A survey of schoolchildren's exposure to secondhand smoke in Malaysia

BMC Public Health

Table 1 Description of the selected sample population of Malaysian schoolchildren

Characteristics	Number opted out of study (n = 721)^{I, a}	Number consented to salivary cotinine study (n=1064)^II	Total^III (n = 1785)
Mean age (years ± SD)	10.7 ± 0.6	10.7 ± 0.6	10.7 ± 0.6
Gender
Boys	316 (43.8)	448 (42.1)	764 (42.8)
Girls	380 (52.7)	605 (56.7)	985 (55.2)
Missing	25 (3.5)	11 (1.0)	36 (2.0)
Family structure
Both parents	651 (90.3)	997 (93.7)	1648 (92.3)
Single parent	21 (2.9)	27 (2.6)	48 (2.7)
Others	30 (4.1)	40 (3.8)	70 (3.9)
Missing	19 (2.6)	-	19 (1.1)
Ethnicity
Malay	635 (88.1)	958 (90.0)	1593 (89.2)
Others	67 (9.3)	106 (10.0)	173 (9.7)
Missing	19 (2.6)	-	19 (1.1)
Location
Urban	435 (60.3)	688 (64.7)	1123 (62.9)
Rural	286 (39.7)	376 (35.3)	662 (37.1)
Home smoking characteristics ⁺⁺
Non-smoking households	377 (52.3)	446 (41.9)	823 (46.1)
Smoking households	290 (40.2)	501 (47.1)	791 (44.3)
Missing	54 (7.5)	117 (11.0)	171 (9.6)
Family income ⁺⁺
Low	319 (44.2)	529 (49.7)	847 (47.6)
Medium	274 (38.0)	326 (30.6)	601 (33.7)
High	88 (12.2)	144 (13.5)	232 (13.0)
Missing	40 (5.5)	65 (6.1)	105 (5.9)

Values are in numbers (percentages)
SD: Standard Deviation
Chi-square test performed between column ^I and ^II (excluding missing values)
⁺⁺: Chi-square outcome for column ^I and ^II was p < 0.05 for home smoking characteristics and family income group
** The 3 categories in the variable Family income was derived using cut-off points obtained from the recent data of Economic Planning Unit, Prime Minister Department Malaysia. The average income is RM3686. Family income lower than RM3000 per month is categorised as low income, RM3000 to RM5000 is categorised as middle income and income of more than RM5000 is categorised as high income group
^a Column I represents 721 children which includes 531 children who opted out of the study, 82 children whose saliva samples could not be collected and108 children who did not provide sufficient saliva sample for laboratory analysis

ISSN: 1471-2458