Study | Selection | Comparability (can have up to 2 stars) | Exposure | Rating | |||||
Is the case definition adequate? (*) | Representativeness of the cases (*) | Selection of controls (*) | Definition of controls | Comparability of cases and controls (**) | Ascertainment of exposure (*) | Same method of ascertainment for cases and controls (*) | Non-response rate (*) | ||
Smith et al9 | * | * | * | * | * | * | – | – | Poor |
Weichenthal et al38 | – | – | – | * | * | * | * | * | Poor |
Wade et al48 | * | – | * | * | * | * | * | * | Good |
Thresholds for converting the Newcastle-Ottawa scales to Agency for Healthcare Research and Quality standards (good, fair, and poor): Good quality: 3 or 4 stars in Selection domain AND 1 or 2 stars in Comparability domain AND 2 or 3 stars in Exposure domain. Fair quality: 2 stars in Selection domain AND 1 or 2 stars in Comparability domain AND 2 or 3 stars in Exposure domain. Poor quality: 0 or 1 star in Selection domain OR 0 star in Comparability domain OR 0 or 1 star in Exposure domain.