Perinatal Cat and Dog Exposure and the Risk of Asthma and Allergy in the Urban Environment: A Systematic Review of Longitudinal Studies

Table 2

Evaluating the role of bias in the included studies.

Study	Aichbhaumik [20]	Schönberger [21]	Bisgaard [22]	Gern [23]	Bufford [24]	Pohlabeln [25]	Kerkhof [26]	Nafstad [27]	Remes [28]
Methods for selecting study participants
Appropriate source population
Inclusion and exclusion criteria
Methods for measuring exposure and outcome variables
Appropriate exposure measurement
Appropriate outcome measurement
Methods to deal with design-specific sources of bias
Recall bias	NI	NI	NA	NI	NI	×	NI	NI	NI
Interviewer bias	NI	NI	NI	NI	NI	NA	NA	NA	NA
Loss to followup			(1)✓×		×	NA	✓×	✓×
Blinding	NA	NA	NI	NI	NI	NA	NA	NA	NA
Methods to control confounding
Appropriate design		✓×	×	✓×	✓×	✓×	✓×		✓x
Appropriate analytical methods	✓×		×				✓×	✓×
Statistical methods (excluding confounding)
Appropriate statistics	✓×	✓×			✓×		✓×
Conflict of interests
Declarations of conflict of interests		×		×	×	×	×	×	×
Identification of funding sources
NHMRC evidence grading (ref)
Levels	III-2	III-2	III-2	III-2	III-2	III-2	III-2	III-2	III-2

NA: not applicable; NI: not described in article.
: adequate; ✓×: poor; ×: not done.