Information archivée dans le Web - canada.ca · Information archivée dans le Web Information...
18
Ce contenu a été archivé le 30 juillet 2013. Information archivée dans le Web Information archivée dans le Web à des fins de consultation, de recherche ou de tenue de documents. Cette dernière n'a aucunement été modifiée ni mise à jour depuis sa date de mise en archive. Les pages archivées dans le Web ne sont pas assujetties aux normes qui s'appliquent aux sites Web du gouvernement du Canada. Conformément à la Politique de communication du gouvernement du Canada, vous pouvez demander de recevoir cette information dans tout autre format de rechange à la page « Contactez-nous ».
Transcript of Information archivée dans le Web - canada.ca · Information archivée dans le Web Information...
Ce contenu a été archivé le 30 juillet 2013.
Information archivée dans le Web
Information archivée dans le Web à des fins de consultation, de recherche ou de tenue de
documents. Cette dernière n'a aucunement été modifiée ni mise à jour depuis sa date de mise
en archive. Les pages archivées dans le Web ne sont pas assujetties aux normes qui
s'appliquent aux sites Web du gouvernement du Canada. Conformément à la Politique de
communication du gouvernement du Canada,
vous pouvez demander de recevoir cette information dans tout autre format de
rechange à la page « Contactez-nous ».
This content was archived on July 30, 2013.
Archived Content
Information identified as archived on the Web is for reference, research or recordkeeping
purposes. It has not been altered or updated after the date of archiving. Web pages that are
archived on the Web are not subject to the Government of Canada Web Standards. As per
the Communications Policy of the
Government of Canada, you can request alternate formats on the "Contact Us" page.
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 30 of 61
Figure 3a: Finished Water Quality Descriptive Results (Jan. 1, 1993 to Dec. 31, 1998) Rossdale plant
(i) Daily mean finished water turbidity(NTU) (span 25 days) 5
(ii) Daily mean finished water particle counts (span 25 days)
(iii) Distribution of observed daily mean (iv) Distribution of observed daily mean finished water turbidity values finished water particle counts
5 25-day span may be interpreted as a weighted moving average, based on surrounding observations within an 25-day interval
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0.00
0.05
0.10
0.15
0.2012/10/97
1/01/98 3/02/98 5/02/98 7/02/98 8/31/98 10/31/98 12/31/980
10
20
30
40
0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32 0.36 0.400
10
20
30
40
50
60
70
80
90
100
Daily Mean Finished Water Turbidity (NTU)
Den
sity
(%
)Pr
opor
tion
(%)
0 10 20 30 40 50 60 700
10
20
30
40
50
60
70
80
90
100
Daily Mean Finished Water Particle Counts
Den
sity
(%)
Prop
ortio
n (%
)
NTU
Parti
cle
Co
unts
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 31 of 61
Figure 3b: Finished Water Quality Descriptive Results (Jan. 1, 1993 to Dec. 31, 1998) E.L. Smith plant
(i) Daily mean finished water turbidity (NTU) (span 25 days)
(ii) Daily mean finished water particle counts (span 25 days)
(iii) Distribution of observed daily mean (iv) Distribution of observed daily mean finished water turbidity values finished water particle counts
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0.00
0.05
0.10
0.15
0.20
1/01/98 3/02/98 5/02/98 7/02/98 8/31/98 10/31/98 12/31/980
10
20
30
40
0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32 0.36 0.400
10
20
30
40
50
60
70
80
90
100
Daily Mean Finished Water Turbidity (NTU)
Den
sity
(%
)Pr
opor
tion
(%)
0 10 20 30 40 50 60 700
10
20
30
40
50
60
70
80
90
100
Daily Mean Finished Water Particle Counts
Den
sity
(%)
Prop
ortio
n (%
)
NTU
Parti
cle
Co
unts
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 32 of 61
Figure 4a: Raw Water Quality Descriptive Results (Jan. 1, 1993 to Dec. 31, 1998) Rossdale plant
(i) Daily mean raw water turbidity (span 60 days) 6
(ii) Daily raw water faecal coliform counts (span 60 days)
(iii) Density plot of observed daily mean (iv) Density plot of observed daily mean raw water turbidity values raw water faecal counts
6 60-day span may be interpreted as a weighted moving average, based on surrounding observations within an 60-day interval
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0
500
1000
1500
200012/10/97
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/980
50100150200250300350 12/10/97
0 100 200 300 400 500 600 700 800 900 10000
10
20
30
40
50
60
70
80
90
100
Daily Mean Raw Water Turbidity (NTU)
Den
sity
(%)
Prop
ortio
n (%
)
0 1000 2000 3000 4000 50000
10
20
30
40
50
60
70
80
90
100
Daily Raw Water Fecal Coliform Counts
Den
sity
(%
)Pr
opor
tion
(%)
NTU
Fec
al C
olif
orm
Co
unts
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 33 of 61
Figure 4b: Raw Water Quality Descriptive Results (Jan. 1, 1993 to Dec. 31, 1998) E.L. Smith plant
(i) Daily mean raw water turbidity (span 60 days)
(ii) Daily raw water faecal coliform counts (span 60 days)
(iii) Density plot of observed daily mean raw (iv) Density plot of observed daily mean raw water turbidity values water faecal counts
0 100 200 300 400 500 600 700 800 900 10000
10
20
30
40
50
60
70
80
90
100
Daily Mean Raw Water Turbidity (NTU)
Den
sity
(%)
Prop
ortio
n (%
)
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0
500
1000
1500
2000
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/980
50100150200250300350
0 1000 2000 3000 4000 50000
10
20
30
40
50
60
70
80
90
100
Daily Raw Water Fecal Coliform Counts
Den
sity
(%)
Prop
ortio
n (%
)
NTU
Fec
al C
olif
orm
Co
unts
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 34 of 61
4.1 b) Environmental parameters
Summary statistics are provided for the environmental parameters in Table 9. Temporal trends
for daily extreme temperatures and precipitation are provided in Figures 5 and 6, respecti vely. Strong
seasonal patterns were apparent for these data, with peaks being observed during the spring and
summer season.
Figures 7 and 8 visually describe the relationship between raw water turbidity and
environmental factors. In general, increases in temperature and precipitation were accompanied by an
increase in raw water turbidity.
Table 9: Summary statistics for environmental parameters (Jan. 1, 1993 to Dec. 31, 1998)
Figure 5: Maximum and minimum daily temperatures (°C) (Jan. 1, 1993 to Dec. 31, 1998) (span=25 days) (refer to footnote 5)
Figure 6: Daily precipitation (mm) (Jan. 1, 1993 to Dec. 31, 1998) (span=25 days)
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
-40
-20
0
20
40
MaximumMinimum
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0.0
2.5
5.0
7.5
10.0
Environmental Parameter Std. Dev. Median Mean95% Confidence Interval (Mean)
Daily maximum temperature (degrees Celsius) -30.9 to 34.5 13.2 10.7 8.7 (8.2 , 9.2)
Daily minimum temperature (degrees Celsius) -37.8 to 18.6 11.8 0.5 -1.3 (-1.8 , -0.8)
Daily precipitation (millimetres) 0 to 63.4 4.1 0 1.3 (1.1 , 1.5)
Range
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 35 of 61
Figure 7: Comparing daily maximum temperature and daily mean raw water turbidity (a) Rossdale plant
(b) E.L. Smith plant
Figure 8: Comparing daily precipitation and daily mean raw water turbidity (a) Rossdale plant
(b) E.L. Smith plant
mm and
NTU
°C and NTU
°C and NTU
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98-50
0
50
100
150
200 Raw.water.TBMax.temp
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98-50
0
50
100
150
200 Raw.water.TBMax.temp
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0
50
100
150
200 Raw.water.TBPrecipitation
1/01/93 1/01/94 1/01/95 1/01/96 12/31/96 12/31/97 12/31/98
0
50
100
150
200 Raw.water.TBPrecipitation
mm and
NTU
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 36 of 61
4.1 c) Socio-economic data Average annual household incomes reported in 1995 are shown in Figure 9.
Figure 9: Distribution of average annual household incomes per postal code in Edmonton, 1995
4.1 d) Health outcome data
To ensure that all individuals could be linked to water quality values up to 40 days prior their
date of illness, February 10 th 1993 was the first service date considered for analysis, and December 31,
1998 was the last. Detailed profiles of each data source are provided in Figures 10a to 10d. The
majority of cases were captured by utilizing the physician-office data from the AHCIPP database.
Although long-term care centres also provide regular treatment to individuals suffering from persistent
mental illness and physical disabilities, the majority of patients (70%) captured in this database were
greater than 65 years of age. In contrast, only 10% of selected cases in the emergency room and
physician-visit billing data sources were greater than 65 years.
The distribution of cases by the most responsible ICD-9 code is also provided. For
comparative purposes, the same ICD-9 codes are presented for each data source, and represent the
majority of what was observed in the respective databases.
The seasonal distribution of cases on a bi-weekly basis was also apparent, with a higher
incidence of cases observed during the spring and early summer months. More cases were also
admitted to the hospital at the beginning rather than during the work week. In contrast, more cases
sought emergency room services during the weekend.
- > $80,000 - $65,000 - $80,000 - $50,000-$65,000 - $35,000-$50,000
- $20,000-$35,000 - < $20,000
-113.7 -113.6 -113.5 -113.4 -113.3
LONGITUDE
53.4
53.5
53.6
53.7
LA
TIT
UD
E
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 37 of 61
Figure 10a: Data Profile (February 10, 1993 to December 31, 1998) : Hospital Admissions (CIHI data source)
(i) Distribution of cases by age group and water service area
(ii) Number of cases per 14-day interval (seasonal distribution) (iii) Proportion of cases by most responsible ICD-9 code (iv) Proportion of cases by day of week
Rossdale E.L. Smith Mixed Zone
2 to 18 302 (24.5%) 140 (27.6%) 359 (33.1%)
> 18 to 65 548 (44.4%) 214 (42.2%) 443 (40.9%)
> 65 383 (31.1%) 153 (30.2%) 282 (26.0%)
Total Cases per Water Service Area
1,233 (100%) 507 (100%) 1,084 (100%)
Water Service Area
Age Group (yrs)
0
20
40
60
80
100
001 002 003 004 005 006 007 008 009 276 535 558 578 780 783 787 7890
5
10
15
20
25
Sun Mon Tue Wed Thu Fri Sat
Pro
po
rtio
n o
f a
ll C
IHI
ca
ses
(%)
Pro
po
rtio
n o
f all
CIH
I ca
ses
(%)
1993/01/01 1994/01/01 1995/01/01 1996/01/01 1997/01/01 1998/01/01
5
10
15
20
25
30
35
No.
ca
ses
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 38 of 61
Figure 10b: Data Profile (February 10, 1993 to December 31, 1998) : Emergency room-related visits (EMRG data source)
(i) Distribution of cases by age group and water service area
(ii) Number of cases per 14-day interval (seasonal distribution) (iii) Proportion of cases by most responsible ICD-9 code (iv) Proportion of cases by day of week
Rossdale E.L. Smith Mixed Zone
2 to 18 2,079 (31.4%) 1,361 (37.2%) 2,952 (38.8%)
> 18 to 65 3,834 (57.8%) 2,000 (54.7%) 4,068 (53.5%)
> 65 718 (10.8%) 295 (8.1%) 580 (7.6%)
Total Cases per Water Service Area
6,631 (100%) 3,656 (100%) 7,600 (100%)
Water Service Area
Age Group (yrs)
0
20
40
60
80
100
001 002 003 004 005 006 007 008 009 276 535 558 578 780 787 7890
5
10
15
20
25
Sun Mon Tue Wed Thu Fri Sat
Pro
po
rtio
n o
f all
EMR
G c
ase
s (%
)
Pro
po
rtio
n o
f all
EMRG
ca
ses
(%)
1993/01/01 1994/01/01 1995/01/01 1996/01/01 1997/01/01 1998/01/01
60
100
140
180
No.
ca
ses
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 39 of 61
Figure 10c: Data Profile (February 10, 1993 to December 31, 1998) : Physician-office visits (PHYS data source)
(i) Distribution of cases by age group and water service area
(ii) Number of cases per 14-day interval (seasonal distribution) (iii) Proportion of cases by most responsible ICD-9 code (iv) Proportion of cases by day of week
Rossdale E.L. Smith Mixed Zone
2 to 18 20,659 (33.3%) 11,449 (38.4%) 23,366 (36.5%)
> 18 to 65 36,955 (59.5%) 16,369 (54.9%) 32,105 (54.3%)
> 65 4,446 (7.2%) 2,004 (6.7%) 3,708 (6.3%)
Total Cases per Water Service Area
62,060 (100%) 29,822 (100%) 59,179 (100%)
Water Service Area
Age Group (yrs)
0
20
40
60
80
100
001 002 003 004 005 006 007 008 009 276 535 558 578 780 787 789
0
5
10
15
20
25
Sun Mon Tue Wed Thu Fri Sat
Pro
po
rtio
n o
f all
PHY
S c
ase
s (%
)
Pro
po
rtio
n o
f all
PHY
S c
ase
s (%
)
1993/01/01 1994/01/01 1995/01/01 1996/01/01 1997/01/01 1998/01/01
200
600
1000
1400
No.
ca
ses
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 40 of 61
Figure 10d: Data Profile (February 10, 1993 to December 31, 1998) : Long-term care vists (LTC data source)
(i) Distribution of cases by age group and water service area
(ii) Number of cases per 14-day interval (seasonal distribution) (iii) Proportion of cases by most responsible ICD-9 code (iv) Proportion of cases by day of week
Rossdale E.L. Smith Mixed Zone
2 to 18 22 (6.8%) 10 (8.2%) 20 (8.3%)
> 18 to 65 59 (18.3%) 30 (24.6%) 56 (23.3%)
> 65 241 (74.8%) 82 (67.2%) 164 (68.3%)
Total Cases per Water Service Area
322 (100%) 122 (100%) 240 (100%)
Water Service Area
Age Group (yrs)
0
20
40
60
80
100
001 002 003 004 005 006 007 008 009 276 535 558 578 780 787 7890
5
10
15
20
25
Sun Mon Tue Wed Thu Fri Sat
Pro
po
rtio
n o
f all
LTC
ca
ses
(%)
Pro
po
rtio
n o
f all
LTC
ca
ses
(%)
1993/01/01 1994/01/01 1995/01/01 1996/01/01 1997/01/01 1998/01/01
0
5
10
15
20
No
. ca
ses
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 41 of 61
4.2 Statistical Analyses 4.2 a) Multivariate logistic regression
As described in section 3.2, multivariate logistic regression analysis was conducted to
determine if the risk of gastroenteritis varied for residents of different water service areas. The final
model derived using the generalised linear model (GLM) was :
(refer to Table 5 for a complete description of variable names)
As time was both a component of the seasonal parameter and of the categorical source variable
(SOURCE), the impact of water source was assessed by calculating the relative change after
December 10, 1997 in the risk of gastroenteritis between Rossdale and E.L. Smith serviced residents.
Presented in Table 10 are the results of this comparison, carried out using appropriate contrasts within
the final logistic regression model for each health outcome data set. The odds ratios equate to the
relative change in risk among service areas after Dec 10 ’97. For example, the “risk” in hospitalisation
for gastroenteritis among Rossdale serviced residents in comparison to E.L. Smith serviced residents
fell by a magnitude of 0.18 times after December 10, 1997 (Table 10).
Table 10: Multivariate Logistic Regression Results: Comparisons Among Service Areas
Comparison Parameter
Estimate P-value Odds Ratio
Hospital Admissions (all age groups) (< Dec ‘97): Rossdale \ E.L. Smith vs.
0.1669 0.0557 1.18
(≥ Dec ’97): Rossdale \ E.L. Smith
Emergency Room Visits (all age groups) (< Dec ‘97): Rossdale \ E.L. Smith vs.
0.0956 0.0026 1.10
(≥ Dec ’97) Rossdale \ E.L. Smith
Physician Visits (all age groups) (< Dec ‘97): Rossdale \ E.L. Smith vs.
-0.0147 0.5544 0.99
(≥ Dec ’97): Rossdale \ E.L. Smith
Long-term Care (≥ 65 year olds) (< Dec ‘97): Rossdale \ E.L. Smith vs.
0.1973 0.3145 1.22
(≥ Dec ’97): Rossdale \ E.L. Smith
The results of Table 10 suggest a small lowering in risk of gastroenteritis among Rossdale
residents (in comparison to E.L. Smith serviced residents) after Dec 10 ’97. Statistically significant (P <
0.10) relative “risk” reductions were noted among hospitalisations and emergency room visits.
Logit (case/control) = SOURCE + INCOME + AGEGROUP + SPLINE1st 2 months + … + SPLINE last 2 months
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 42 of 61
Based on the model above, the following spatial model was determined using generalised
additive modeling (GAM):
(refer to Table 5 for a complete description of variable names)
Figure 11 shows the distribution of centroid points associated with all Edmonton postal codes
and their assigned water source.
Figure 11: Spatial distribution of postal codes within Edmonton and corresponding water
service areas
Odds ratios corresponding to each longitude and latitude combination for each captured postal
code were determined, both before and after December 10, 1997. For illustrative purposes, an odds
ratio of 1.2 for each spatial location represents a 20% increase in the likelihood of illness associated
with that centroid point, compared to the predicted probability associated with the mean location effect,
after adjusting for other parameters in the model. Results for each data source are presented in
Figures 12a to 12d. Spatially, there does not appear to be an obvious association between the risk of
gastroenteritis and water supply area after controlling for other important risk factors.
Logit (case/control) = loess (LONGITUDE, LATITUDE, span=0.2) + DEC1097 + INCOME + AGEGROUP + loess (Seasonal parameter, span=220 days)
Rossdale w.s.a
E.L. Smith w.s.a.
Mixed w.s.a.
-113.7 -113.6 -113.5 -113.4 -113.3LONGITUDE
53.4
53.5
53.6
53.7
LATI
TUD
E
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 43 of 61
Figure 12a: Spatial distribution of disease risks within the city of Edmonton between 1993-1998: CIHI hospitalisation data source, excluding infants (less than 2 year-olds)
(i) Prior to December 10, 1997
(ii) After December 10, 1997
< 1.0 1.0 – 1.1 1.1 – 1.2 1.2 – 1.3 > 1.3
Odds Ratios
-113.7 -113.6 -113.5 -113.4 -113.3
longitude
53.4
53.5
53.6
53.7
lati
tud
e
-113.7 -113.6 -113.5 -113.4 -113.3
longitude
53.4
53.5
53.6
53.7
latit
ude
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 44 of 61
Figure 12b: Spatial distribution of disease risks within the city of Edmonton between 1993-1998: Emergency room visit data source, excluding infants (less than 2 year-olds)
(i) Prior to December 10, 1997
(ii) After December 10, 1997
< 1.0 1.0 – 1.1 1.1 – 1.2 1.2 – 1.3 > 1.3
Odds Ratios
-113.7 -113.6 -113.5 -113.4 -113.3
longitude
53.4
53.5
53.6
53.7
lati
tud
e
-113.7 -113.6 -113.5 -113.4 -113.3
longitude
53.4
53.5
53.6
53.7
lati
tud
e
Investigating the relationship between drinking water and gastroenteritis: Edmonton, 1993-1998 November 29th, 2002
Page 45 of 61
Figure 12c: Spatial distribution of disease risks within the city of Edmonton between 1993-1998: Physician-office billing data source (randomised subset),
excluding infants (less than 2 year-olds) (ii) Prior to December 10, 1997
(ii) After December 10, 1997
< 1.0 1.0 – 1.1 1.1 – 1.2 1.2 – 1.3 > 1.3
Odds Ratios
-113.7 -113.6 -113.5 -113.4 -113.3
longitude
53.4
53.5
53.6
53.7
lati
tud
e
-113.7 -113.6 -113.5 -113.4 -113.3
longitude
53.4
53.5
53.6
53.7
latit
ude
