Restrictions on smoking at home and urinary cotinine levels among children with asthma

OBJECTIVES

The purpose of this study was to determine the extent to which various levels of restrictions on smoking in the home may be associated with children's exposure to environmental tobacco smoke (ETS).

METHODS

The methodology consisted of a cross-sectional survey involving 249 children with asthma aged 1 to 11 attending hospital outpatient clinics, with at least one parent who smoked, linked to the child's urinary cotinine to creatinine ratios (CCR).

RESULTS

After adjustment for child's age, mother's smoking status, and total parental daily cigarette consumption, a total ban was associated with significantly lower urinary CCR levels (7.6 nmol/mmol) than bans with exceptions or limited smoking in the home. Where exceptions to bans were made (14.9 nmol/mmol), children's urinary CCR levels were no different from homes in which smoking was allowed in rooms the child rarely frequented (14.1 nmol/mmol). These two intermediate levels of restriction were in turn associated with significantly lower CCR levels than unrestricted smoking in the home (26.0 nmol/mmol).

CONCLUSIONS

Making exceptions to bans on smoking at home measurably undermines the protective effect of a ban. However, making some exceptions to a ban and limiting smoking to rooms where the child rarely goes may result in reduced exposure to ETS, compared with unrestricted smoking.

Relationship of smoking and albuminuria in children with insulin-dependent diabetes

Recent evidence suggests the rise in urinary albumin excretion preceding diabetic nephropathy may represent a continuum. We therefore studied factors relating to albumin excretion rate in children with insulin-dependent diabetes. Normal overnight albumin excretion rate was determined in 690 healthy schoolchildren. The 95th centile was 7.2 micrograms min-1. Patients included 169 children with IDDM aged 12.4 +/- 3.1 years who performed 4.8 +/- 0.4 overnight collections during 15 +/- 0.5 months and were analysed cross sectionally. They were stratified accordingly to mean albumin excretion rate: normal < 7.2 micrograms min-1, borderline 7.2-20 micrograms min-1, microalbuminuria 20-200 micrograms min-1; 96/169 patients performed 6.4 +/- 0.2 overnight collections during 24 months follow-up and were analysed longitudinally. Cigarette smoking was determined by history and urine cotinine levels. Smoking correlated with albumin excretion rate, independent of age and other variables, in cross-sectional and longitudinal analysis (p < 0.003). Smoking was more prevalent in the borderline albuminuria and microalbuminuria groups (p < 0.004, p < 0.001). Mean HbA1c during follow-up and mean HbA1c since diagnosis were significantly higher in the microalbuminuric group, compared with the normal patient group. HbA1c since diagnosis, mean blood pressure, lipoprotein(a), and apolipoprotein B did not correlate with albumin excretion rate, after controlling for other variables. Our findings highlight the continuing need for strategies to prevent smoking in this age group.