The evidence presented here is derived from a systematic review published by Burke (2012) that assessed the effect of exposure of children to passive smoke from their parents or household members on their risk of developing asthma and/or wheeze at different stages of childhood.
The systematic review included 71 longitudinal primary studies published over the period from 1985 up to 2012.
Thirty-one of the included studies assessed wheeze as its outcome, 32 studies assessed asthma, and eight assessed both asthma and wheeze.
Thirty-seven of the studies assessed exposure to prenatal maternal smoking, 26 assessed postnatal maternal smoking, seven assessed postnatal paternal smoking, and 28 assessed household smoking.
Thirty-two of the included studies were conducted in Europe.
The methodological quality of the 71 studies, as judged by the Newcastle-Ottawa score, gave an overall median score of 6 (range 5─7). Before the quality was evaluated, a score of ≥7 had been selected as of high quality and scores of <7 as of lower quality. Therefore, 31 (44%) studies were judged to be high quality.