Upsurge of chlamydial reinfection in a large Canadian City: an indication of suboptimal Chlamydia screening practices?
Genereux, Melissa ; Leclerc, Pascale ; Bedard, Lucie 等
Sexually transmitted infections (STIs), particularly chlamydia,
pose a serious threat to the health of Canadians and strain health care
resources. (1-3) Chlamydial reinfections (CR) may significantly add to
the existing burden. Indeed, relative to a single infection, recurrent
Chlamydia infections have been demonstrated to increase the risk of
ectopic pregnancy, pelvic disease (4) and female infertility. (5,6)
Moreover, CR may be responsible for maintaining endemic rates of
chlamydial infection. Finally, CR, a marker of persistent risk-taking,
reflects the effectiveness of the STI prevention and management and
therefore constitutes a useful monitoring indicator.
Updated in 2008, the Canadian Guidelines on STI are a valuable
resource for clinical and public health professionals. (7) Several
recommendations have been proposed to prevent CR, including 1) more
intensive screening of young males, thought to be hidden reservoirs for
reinfection of partners, and 2) repeat screening of all individuals with
genital chlamydia six months post-treatment. (7,8)
Although CR is routinely observed in clinical practice, we know
little about its frequency and distribution in Canada. Our knowledge
lags behind in comparison with the United States, where several studies
on CR have been conducted over the past years. (9-23) We have found only
one published Canadian study that reported a high (i.e., 10%) and
increasing CR rate among persons 15-50 years living in the greater
Vancouver area passively followed for a 14-year period (1989-2003). (24)
Given the scarcity of data on this silent epidemic in Canada, our goal
in the present study was to determine the extent and main predictors of
CR in a large Canadian city using a population database of individuals
diagnosed at least once with chlamydial infection. We were particularly
interested in examining the temporal trends of CR to stimulate critical
reflection about current STI prevention practices.
METHODS
Settings
The study was conducted on the Island of Montreal from 1988 to
2007. The 2006 census enumerated 1.9 million inhabitants in Montreal. In
2003, the island's health services were divided into 12 Health and
Social Services Centres responsible for promoting health and well-being
within a given territory. To assess the intra-urban spatial variation of
CR, we merged the 12 Centres into four geographic sectors --South
Central, North Central, East and West (see Figure 1).
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
For the past two decades in the province of Quebec, it has been
mandatory for laboratories and physicians to report all cases of
chlamydial infection to regional public health departments (PHD). Data
were extracted from the regional Maladies a declaration obligatoire
(MADO) registry. The registry stores data on all reportable diseases and
minimally provides, for each episode reported, a unique identification
number (i.e., personal identifier based on name, birth date and
residential address) as well as the socio-demographic characteristics
and residential address of the individual affected, the diagnosis and
report date.
Study population
We performed a longitudinal analysis of all persons >10 years
old (at the time of their first diagnosis) with at least one
laboratory-confirmed chlamydial infection reported to the PHD from
October 1988 (date of implementation of the reportable disease database)
to the end of 2007. Entry into the study was defined as an Island of
Montreal resident's date of first notification of chlamydial
infection during the study period. The sample included 44,580
individuals.
Measures
CR was defined as a chlamydial infection reported 60 to 730 days
(two years) following a first infection for the same individual during
the study period. Only the first reinfection, in case of multiple
reinfections, was considered. For each subject, passive follow-up ended
at the first of the following events: 1) reinfection, 2) December 31,
2007 (end of study period), or 3) end of the two-year period since
entry. As clearly demonstrated elsewhere, most repeated chlamydial
infections, particularly those diagnosed several weeks after initial
diagnosis, are reinfections (i.e., new incident infections) rather than
persistence without treatment or with treatment failure. (25) However,
since many recent studies observed that most CR occur within two years,
follow-up was limited to two years after initial infection to increase
the number of CR identified while reducing the probability of loss to
follow-up due to death or emi gration. (17,22,23,25)
The following baseline characteristics were investigated as
potential predictors of CR: sex, age, year, geographic sector, and
history of other notifiable diseases including other STIs, enteric
infections and vaccine-preventable infections (see Table 1 for details
about infections included in each category). Continuous variables (age
and year) were categorized using clinically relevant cut-offs. We
created six age groups: 10-14, 15-19, 20-24, 25-29, 30-39, and [greater
than or equal to] 40 years. Dates of initial chlamydial infection were
categorized as follows: 1988-1995 and 1996-2007. This cut-off point was
chosen based on the increasing trend in observed STI cases since the
mid-1990s in Canada. (1-3,26) For each individual, the geographic sector
(North Central, South Central, East, or West) was determined according
to the residential address provided at first notification. History of
notifiable diseases was defined as having had a disease reported under
Quebec's public Health Act prior to the first episode of Chlamydia
infection reported during the study period.
Analysis
First, we examined temporal trends in CR by computing annual
incidence density (i.e., number of CR per 100 person-years) for the full
sample (n=44,580). Since preliminary analyses showed that about a third
of residential addresses were missing, we compared baseline
characteristics of persons with and without residential information.
Subsequent analyses were restricted to persons with residential
addresses (n=30,520). Survival functions of time to reinfection were
estimated using the Kaplan-Meier method. Log-rank tests were used to
compare reinfection curves according to baseline characteristic. The
proportional hazards assumption was verified for each baseline
characteristic using graphical log-minus-log and Schoenfeld weighted
residuals tests. Survival analyses were stratified by age (<25 vs.
[greater than or equal to] 25 years), as the proportional hazards
assumption was not valid between these two age groups. Stratification
was also supported by the clinical relevance of addressing the issue of
CR among younger and older persons separately. Then, Cox proportional
hazards regression was used to model the time to reinfection, using
baseline characteristics as potential predictor variables. Only
variables significantly associated with CR (p<0.05) were retained in
final models. We decided to transform the "geographic sector"
variable into a time-dependent variable given that the proportional
hazards assumption was not met for this variable (i.e., hazard ratio not
constant over time). Hence, we attempted to model the interaction of
geographic sector with time using clinically meaningful time intervals
(<6 vs. [greater than or equal to] 6 months after baseline
infection). Final multivariate models were used to estimate adjusted
hazard ratios (AHR) and corresponding 95% confidence intervals (CI) for
relationship between predictor variables and time to reinfection. All
analyses were conducted using SPSS version 12.0 (SPSS Inc., Chicago,
Illinois).
RESULTS
In our study, 2,837 (6.4%) persons were reinfected with Chlamydia
within two years of first infection. From 1989 to 1994 in Montreal, the
annual counts and incidence density of CR remained low and then rose
sharply (Figure 2).
CR for individuals with missing addresses did not differ from the
others. Both groups had an overall incidence density of 3.5/100
person-years. However, there were more women and older persons among
individuals with missing addresses (Table 1).
Univariate survival analyses showed that among persons <25
years, reinfection was more likely among females, adolescents (10-14
years), people initially infected after 1995, those living outside the
South sector, and those with a history of notifiable enteric or
vaccine-preventable infections (Table 2). By contrast, for people
[greater than or equal to] 25 years, risk of CR was higher among those
whose first chlamydial infection occurred post-1995 or who had a history
of other notifiable STIs.
[FIGURE 3 OMITTED]
Table 3 displays Cox multivariate regression models for persons
<25 years and for those [greater than or equal to] 25 years. Among
people <25 years, independent risk factors for CR included being
female, <20 years old, and having a first infection after 1995.
Furthermore, the association between CR and geographic location
indicated that residing in the South Central sector was deleterious in
the first six months following initial infection but protective after
this period. By contrast, only two factors positively predicted CR among
persons [greater than or equal to] 25 years: a history of other STIs,
and first infection after 1995.
DISCUSSION
Our study complements others by demonstrating that some predictors
are specific to younger or older individuals. This finding is important
as it emphasizes the need to adapt preventive strategies to
socio-demographic factors such as sex, age and place of residence. Our
findings also provoke critical examination of the relevance of currently
proposed recommendations in the Canadian Guidelines on STI, and the
time- and space-dependent contextual conditions that may shape the risk
of CR.
The two-year CR rate of 6.4% observed among Montreal residents was
slightly inferior to the 10% rate found in Vancouver. (24) The higher
rate observed in Vancouver might be explained by a longer follow-up
period (up to 14 years), which allowed more time for reinfection.
Indeed, in our study, extending follow-up to the complete study period
(1988-2007) would result in a 9.9% CR rate (Figure 3).
Our estimate of the median time between the initial and the
following chlamydial infection (nine months) is consistent with the
existing literature. Indeed, median time estimates across studies have
continually been superior to six months. (22,23,27) If all physicians
were to implement Canadian guidelines recommending repeat testing of
individuals with chlamydial infection six months post-treatment, (7)
over half of reinfected cases would not be diagnosed and reported.
As observed by other researchers, we also found that young females
were at increased risk for reinfection. (9,13,15,18) These results
support the Canadian recommendation to increase screening of young
males, the hidden reservoir; this specific measure is regarded as a
promising strategy to reduce infections and reinfections among young
females. (28)
Similar to Vancouver, we observed a significant increase in
reinfections in 1996-2007 versus 1988-1995 that coincides with an
increase in STIs. (24,26) Several factors may explain the simultaneous
upsurge of chlamydial infections and reinfections, including changes in
sexual risk behaviour, diagnostic test and reportable disease
surveillance. (29-32) Innovations in HIV therapy in the mid-1990s led to
treatment optimism and reduced risk awareness. (7) Moreover, more
acceptable, more sensitive and less specific screening tests (i.e.,
nucleic acid amplification tests) (33) became widely available in the
last decade in Montreal. Alternatively, the increase in CR may be due to
causes specific to reinfection, such as the arrested immunity hypothesis
which posits that early treatment of Chlamydia interferes with the
development of protective immune response. (34)
Contrary to expectations, hospital-diagnosed reproductive sequelae,
such as pelvic inflammatory disease and ectopic pregnancy, have steadily
declined since the mid-90s in Montreal (results not shown) and
elsewhere. (30,31,35,36) The fact that an increase in reinfections did
not parallel trends in associated complications suggests that frequent
infections are not as damageable to reproductive health as long-lasting
untreated infections. If this hypothesis were true, intensive screening
of CR, rather than prevention, would be a first priority.
Our study is subject to limitations. First, one third of the full
sample was missing residential address and was excluded from survival
analyses; however CR rates were calculated using data from the full
sample. The remaining individuals differed from those excluded with
regard to age, sex, and possibly other unmeasured factors. Second, our
sample is only representative of the population using health care
services. Thus, our estimated rates may only represent the "tip of
the iceberg". Third, persons were only passively followed, which
precluded being informed of their vital and migration statuses.
Subsequent chlamydial infections diagnosed among persons who had moved
outside of Montreal may have resulted in an underestimation of CR rates.
Similarly, we were only able to investigate the influence of residential
location at baseline, although it may have changed over time. Fourth,
our measurement of CR (i.e., second episode >60 days following
initial episode) may, in some instances, reflect persistence of previous
infection left untreated or ineffectively treated rather than true
reinfection. Finally, our choice of predictors was limited to those
available in the MADO registry.
Our results support frequent targeted re-screenings during the
first year following initial Chlamydia infection, with particular focus
on young women. We question the current recommendation of a single
repeat screening six months post-treatment in light of our finding that
most reinfections may occur later than six months following initial
infection.
Conflict of Interest: None to declare.
REFERENCES
(1.) Public Health Agency of Canada. Reported cases and rates of
genital chlamydia by age group and sex, 1991 to 2007. Available at:
http://www.phac-aspc.gc.ca/stdmts/sti-its_tab/chlamydial99l-07- eng.php
(Accessed February 19, 2009).
(2.) Weir E. Upsurge of genital Chlamydia trachomatis infection.
CMAJ2004;171(8):855.
(3.) Public Health Agency of Canada. 2004 Canadian Sexually
Transmitted Infections Surveillance Report. CCDR 2007;33(S1):l-69.
(4.) Hillis SD, Owens LM, Marchbanks PA, Amsterdam LF, MacKenzie
WR. Recurrent chlamydial infections increase the risks of
hospitalization for ectopic pregnancy and pelvic inflammatory disease.
Am J Obstet Gynecol 1997;176(l):103-7.
(5.) Grayston JT, Wang SP, Yeh LJ, Kuo CC. Importance of
reinfection in the pathogenesis of trachoma. Rev Infect Dis
1985;7(6):717-25.
(6.) Van Voorhis WC, Barrett LK, Sweeney YT, Kuo CC, Patton DL.
Repeated Chlamydia trachomatis infection of Macasa nemestrina fallopian
tubes produces a Th1-like cytokine response associated with fibrosis and
scarring. Infect Immun 1997;65(6):2175-82.
(7.) Public Health Agency of Canada. Canadian Guidelines on
Sexually Transmitted Infections. January 2008. Available at:
http://www.phac-aspc.gc.ca/stdmts/sti-its/guide-lignesdir-eng.php
(Accessed September 12, 2009).
(8.) MacDonald N, Wong T. Canadian guidelines on sexually
transmitted infections, 2006. CMAJ 2007;176(2):175-76.
(9.) Hillis SD, Nakashima A, Marchbanks PA, Addiss DG, Davis JP.
Risk factors for recurrent Chlamydia trachomatis infections in women. Am
J Obstet Gynecol 1994;170(3):801-6.
(10.) Richey CM, Macaluso M, Hook EW. Determinants of reinfection
with Chlamydia trachomatis. Sex Transm Dis 1999;26(1):4-11.
(11.) Burstein GR, Zenilman JM, Gaydos CA, Diener-West M, Howell
MR, Brathwaite W, Quinn TC. Predictors of repeat Chlamydia trachomatis
infections diagnosed by DNA amplification testing among inner city
females. Sex Transm Infect 2001;77(l):26-32.
(12.) Whittington WL, Kent C, Kissinger P, Oh MK, Fortenberry JD,
Hillis SE, et al. Determinants of persistent and recurrent Chlamydia
trachomatis infection in young women: Results of a multicenter cohort
study. Sex Transm Dis 2001;28(2):117-23.
(13.) Rietmeijer CA, Van Bemmelen R, Judson FN, Douglas JM.
Incidence and repeat infection rates of Chlamydia trachomatis among male
and female patients in a STD clinic: Implications for screening and
rescreening. Sex Transm Dis 2002;29(2):65-72.
(14.) Veldhuijzen IK, Van Bergen JE, Gotz HM, Hoebe CJ, Morre SA,
Richardus JH; PILOT CT Study Group. Reinfections, persistent infections,
and new infections after general population screening for Chlamydia
trachomatis infection in the Netherlands. Sex Transm Dis
2005;32(10):599-604.
(15.) Magnus M, Schillinger JA, Fortenberry JD, Berman SM,
Kissinger P. Partner age not associated with recurrent Chlamydia
trachomatis infection, condom use, or partner treatment and referral
among adolescent women. J Adolesc Health 2006;39(3):396-403.
(16.) Niccolai LM, Hochberg AL, Ethier KA, Lewis JB, Ickovics JR.
Burden of recurrent Chlamydia trachomatis infections in young women:
Further uncovering the hidden epidemic. Arch Pediatr Adolesc Med
2007;161(3):246-51.
(17.) Scott Lamontagne DS, Baster K, Emmett L, Nichols T, Randall
S, McLean L, et al. Incidence and reinfection rates of genital
chlamydial infection among women aged 16-24 years attending general
practice, family planning and genitourinary medicine clinics in England:
A prospective study by the Chlamydia Recall Study Advisory Group. Sex
Transm Infect 2007;83(4):292-303.
(18.) Gaydos CA, Wright C, Wood BJ, Waterfield G, Hobson S, Quinn
TC. Chlamydia trachomatis reinfection rates among female adolescents
seeking rescreening in school-based health centers. Sex Transm Dis
2008;35(3):233-37.
(19.) Joesoef MR, Weinstock HS, Johnson RE. Factors associated with
recurrent chlamydial infection and failure to return for retesting in
young women entering national job training program, 1998-2005. Sex
Transm Dis 2008;35(4):368-71.
(20.) Blythe MJ, Katz BP, Batteiger BE, Ganser JA, Jones RB.
Recurrent genitourinary chlamydial infections in sexually active female
adolescents. J Pediatr 1992;121(3):487-93.
(21.) Anschuetz GL, Beck JN, Asbel L, Goldberg M, Salmon ME, Spain
CV. Determining risk markers for gonorrhea and chlamydial infections and
reinfections among adolescents in public high schools. Sex Transm Dis
2009;36(l):4-8.
(22.) Xu F, Schillinger JA, Markowitz LE, Sternberg MR, Aubin MR,
St Louis ME. Repeat Chlamydia trachomatis infection in women: Analysis
through a surveillance case registry in Washington State, 1993-1998. Am
J Epidemiol 2000;152(12):1164-70.
(23.) Evans C, Das C, Kinghorn G. A retrospective study of
recurrent Chlamydia infection in men and women: Is there a role for
targeted screening for those at risk? Int J STD & AIDS
2009;20(3):188-92.
(24.) Brunham RC, Pourbohloul B, Mak S, White R, Rekart ML. The
unexpected impact of a Chlamydia trachomatis infection control program
on susceptibility to reinfection. J Infect Dis 2005;192(10):1836-44.
(25.) Batteiger BE, Tu W, Ofner S, Van Der Pol B, Stothard DR, Orr
DP, et al. Repeated Chlamydia trachomatis genital infections in
adolescent women. J Infect Dis 2010;201(1):42-51.
(26.) Leclerc P, Tremblay C, Morissette C. Situation
epidemiologique des infections transmissibles sexuellement et par le
sang (ITSS) pour la region de Montreal --2006. Direction de sante
publique de l'Agence de la sante et des services sociaux de
Montreal, 2007.
(27.) Hosenfeld CB, Workowski KA, Berman S, Zaidi A, Dyson J,
Mosure D, et al. Repeat infection with Chlamydia and Gonorrhea among
females: A systematic review of the literature. Sex Transm Dis
2009;36(8):478-89.
(28.) Greer AL, Fisman DJ. Punching above their weight. Males,
reinfection, and the limited success of Chlamydia screening programs.
Sex Transm Dis 2009;36(1):9-10.
(29.) Hagdu A. Issues in Chlamydia trachomatis testing by nucleic
acid amplification test. J Infect Dis 2006;193(9):1335-36.
(30.) Moss NI, Ahrens K, Kent CK, Klausner JD. The decline in
clinical sequelae of genital Chlamydia trachomatis infection supports
current control strategies. J Infect Dis 2006;193(9):1336-38.
(31.) Brunham RC, Pourbohloul B, Mak S, White R, Rekart ML. Reply
to Hagdu and to Moss et al. J Infect Dis 2006;193(9):1338-39.
(32.) Gilbert M, Rekart ML. Recent trends in chlamydia and
gonorrhea in British Columbia. BCMJ 2009;51(10):435.
(33.) Rekart ML, Brunham RC. Epidemiology of chlamydial infection:
Are we losing ground? Sex Transm Infect 2008;84(2):87-91.
(34.) Brunham RC, Rekart ML. The arrested immunity hypothesis and
the epidemiology of chlamydia control. Sex Transm Dis 2008;35(1):53-54.
(35.) Whiteman MK, Kuklina E, Jamieson DJ, Hillis SD, Marchbanks
PA. Inpatient hospitalization for gynecologic disorders in the United
States. Am J Obstet Gynecol 2010;202(6):541.e1-541.e.
(36.) Hoover KW, Tao G, Ken CK. Trends in the diagnosis and
treatment of ectopic pregnancy in the United States. Obstet Gynecol
2010;115(3):495-502.
Received: February 2, 2010
Accepted: May 9, 2010
Melissa Genereux, MD, MSc, FRCPC, [1,2] Pascale Leclerc, MSc, [3]
Lucie Bedard, RN, M Nsc, mph, [3,4] Robert Allard, md, MSc, frcpc [3-5]
Author Affiliations
[1.] Departement des sciences de la sante communautaire, Faculte de
medecine et des sciences de la sante, Universite de Sherbrooke,
Sherbrooke, QC
[2.] Direction de sante publique et de l'evaluation de
l'Agence de la sante et des services sociaux de l'Estrie,
Sherbrooke, QC
[3.] Direction de sante publique de l'Agence de la sante et
des services sociaux de Montreal, Montreal, QC
[4.] Departement de medecine sociale et preventive, Faculte de
medecine, Universite de Montreal, Montreal, QC
[5.] Department of Epidemiology, Biostatistics and Occupational
Health, McGill University, Montreal, QC
Correspondence: Dr. Melissa Genereux, Faculte de medecine et des
sciences de la sante, Universite de Sherbrooke, Departement des sciences
de la sante communautaire, Pavillon Gerald-Lasalle, 3001 12e avenue
Nord, Sherbrooke, QC J1H 5N4, E-mail: melissa.genereux@usherbrooke.ca
Table 1. Baseline and Follow-up Characteristics of Cases with
[greater than or equal to] 1 Chlamydial Infection Reported to
the Regional Public Health Department (n = 44,580), by
Residential Location Status (Available vs. Missing),
Two-year Follow-up, Montreal, 1988-2007
Characteristics Residential Residential
Location Available Location Missing
n (%) n (%)
Baseline
Sex
Female 22,477 (73.6%) 9169 (65.2%)
Male 8043 (26.4%) 4891 (34.8%)
Age (years)
10-14 343 (1.1%) 75 (0.5%)
15-19 8633 (28.3%) 3069 (21.8%)
20-24 10,482 (34.3%) 5223 (37.1%)
25-29 5577 (18.3%) 2726 (19.4%)
30-39 4146 (13.6%) 2173 (15.5%)
[greater than or equal to] 40 1339 (4.4%) 794 (5.6%)
Year
1988-1995 13,844 (45.4%) 2279 (16.2%)
1996-2007 16,676 (54.6%) 11,781 (83.8%)
Geographic sector
South Central 12,210 (40.0%)
North Central 6275 (20.6%)
East 7354 (24.1%)
West 4681 (15.3%)
History of other notifiable
STIs *
Yes 284 (0.9%) 124 (0.9%)
No 30,236 (99.1%) 13,936 (99.1%)
History of notifiable
enteric infections *
Yes 140 (0.5%) 52 (0.4%)
No 30,380 (99.5%) 14,008 (99.6%)
History of notifiable
vaccine-preventable infections *
Yes 43 (0.1%) 12 (0.0%)
No 30,477 (99.9%) 14,048 (99.9%)
Follow-up
Chlamydial reinfection
Yes 1952 (6.4%) 885 (6.3%)
No 28,568 (93.6%) 13,175 (93.7%)
Incidence density of
chlamydial reinfection 3.5 per 100 3.5 per 100
person-years person-years
Median time to chlamydial
reinfection 273 days 271 days
Total 30,520 (100%) 14,060 (100%)
* Notifiable STIs included gonorrhea, syphilis, hepatitis B, hepatitis
C, lymphogranulomatosis and human T-lymphotropic virus (HTLV)
infections, but excluded HIV infections, since these are not usually
reported nominally in Quebec. Notifiable enteric infections included
salmonellosis, shigellosis, giardiasis, yersiniosis,
cryptosporidiosis, cyclosporosis, campylobacteriosis, amebiasis and
Escherichia coli infections. Notifiable vaccine-preventable infections
included mumps, measles, rubella, whooping cough and Haemophilus
influenzae type b infections.
Table 2. Univariate Survival Analyses of Time to Chlamydial
Reinfection, by Baseline Characteristics, for Persons <25 Years and
[greater than or equal to] 25 Years (n = 30,520), Two-year Follow-up,
Montreal, 1988-2007
Baseline Characteristics <25 Years
Reinfections Total Log rank
n (%) n p-value
Sex
Female 1376 (8.7%) 15,790 <0.0005
Male 173 (4.7%) 3668
Age (years)
10-14 58 (16.9%) 343 <0.0005
15-19 900 (10.4%) 8633
20-24 591 (5.6%) 10,482
25-29
30-39
[greater than or equal to] 40
Year
1988-1995 479 (5.4%) 8848 <0.0005
1996-2007 1070 (10.1%) 10,610
Geographic sector
South Central 454 (6.5%) 6968 <0.0005
North Central 373 (8.9%) 4156
East 451 (8.9%) 5079
West 271 (8.3%) 3255
History of other notifiable STIs
Yes 7 (7.3%) 107 0.8
No 1542 (6.5%) 19,351
History of notifiable enteric
infections
Yes 12 (16.4%) 73 0.008
No 1537 (7.9%) 19,385
History of notifiable vaccine-
preventable infections
Yes 8 (19.0%) 42 0.006
No 1541 (7.9%) 19,416
Overall 1549 (8.0%) 19,458
Baseline Characteristics [greater than or equal to] 25 Years
Reinfections Total Log rank
n (%) n p-value
Sex
Female 256 (3.8%) 6687 0.2
Male 147 (3.4%) 4375
Age (years)
10-14
15-19
20-24
25-29 207 (3.7%) 5577 0.6
30-39 143 (3.4%) 4146
[greater than or equal to] 40 53 (3.9%) 1339
Year
1988-1995 122 (2.4%) 4996 <0.0005
1996-2007 281 (4.6%) 6066
Geographic sector
South Central 179 (3.4%) 5242 0.2
North Central 93 (4.4%) 2119
East 79 (3.5%) 2275
West 52 (3.7%) 1426
History of other notifiable STIs
Yes 13 (7.3%) 177 0.004
No 390 (3.5%) 10,885
History of notifiable enteric
infections
Yes 5 (7.5%) 67 0.1
No 398 (3.6%) 10,995
History of notifiable vaccine-
preventable infections
Yes 0 (0%) 1 0.8
No 403 (3.6%) 11,061
Overall 403 (3.6%) 11,062
Table 3. Multivariate Cox Regression Analyses of Time to
Chlamydial Reinfection, by Baseline Characteristics,
for Persons <25 Years and [greater than or equal to] 25 Years
(n = 30,520), Two-year Follow-up, Montreal, 1988-2007
Baseline Characteristics <25 Years [greater than
Adjusted HR or equal to]
(95% CI) 25 Years
Adjusted HR
(95% CI)
Sex
Female 1.58 (1.34-1.85)
Male 1.00 (Referent)
Age (years)
10-14 2.98 (2.28-3.91)
15-19 1.81 (1.63-2.01)
20-24 1.00 (Referent)
Year
1988-1995 1.00 (Referent) 1.00 (Referent)
1996-2007 2.06 (1.85-2.30) 2.07 (1.67-2.56)
Geographic sector
<180 days
South Central 1.46 (1.22-1.76)
Other areas 1.00 (Referent)
[greater than or equal to]
180 days
South Central 0.71 (0.62-0.82)
Other areas 1.00 (Referent)
History of other notifiable STIs
Yes 1.79 (1.03-3.12)
No 1.00 (Referent)
