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Table 2 Annual proportion tested for syphilis among HIV-positive participants in the OHTN Cohort Study, 2000-2009

From: Patterns of syphilis testing in a large cohort of HIV patients in Ontario, Canada, 2000–2009

 

n observation

% tested

Unadjusted ratio of proportions (95%CI)

Adjusted ratio of proportions (95%CI)

Calendar year

    

  2000

1605

2.7

  

  2001

1524

6.0

  

  2002

1566

7.7

  

  2003

1507

10.2

  

  2004

1627

16.8

  

  2005

1616

32.6

  

  2006

1580

43.3

  

  2007

1592

43.6

  

  2008

2767

42.3

  

  2009

3324

54.6

  

  Each additional calendar year (a)

    

  2003 cf 2002

  

1.59 (1.54, 1.69)

1.53 (1.48, 1.58)

  2005 cf 2004

  

1.39 (1.36, 1.42)

1.32 (1.30, 1.35)

  2009 cf 2008

  

1.05 (1.03, 1.08)

0.98 (0.96, 1.01)

STI risk status

    

  MSM

12,912

31.7

1.39 (1.27, 1.53)

1.20 (1.11, 1.30)

  Non-MSM males

2,877

22.6

Referent

Referent

  Females

2,642

26.2

1.17 (1.03, 1.32)

1.03 (0.93, 1.14)

  Unknown

277

47.3

  

Region

    

  Toronto

10,014

31.7

1.19 (1.11, 1.27)

0.83 (0.78, 0.88)

  Ottawa

2,527

26.9

0.89 (0.80, 0.99)

0.70 (0.64, 0.77)

  Other

6,167

27.8

Referent

Referent

Age (b)

    

  <30 years

576

41.8

Referent

Referent

  30+ years

18,132

29.4

0.72 (0.64, 0.81)

0.89 (0.81, 0.97)

Race/ethnicity

    

  White

13,322

28.6

Referent

 

  Black/African

1,463

28.9

1.01 (0.90, 1.13)

 

  Aboriginal

1,092

32.6

1.13 (1.00, 1.27)

 

  Other

2,363

33.4

1.17 (1.08, 1.27)

 

  Unknown

468

42.5

  

Nature of care provided at OCS clinic

    

  Primary

4,242

44.5

1.74 (1.64, 1.84)

1.34 (1.27, 1.41)

  Tertiary

14,466

25.5

Referent

Referent

Diagnosed with HIV in current or preceeding year (b)

    

  No

18,330

29.1

Referent

Referent

  Yes

378

63.5

1.88 (1.73, 2.04)

1.29 (1.19, 1.41)

Syphilis testing in previous year (b)

    

  Not tested

13,995

18.3

Referent

Referent

  Non-reactive

3,755

62.0

4.90 (4.69, 5.12)

1.75 (1.66, 1.84)

  Reactive

888

73.6

5.45 (5.18, 5.73)

2.01 (1.89, 2.15)

Test result undetermined (c)

70

35.7

  

Initiated HIV antiretoviral treatment (b)

    

  Yes

17,620

29.2

0.75 (0.68, 0.83)

0.92 (0.86, 0.99)

  No

1,088

38.6

Referent

Referent

Number of routine HIV tests in year (b, d)

    

  None

451

4.2

0.18 (0.11, 0.29)

0.23 (0.14, 0.40)

  One

1186

23.4

Referent

Referent

  Two or more

17071

30.9

1.32 (1.20, 1.45)

1.27 (1.16, 1.40)

  1. Each observation represents a single calendar year of active follow-up. We calculated ratios of proportions using Poisson regression within a generalized estimating equation framework to account for repeated observations. The within-subject correlation coefficient was 0.40 in an intercept-only model. The adjusted model included all covariates shown except ethnicity.
  2. (a) There were statistically significant quadratic effects of calendar year. Beta coefficients for the linear and quadratic terms were 1.89 (95%CI 1.79, 2.01) and 0.966 (95%CI 0.962, 0.971) in the unadjusted model, and 1.84 (95%CI 1.74, 1.94) and 0.964 (0.960, 0.969) in the adjusted model, respectively.
  3. (b) Time updated each calendar year.
  4. (c) Reasons for unavailable test results in the preceding year included that the specimens were not tested or results were pending.
  5. (d) The number of routine HIV tests in the year was defined as the maximum of the total number of HIV viral load or the total number of CD4 cell count tests in a calendar year, whichever was greater. It is a proxy measure of the frequency of contact with HIV care.