Association between secondhand smoke exposure and abnormal cervical cytology: A one-to-one matched case-control study

The aim was to evaluate the association between secondhand smoke (SHS) exposure and abnormal cervical cytology among Chinese adult women.

A one-to-one matched case-control study was conducted with outpatients of the First Hospital of Jilin University between October 2013 to September 2016. In all, 228 cytologic confirmed new cases of abnormal cervical cytology and the equivalent number of age and ethnic matched controls were interviewed about SHS exposure and related factors.

Although 78.3% of all the participants had been exposed to SHS (78.1% subjects vs 78.5% controls), there were no statistical significance of cervical cytological abnormalities and SHS exposure status (never, former, current exposure), exposure intensity in cigarettes per day (none, 1-9, 10-19, and ≥20), SHS exposure duration in years (none, 1-9, 10-19, and ≥20) and the Brinkman Index (BI) (none, 1-99, 100-399, ≥400) between the two groups. The univariate analysis results showed that there were statistical differences between subjects and controls in marital status, sexual frequency in past year, number of sexual partners, age at first intercourse, age at first delivery. The stratified Cox regression model only showed that the age at first sexual intercourse was associated with the cervical cytological abnormalities (OR=1.206, 95% CI: 1.104-1.319).

Studies on the association between SHS exposure and cervical lesions have been equivocal. In this study, the SHS exposure could not be detected as an independent risk factor of abnormal cervical cytology among Chinese adult women.