Table 2.
Risk of Bias Assessment of Included Studies.
| Author (Year of Publication) | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Total |
| Saikia et al. (2018) | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Lalu et al. (2018) | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 5 |
| Mummadi (2018) | 1 | 0 | UC | UC | 0 | 0 | UC | 0 | 1 |
| Kushwaha et al. (2017) | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 4 |
| Chandra et al. (2015) | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 2 |
| Chandra et al. (2014) | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 4 |
| Tripathi et al. (2012) | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 5 |
| Ghosh et al. (2012) | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 5 |
| Kota et al. (2012) | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 5 |
| Poddar et al. (2011) | 1 | 0 | UC | UC | 0 | 0 | UC | 0 | 1 |
| Saldanha et al. (2010) | 1 | 0 | UC | 1 | 0 | 0 | UC | 0 | 2 |
| Alladi et al. (2006) | 1 | 1 | UC | 1 | 0 | 0 | UC | 0 | 3 |
| Rajkumar et al. (1997) | 1 | 1 | UC | 1 | 0 | 0 | UC | 0 | 3 |
| Shaji et al. (1996) | 1 | 1 | UC | 1 | 0 | 0 | UC | 0 | 3 |
| Mean: 3.1, Median: 3 |
Q1: Were the criteria for inclusion in the sample clearly defined? Q2: Were the study subjects and the setting described in detail? Q3: Was the exposure measured in a valid and reliable way? Q4: Were objective, standard criteria used for measurement of the condition? Q5: Were confounding factors identified? Q6: Were strategies to deal with confounding factors stated? Q7: Were the outcomes measured in a valid and reliable way? Q8: Was appropriate statistical analysis used? (1—Yes, 0—No, NA—Not applicable, UC—Unclear).