Passive smoking

The objective of this study was to analyse the influence some environmental factors can have on the incidence of some important childhood diseases (recurrent otitis, headache/migraine, sinusitis and pneumonia). 
As a result of the database used by all paediatricians in the Pedianet network which allows detailed queries on patient archives, the study was carried out as a retrospective case-control study. 

The definitions of the pathologies being studied were: 

- recurrent otitis media (OMR) (ICD9 381 ): 
* for children below 1 year of age: at least one episode; 
* for children over 1 year of age: 3 or more episodes in 6 months or 4 or more episodes in a year; 
- headache / migraine (ICD9 346; ICD9 784); 
- pneumonia (ICD9 485): at least 2 episodes in a year; 
- sinusitis (ICD9 461; ICD9 473): at least one episode; 

A retrospective analysis of existing databases allowed us to define the size of the sample to be studied (cases and controls) 
31 paediatricians were thus recruited each able to contribute 50-70 patients for a maximum grand total of 1884 cases or controls. 
Paediatricians were enrolled who had an electronic clinical archives from at least the first of January 1999. 
Cases were identified retrospectively in the electronic archives of each doctor based on diagnoses made. For each case two age and sex matched controls were then selected. 
Data for risk factors studied were collected using a questionnaire sent to the children’s parents containing questions about the child’s: 
- social background 
- personal details 
- child’s schooling 
- medical history particularly about pathology which could influence the illnesses being studied 
- information about parents or other household member smoking habits. 
Once these anonymous questionnaires were returned, the paediatrician sent them to Società Servizi Telematici di Padova where they were analysed with the assistance of the Department of Epidemiology and Biostatistics of the University of Rotterdam. 
31 paediatricians, with 1884 patients (cases and controls) were recruited. 28 paediatricians were able to gather completed questionnaires used I the analysis. 1086 questionnaires were completed in total, which corresponded to the same number of patients (57.6% of the total number initially selected). 
In our study we did ot find any association between recurrent otitis media (ROM), breastfeeding, illness or allergy in parents (including ROM). Whereas we did find a significant association between the presence of ROM in brother’s or sisters (OR 4.95; 95% CI: 1.38-17.74) and passive smoking (OR 1.91; 95% CI: 1.01-3.63) and otitis. In particular, passive smoking seems to be associated with otitis even when the family members smoke very few sigarettes. This result seems to go against previous evidence, particularly in the first year of life. However, this data needs confirmation and it could be that there is a familial susceptibility to otitis associated “qualitatively” to passive smoking and not dependant o the number of cigarettes. 
We did not find any association between passive smoking and sinusitis. Our results seem to confirm those of others in highlighting that sinusitis (acute and chronic) increases with use of cigarettes, but not with exposure to passive smoking. The presence of sinusitis in the father does increase the risk of sinusitis I the child almost 4 times (OR 3.95; 95% CI: 1.43-10.9). 
Although numerous authors have shown an association between lower respiratory tract infections and passive smoking, we have not made any similar observations as regards pneumonia. We do however feel that our sample size may not be large enough to make a precise evaluation as diagnostic difficulties may also play a role in discordant results from different studies. 
Headache is associated with a family history of headaches as predictable (risk increased about 4 times with both maternal or paternal family history), but not with passive smoking or other socio-environmental factors even after multivariate analysis. 
The paternal unemployment rate in our study was on average 2-3% showing a certain homogeneity in the study population as regards socio-econmic factors, thus it was not possible to stratify risk by categories.