From: The value of fractional exhaled nitric oxide in occupational diseases – a systematic review
Study | Selection bias | Type of study | Confounders | Data collection methods | Blinding | Dropout rate | Grading |
---|---|---|---|---|---|---|---|
Al Badri et al., 2020 [34] | Weak | Longitudinal | Strong | Strong | Moderate | Moderate | Moderate |
Dressel et al., 2007 [35] | Moderate | Longitudinal | Moderate | Moderate | Moderate | Strong | Strong |
Dressel et al., 2009 [36] | Moderate | Longitudinal | Strong | Strong | Moderate | Weak | Moderate |