1 | NA | 3 |
| 34 | Rabha et al. 2012 [63] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 35 | Senga et al. 2007 [23] | 2 | 3 | 3 | 2 | 2 | NA | 3 |
| 36 | Singh et al. 1995 [64] | 2 | 1 | 2 | 2 | 1 | 2 | 1 |
| 37 | Tadesse & Tadesse, 2013 [14] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 38 | Tekeste & Petros, 2010 [65] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 39 | Thakur & Verma, 1992 [66] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 40 | Ukaga et al. 2007 [67] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 41 | Uneke et al. 2006 [68] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
| 42 | Zerihun et al. 2011 [13] | 2 | 3 | 3 | 2 | 1 | NA | 3 |
1 = strong; 2 = moderate; 3 = weak; NA = not applicable