Trends in passive smoking in cystic fibrosis, 1993-1998

We set out to study trends in exposure to passive smoking in children with cystic fibrosis over a 5-year period. We also evaluated the effects of this exposure on lung function. Cross-sectional data were collected on 52 child ren in 1998 and compared with similar data collected on 56 children in 1993 . Within these two groups, there were 34 children who were studied on both occasions. Data collected included: questionnaire information about family smoking habits; forced expiratory volume in 1 sec (FEV1); forced vital capa city (FVC); and measurements of urinary and salivary cotinine levels. Salivary cotinine was more closely related to family smoking behavior than urinary cotinine concentrations (r for salivary cotinine = 0.54, P < 0.001; r for urinary cotinine = 0.37, P = 0.008). In 1993, 26/56 (46%) households contained at least one smoker (smoking households) compared with 23/52 (44 %) in 1998. In 1993, a median of 15 cigarettes was smoked/day in smoking ho useholds compared to 20 cigarettes/day in 1998. In the longitudinal group, there was a small, nonsignificant reduction in mean urinary cotinine levels (geometric mean, 1993 = 5.03 ng/mL; 1998 = 4.76 ng/mL; P = 0.4). There was no significant difference between the smoking and nonsmoking households in change in lung function over 5 years (fall in FEV1 in smoking households, 10.3% vs. 11.2% in nonsmoking households; P = 0.87). We conclude that in a group of children with cystic fibrosis followed over 5 years, there was little reduction in passive smoking exposure. We did not show a relationship between such exposure and decline in lung function. A larger study will be necessary to determine whether such an effect is prese nt. Pediatr Pulmonol. 2001; 31:133-137. (C) 2001 Wiley-Liss, Inc.