Table 4.

Risk bias assessment in included studies.

No.	Author, year	Selection Bias	Study Design	Confounders	Blinding	Data collection methods	Withdrawals and drop-outs	Final rating
1.	Sankaranarayanan et al., 1998[17]	+++	+++	+	+	+++	+	3
2.	Basu et al., 2003[6]	+++	+++	+	+	+	+++	3
3.	Sankaranarayanan et al., 2003[18]	+++	+++	+	+	+	+	3
4.	Sankaranarayanan et al., 2004[19]	+++	+++	+	+	+	+++	3
5.	Sankaranarayanan et al., 2004[20]	+++	+++	+	+	+	+	3
6.	Basu et al., 2006[9]	+++	+++	+	+	+	+++	3
7.	Kamal et al., 2007[21]	+++	+++	+	+	+	+++	3
8.	Nene et al., 2007[22]*	++	+	+	+	+	+	1
9.	Sankaranarayanan et al., 2007[11]*	++	+	+	+	+	+	1
10.	Bhatla et al., 2009[5]	+++	+++	+	+	+	+++	3
11.	Gravitt et al., 2010[24]	+++	+++	+	+	+	+++	3
12.	Kumar et al., 2011[10]	+++	+++	+	+	+	+++	3
13.	Deodhar et al., 2012[25]	++	+++	+	+	+	+	2
14.	Basu et al., 2013[26]	++	+++	+	+	+	+++	3
15.	Shastri et al., 2013[32]*	+	+	+	+	+	++	1
16.	Ghosh et al., 2014 [31]	+++	+++	+	+	+	+	3
17.	Jeronimo et al., 2014[27]	+++	+++	+	+	+	+	3
18.	Satyanarayanan et al., 2014[28]	++	+++	+	+	+	+++	3
19.	Basu et al., 2015[29]	+++	+++	+	+	+	+	3
20.	Poli et al., 2015[30]	+++	+++	+	+	+	+++	3

⁺strong;

⁺⁺moderate;

⁺⁺⁺weak;

^*randomized controlled trial; 1= strong; 2=moderate; 3=weak