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Posted as supplied by authors.

Web table A: Chlamydia prevalence, uptake of screening, coverage, area deprivation and ethnic mix by practice

Practice number	N¹	n²	Coverage, %³	Uptake, %⁴	Prevalence, % (95% CI)⁵	Deprivation score⁶	Ethnic mix, %⁷
1	345	38	83.4	16.4	0.0 (0.0, 0.9)⁸	63.6	68.3
2	60	13	79.5	28.1	0.0 (0.0, 4.9)⁸	42.7	25.5
3	746	130	73.2	23.3	1.7 (0.4, 7.1)	32.3	3.7
4	573	117	81.4	25.1	2.6 (0.8, 8.3)	36.0	4.5
5	381	53	69.7	19.9	3.1 (0.8, 11.8)	63.4	65.1
6	477	117	85.2	28.5	3.3 (1.2, 8.5)	15.2	1.2
7	752	237	63.1	52.0	3.4 (1.6, 6.9)	10.6	8.8
8	330	80	86.3	28.6	3.8 (1.2, 11.2)	36.4	9.7
9	338	116	86.2	39.8	3.8 (1.7, 8.3)	10.1	1.4
10	1308	249	49.6	41.3	4.1 (1.8, 9.0)	35.2	21.6
11	535	190	85.5	41.3	4.5 (2.2, 8.8)	7.7	1.7
12	1009	266	64.2	39.0	4.8 (2.8, 8.2)	28.1	10.6
13	226	45	76.9	25.5	4.9 (1.2, 17.9)	44.2	9.9
14	852	165	77.2	24.1	5.0 (2.3, 10.5)	38.1	7.3
15	402	129	84.8	37.4	5.2 (2.3, 11.4)	32.3	3.7
16	553	195	79.9	43.3	5.3 (2.8, 9.9)	27.3	3.8
17	209	56	83.3	32.2	5.5 (1.7, 15.8)	30.3	14.2
18	552	137	86.6	27.9	6.5 (3.4, 12.1)	38.8	5.8
19	1321	274	72.8	30.4	7.2 (4.2, 12.2)	15.6	2.0
20	689	188	78.2	33.1	7.6 (4.5, 12.6)	26.5	7.4
21	963	194	69.6	29.0	8.5 (5.3, 13.3)	59.1	67.7
22	718	197	83.4	34.0	8.5 (4.7, 14.7)	47.0	7.5
23	290	58	69.4	27.8	9.0 (3.7, 20.0)	40.0	40.8
24	265	70	83.6	31.5	9.9 (4.8, 19.5)	45.9	9.7
25	444	74	77.2	21.3	11.2 (5.1, 23.1)	38.4	35.6
26	340	76	80.6	27.0	12.3 (6.5, 22.1)	56.2	4.0
27	641	145	84.4	27.7	12.4 (7.2, 20.6)	30.6	5.5
Combined	15319	3609	75.6	31.5	5.9 (5.0, 7.0)	34.2	8.3

Legend:

1 � Total number of 16 to 24 year olds in each practice, including 4,074 patients confirmed non-resident at their registered address

2 � Number responding in each practice

3 � Proportion confirmed to have received a screening invitation, weighted to take sampling probability into account.

4 � Proportion of those receiving an invitation that returned a sample, weighted to take sampling probability into account,

5 � Prevalence estimates weighted to take sampling probability into account. Random effects meta-analysis of the log odds of prevalence was used to investigate heterogeneity of prevalence between practices (p=0.052). The I² statistic suggested that 34% of variability was not due to random error.

6 � Index of Multiple Deprivations 2000 score. Average score for ward of residence of sampled 16-24 year patients in each practice, weighted for sampling probability.

7 � Proportion of practice population from non-white ethnic groups: 2001 Census. Average score for ward of residence of sampled 16-24 year patients in each practice, weighted for sampling probability.

8 � Exact 95% confidence interval. Does not account for sampling probability.

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Posted as supplied by author.

Web table B: Practice level factors associated with coverage and uptake of postal screening

Variable	�	Coverage, OR (95% CI)		�	Uptake, OR (95% CI)		�
�	�	Crude¹	Adjusted²	P	Crude¹	Adjusted²	P²
Deprivation score	Per 10 point increase	0.98 (0.88, 1.10)	1.13 (0.98, 1.29)	0.083	0.86 (0.80, 0.93)	0.88 (0.80, 0.96)	0.004
Proportion non-white	Per 10% increase	0.93 (0.87, 0.99)	0.87 (0.81, 0.94)	0.001	0.92 (0.87, 0.97)	0.98 (0.92, 1.05)	0.708

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Legend:

Logistic regression models include 15,319 men and women aged 16 to 24 years in 27 general practices

1 � Adjusted for sampling probability using inverse probability weights and clustering by practice using robust standard errors.

2 � Additionally adjusted for variables in table plus age and sex. P value refers to adjusted model.

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Posted as supplied by author.

Web table C: Associations between prevalence and individual and practice level covariates. Men

Men		N¹	Positive	Prevalence,² % (95% CI)	Odds ratio (95% CI)
					Crude²	Adjusted³	P⁴
All		1437	63	5.1 (4.0, 6.3)
Individual level factors
Age in years	16-19	679	22	3.5 (2.3, 5.2)	1 (reference)	1 (reference)	0.010
	20-24	758	41	6.7 (5.0, 8.8)	2.0 (1.1, 3.5)	2.1 (1.2, 3.7)
Marital status	Single	1315	58	5.1 (4.0, 6.5)	1 (reference)	1 (reference)	0.706
	Married	119	5	5.2 (2.2, 12.2)	1.0 (0.3, 2.9)	0.8 (0.3, 2.2)
	Divorced	3	0	..	..	..
Ethnic group	White	1244	55	5.3 (4.1, 6.5)	1 (reference)	1 (reference)	0.322
	Black	78	8	11.1 (5.9, 20.0)	2.0 (1.0, 4.6)	1.6 (0.6, 3.9)
	Indian	70	0	..	..	..	..
	Chinese	5	0	..	..	..	..
	Other	40	0	..	..	..	..
Practice level factors
Deprivation score in practice population (per 10 point increase)				..	1.1 (1.0, 1.2)	1.1 (0.9, 1.4)	0.427
Proportion non-white in practice population (per 10% increase)				..	1.0 (0.9, 1.2)	1.1 (0.9, 1.3)	0.536
Uptake rate in practice (per 10% increase)				..	0.9 (0.7, 1.1)	0.9 (0.6, 1.2)	0.411

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Legend:

1 � Logistic regression model restricted to 1437 men aged 16 to 24 years with complete data for all variables

2 � Adjusted for weighting and clustering using inverse probability weights and robust standard errors

3 � Adjusted for weighting, clustering and other variables in table

4 � Wald test for heterogeneity between categories: refers to adjusted model.

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Posted as supplied by author.

Web table D: Associations between prevalence and individual and practice level covariates. Women

Women		N¹	Positive	Prevalence,² % (95% CI)	Odds ratio (95% CI)
					Crude²	Adjusted³	P⁴
All		2083	128	6.2 (5.2, 7.8)
Individual level factors
Age in years	16-19	881	54	6.0 (4.6, 8.4)	1 (reference)	1 (reference)	0.367
	20-24	1202	74	6.2 (4.9, 8.4)	1.0 (0.7, 1.6)	1.2 (0.8, 2.0)
Marital status	Single	1646	116	7.0 (5.9, 9.2)	1 (reference)	1 (reference)	0.007
	Married	426	12	2.6 (1.5, 4.8)	0.3 (0.2, 0.8)	0.3 (0.1, 0.7)
	Divorced	11	0	..	..	..
Ethnic group	White	1778	104	5.9 (4.9, 7.7)	1 (reference)	1 (reference)	0.573
	Black	164	18	9.5 (6.1, 21.0)	1.7 (0.7, 4.3)	2.0 (0.7, 5.1)
	Indian	73	2	3.8 (1.0, 21.4)	0.6 (0.1, 4.0)	0.90 (0.1, 9.8)
	Chinese	11	2	17.9 (4.5, 56.8)	3.5 (0.6, 22.0)	3.5 (0.5, 24.2)
	Other	57	2	4.6 (1.2, 17.3)	0.8 (0.2, 3.4)	1.0 (0.2, 4.8)
Practice level factors
Deprivation score in practice population (per 10 point increase)				..	1.1 (0.9, 1.3)	1.2 (0.9, 1.5)	0.169
Proportion non-white in practice population (per 10% increase)				..	1.0 (0.8, 1.2)	0.8 (0.6, 1.1)	0.132
Uptake rate in practice (per 10% increase)				..	0.8 (0.6, 1.1)	0.8 (0.6, 1.1)	0.412