Table 2

Risk of bias assessment of individual studies (n=21)

Article1. Was the purpose of the study clearly defined in the abstract and introduction?*2. Was the sampling frame a true or close representation of the target population?3. Was some form of random selection used to select the sample, OR was a census undertaken?4. Was the likelihood of non-response bias minimal?5. Were data collected directly from the subjects?6. Was an acceptable case definition used in the study?7. Was the study instrument that measured valid and reliable?8. Was the same mode of data collection used for all subjects?9. Was the length of the shortest prevalence period for the parameter of interest appropriate?10. Were the numerator(s) and denominator(s) for the parameter of interest appropriate?
Pirson and Pirlot (1990)18 YesNoNoYesPartiallyNoPartiallyPartiallyYesYes
Linenger et al (1993)19 PartiallyNoNoNoPartiallyYesPartiallyYesYesYes
Shwayhat et al (1994)20 YesYesPartiallyYesPartiallyYesPartiallyYesYesYes
Kragh et al (1996)22 YesNoPartiallyNoNoYesNoNoYesYes
Miser et al (1995)21 YesNoNoNoYesPartiallyNoNoYesNo
Ensign et al (2000)24 PartiallyNoNoNoYesNoNoYesNoYes
Schumacher et al (2000)23 YesNoNoNoNoYesPartiallyYesYesYes
Kotwal et al (2004)25 PartiallyNoNoNoPartiallyYesNoPartiallyYesPartially
Hughes and Weinrauch (2008)26 YesNoNoNoNoNoNoPartiallyYesPartially
Lynch and Pallis (2008)37 YesPartiallyNoNoNoNoPartiallyYesYesNo
Hollingsworth (2009)28 YesYesNoYesYesPartiallyNoYesNoNo
Reynolds et al (2009)27 YesNoNoNoPartiallyYesNoYesYesYes
Abt et al (2014)29 YesPartiallyNoYesYesYesNoYesYesPartially
Teyhen et al (2015)30 YesYesPartiallyNoPartiallyYesPartiallyYesYesNo
Lovalekar et al (2016)31 YesNoNoNoNoYesNoPartiallyYesNo
Heebner et al (2017)34 YesNoNoNoNoYesPartiallyYesYesPartially
Lovalekar et al (2017)32 YesYesNoNoYesYesPartiallyPartiallyNoNo
Lovalekar et al (2017)33 YesNoNoNoPartiallyYesPartiallyPartiallyYesPartially
Lovalekar et al (2018)35 YesNoNoNoNoYesNoPartiallyYesPartially
Teyhen et al (2018)36 YesYesPartiallyNoPartiallyPartiallyPartiallyPartiallyYesYes
Dijksma et al (2020)17 YesPartiallyPartiallyYesPartiallyYesPartiallyPartiallyYesPartially