Association of vitamin D status with socio-demographic factors in Calgary, Alberta: an ecological study using Census Canada data

Table 3 Estimates from the population-averaged GEE model investigating associations with vitamin D level

Parameter	Estimate	Standard error	P-value	Overall p-value
Intercept	64.5883	2.4201	<.0001	<.0001
Age (years)				<.0001
age_RCS_lin	−0.2738	0.0422	<.0001
age_RCS_S1	0.0015	0.0001	<.0001
age_RCS_S2	−0.0030	0.0004	<.0001
age_RCS_S3	0.0008	0.0004	0.0823
Median household income ($CDN 10000)				<.0001
income_RCS_lin	−0.4078	0.2350	0.0826
income_RCS_S1	0.0543	0.0263	0.0392
income_RCS_S2	−0.1270	0.0793	0.1092
income_RCS_S3	0.0824	0.0855	0.3352
Percentage of immigrants				<.0001
percentimmi__RCS_lin	−7.6190	9.4844	0.4218
percentimmi__RCS_S1	−172.823	567.4589	0.7607
percentimmi__RCS_S2	−1122.79	1547.330	0.4681
percentimmi__RCS_S3	3152.879	1511.398	0.0370
Percentage of aboriginal people				<.0001
percentabor__RCS_lin	−68.5534	15.3580	<.0001
percentabor__RCS_S1	13868.36	5311.648	0.0090
Percentage of subjects with some post-secondary education				<.0001
percentuniv_RCS_lin	13.6596	4.2690	0.0014
percentuniv_RCS_S1	237.8126	69.0070	0.0006
percentuniv_RCS_S2	−842.990	263.7487	0.0014
percentuniv_RCS_S3	1090.294	509.4453	0.0323
Gender				<.0001
Female	7.4674	0.1930	<.0001
Male	0.0000	0.0000	.
Month of vitamin D testing				<.0001
December	−1.3870	0.5024	0.0058
November	0.1357	0.4583	0.7672
October	−1.3138	0.4593	0.0042
September	−0.1319	0.4590	0.7738
August	4.7383	0.4252	<.0001
July	3.7308	0.4142	<.0001
June	0.5034	0.3959	0.2035
May	3.5073	0.4330	<.0001
April	0.6403	0.4129	0.1209
March	−3.6969	0.4045	<.0001
February	0.4483	0.4108	0.2751
January	0.0000	0.0000	.

Note: Age, median household income, percentage of immigrants, and percentage of subjects with some post-secondary education were coded using restricted cubic spline (RCS) functions with five knots located at the 5th, 25th, 50th, 75th, and 95th percentiles of their distribution, and percentage of aboriginal people was coded using the 5th, 50th and 95th percentiles of its distribution. The variables listed underneath each of the continuous variables are their corresponding spline variables (e.g., age_RCS_lin, age_RCS_S1, age_RCS_S2, and age_RCS_S3 are the 4 spline variables of age).

ISSN: 1471-2458