Ascertaining asthma status in epidemiologic studies: a comparison between administrative health data and self-report

Table 1 Selected characteristics of participants (N = 1643) and percentages corrected for the stratified sampling^a

Characteristics	n	% in Survey sample	% Corrected for stratified sampling^a
Sex
Males	683	41.6	44.0
Females	960	58.4	56.0
Language
French	1550	94.3	93.5
English	93	5.7	6.5
Parental birthplace
In Quebec	1394	84.8	83.4
Outside Quebec	83	5.0	7.4
In and outside Quebec	93	5.7	4.9
Missing	73	4.4	4.3
Area of residence 1987-2011^b
All urban	981	59.7	58.8
All rural	155	9.4	10.4
Urban and rural	501	30.5	30.1
Missing	6	0.4	0.7
Family income 1991 and 2011^c
Quartile 1, on average	128	7.8	9.1
Quartile 2, on average	467	28.4	28.9
Quartile 3, on average	621	37.8	37.2
Quartile 4, on average	405	24.6	23.5
Missing	22	1.3	1.3
Material deprivation index 1987-2011^d
1, most privileged	154	9.4	9.0
2	370	22.5	22.9
3	501	30.5	28.1
4	363	22.1	23.5
5, most deprived	91	5.5	5.5
Missing	164	10.0	11.1
Social deprivation index 1987-2011^d
1, most privileged	135	8.2	8.3
2	472	28.7	29.7
3	455	27.7	26.0
4	348	21.2	21.0
5, most deprived	69	4.2	3.9
Missing	164	10.0	11.0
Maternal education level
Elementary school	442	26.9	27.5
Secondary school	596	36.3	36.2
College	222	13.5	13.3
University	228	13.9	13.4
Missing	155	9.4	9.7
Paternal education level
Elementary school	497	30.2	30.5
Secondary school	479	29.2	28.8
College	158	9.6	9.3
University	312	19.0	19.2
Missing	197	12.0	12.2
Parental history of asthma
No	1390	84.6	78.5
Yes	220	13.4	15.5
Missing	33	2.0	6.0
Number of health services for allergic diseases^e
0	711	43.3	55.9
≥ 1	932	56.7	44.1

^a Frequency distributions based on 1643 participants, corrected by applying weights corresponding to the inverse of the sampling probability from the Quebec Birth Cohort on Immunity and Health for the Survey on Childhood Environment and the Development of Allergic Diseases (stratified sampling among four strata, according to BCG vaccination status and asthma)
^b Determined using the second character of subjects’ residential postal codes (0: rural, ≠ 0: urban) in 1987, 1991 and 2011
^c Estimated by ‘median family income’ from the 1991 and 2011 Canadian census using the 1st three characters of subjects’ residential postal code. The summarized value consists in the average quartile of income over these two times, rounded up to the next integer
^d Estimated by the material and social deprivation indices based on the subjects’ residential postal codes in 1987, 1991 and 2011. The summarized value consists in the average index over these three times, rounded up to the next integer
^e Allergic diseases include allergic rhinitis, eczema, allergic urticaria, and other allergies non-specified; asthma is excluded
Compilation based on data from the ©Government of Quebec, Institut de la statistique du Québec, Survey on Childhood Environment and the Development of Allergic Diseases, 2012 and Quebec Birth Cohort on Immunity and Health, 2017. Institut de la statistique du Québec is not responsible for compilations or interpretation of results

ISSN: 1471-2288