Previous history of gonococcal infection as a risk factor in patients presenting with gonorrhoea

Abstract

Summary

Recidivism is common in patients infected with gonorrhoea. Identifying the factors most closely associated with recurrent gonococcal infection can help to target health promotion and disease prevention interventions. A case-control study design was used to quantify the importance of past infection as a risk marker for gonorrhoea while controlling for other demographic and behavioural factors. Data were available for 134 cases of gonorrhoea and 150 controls. A history of gonorrhoea (odds ratio [OR] 4.36 [95% CI 1.78–10.71]) was the strongest predictor of current infection. The number of partners in the last month (OR 2.19 [95% CI 1.20–4.02]) was also significantly associated with a diagnosis of gonorrhoea. Patients presenting with gonorrhoea are a specific high-risk group who require additional interventions and should be prioritized for evidence-based, enhanced and interactive counselling.

Keywords

gonorrhea (Neisseria gonorrhoeae)Europe epidemiology prevention

Introduction

Gonorrhoea remains a common infection in young people with over 19,000 cases reported from UK genitourinary (GU) medicine clinics in 2007.¹ Untreated infection is associated with local and systemic complications, including pelvic infection that can progress to infertility, chronic pelvic pain and ectopic pregnancy. Almost one-third of patients presenting with gonorrhoea have a history of previous gonococcal infection,² which suggests that recurrence rates could be reduced if those initially presenting with gonorrhoea were targeted for more effective disease prevention measures.

This case-control study was designed to assess the relative importance of previous infection as a risk marker for gonorrhoea, controlling for other demographic and behavioural factors.

Methods

A case-control study design utilized data from patients attending a sexually transmitted infection (STI) clinic between November 2006 and April 2007. Cases had a nucleic acid amplification test (NAAT)-based diagnosis of gonorrhoea at a genital site. Controls attended over the same time period and had a negative gonorrhoea test (NAAT). The electronic clinic database and paper-based case records were reviewed to collect information on patients’ previous history of gonorrhoea, sociodemographic characteristics, ethnicity, other STIs and sexual behaviour. An index of multiple deprivation score for the locality in which each patient lived was identified using patient postcode.

A requirement for at least 266 participants (80% power, 95% confidence) was based on a power calculation to detect a 15% difference between groups for a characteristic occurring at a frequency of 30%. Data were entered into an Access database prior to analysis in the SPSS statistical package (v15.0). The dependent variable was current gonorrhoea infection status and each independent variable was assessed individually. Those found to be significant predictors were combined in a multivariate analysis and variables that became non-significant were then also dropped. Sex and age were controlled for in all analyses, and other demographic factors were treated as independent predictor variables.

Results

Information was available on 134 cases and 150 controls. A total of 27.4% (32) of cases and 5.8% (7) of controls had a past diagnosis of gonorrhoea. Significant differences were seen between cases and controls for sex but not for age (Table 1).

Table 1

Factors associated with current gonorrhoea infection

	Univariate logistic regression ^*		Multivariate logistic regression^†
Variable	Odds ratio (95% CI)	P value	Odds ratio (95% CI)	P value
Age	0.99 (0.97–1.02)	0.600	0.97 (0.94–1.01)	0.058
Sex (female)	0.55 (0.34–0.89)	0.014	0.98 (0.28–1.02)	0.231
Ethnicity
White	Reference category
Black African	1.81 (0.60–5.43)	0.292
Black Caribbean	2.61 (1.48–4.61)	0.001
Asian	3.38(1.15–9.93)	0.027
Black Other	3.19 (1.28–7.91)	0.012
Other	2.51 (0.63–7.91)	0.193
MSM	1.50 (0.55–4.01)	0.432
Symptomatic presentation to GU medicine	0.98 (0.57–1.69)	0.939
Currently pregnant	1.27 (0.21–7.61)	0.795
Past history of gonorrhoea	5.69 (2.37–13.69)	<0.001	4.36 (1.78–10.71)	0.001
History of STI other than gonorrhoea	1.17 (0.72–1.91)	0.519
Inconsistent condom use	2.29 (1.04–5.05)	0.040
Number of partners in last month	2.08 (1.16–3.74)	0.014	2.19 (1.20–4.02)	0.011
Number of partners in last year	1.09 (0.98–1.18)	0.131
New partner in the last three months	1.37 (0.76–2.44)	0.289
Contact of a person with an STI	1.05 (0.49–2.22)	0.657
Deprivation (IMD score)	1.01 (1.00–1.03)	0.048

Age and sex was controlled for in all univariate analyses, except when examining age and sex variables directly

†

Initially variables significant at the <0.05 level in the univariate analysis were included, any variables subsequently found to be non-significant were then dropped from this model with the exception of age and sex

MSM = men who have sex with men; STI = sexually transmitted infection; IMD = index of multiple deprivation; GU = genitourinary

Current gonorrhoea infection was predicted in the univariate regression by past gonorrhoea infection, ethnicity, deprivation score, inconsistent use of condoms and numbers of partners in the last year (Table 1).

While past gonorrhoea infection did predict current infection, a history of other STIs (chlamydia, syphilis, HIV, genital warts and trichomonas), combined or individually, did not significantly predict current gonorrhoea infection (P = 0.11–0.69).

Only a history of gonorrhoea infection (odds ratio [OR] 4.36 [95% CI 1.78–10.71]) and number of partners in the last month (OR 2.19 [95% CI 1.20–4.02]) were significant in the multivariate model (Table 1).

Despite only 27.5% of gonorrhoea cases having a previous history of gonorrhoea, of those patients attending GU medicine with a past history of gonorrhoea, 27.4% (positive predictive value) were diagnosed with gonorrhoea at that attendance.

Discussion

In STI clinic attendees there is a substantially increased risk of gonorrhoea if a patient has previously had gonorrhoea, even after controlling for confounders and other significant predictors. This relationship was seen specifically with a past history of gonorrhoea and not with a past history of other STIs, suggesting that past history of gonorrhoea is not just indicating risky behaviour, but re-infection within defined core transmitter groups.

Previous studies, which were performed before the more sensitive NAAT technology was available, have reported an association between previous gonorrhoea and current infection of variable magnitude, with OR/relative risk between 1.16 and 5.6.^{3

5} A systematic review, looking only at men, concluded that prior STI was strongly associated with the risk of a repeat infection with chlamydia or gonorrhoea but did not report relative risks.⁶

Specific interventions have been recommended to help prevent re-infection with STIs^7,8 but are most effective when they include multiple counselling sessions that are difficult to implement in routine practice.^8,9 Identifying those at highest risk of infection allows clinics to focus their efforts and target available resources effectively. In patients presenting to an STI medicine clinic in the UK we found that previous history of gonorrhoea was the factor most strongly associated with current gonococcal infection.

Up to one-third of patients presenting with gonorrhoea in England have had the same infection previously which indicates that current counselling and prevention strategies are not fully effective. Our results suggest that patients presenting with gonorrhoea are a specific high-risk group who require additional interventions and should be prioritized for evidence-based, enhanced and interactive counselling.

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