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Predictors of the prevalence of bacterial STI among young disadvantaged Indigenous people in north Queensland, Australia
  1. G C Miller1,3,
  2. R McDermott2,3,
  3. B McCulloch2,3,
  4. C K Fairley4,
  5. R Muller3
  1. 1Northern Zone Management Unit, Queensland Health, Queensland, Australia
  2. 2Tropical Public Health Unit Network, Queensland Health, Queensland, Australia
  3. 3School of Public Health and Tropical Medicine, James Cook University, Queensland, Australia
  4. 4Department of Public Health, University of Melbourne, Melbourne, Australia
  1. Correspondence to:
    Geoffrey Miller, Northern Zone Management Unit, Queensland Health, PO Box 1103, Cairns, Queensland, 4870, Australia;
    geoffreymiller{at}bigpond.com.au

Abstract

Objective: To identify sexually transmitted infections in rural and remote Indigenous communities in north eastern Australia and examine factors that may influence prevalence.

Methods: A cross sectional survey of 26 Aboriginal and Torres Strait Islander communities in northern Queensland was carried out. 3313 people (2862 Indigenous) aged 15 years and over resident in participating communities during the period March 1998 to December 2000. The main outcome measures were community and population prevalence of chlamydia and gonorrhoea and independently associated risk factors.

Results: A total of 238 cases of chlamydia, 66 cases of gonorrhoea, and 37 cases of co-infection were detected among Indigenous participants. Prevalence of chlamydia and/or gonorrhoea ranged from 23.0% among 15–19 year olds to 3.5% among those 40 years and older. In the adjusted analysis younger age, female sex, lower socioeconomic status, the use of alcohol and tobacco, and the structure of community health services were independently associated with a higher prevalence of bacterial STI.

Conclusion: This study highlights the need for improved STI control in north Queensland Indigenous communities through strategies to improve the reach and accessibility of primary healthcare services.

  • sexually transmitted infections
  • indigenous people
  • Australia

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A ccess to health care among Indigenous Australians living in remote communities is limited and this has contributed to a high prevalence of bacterial sexually transmitted infections (STI),1 pelvic inflammatory disease (PID), and infertility,2 and places these communities at risk of a substantial heterosexual HIV epidemic. Regular screening has reduced the prevalence in some communities and further gains will be made by understanding the determinants of infection.3 This report describes the results of the initial screening in 26 communities and the determinants of infection.

METHODS

The Well Person’s Health Check (WPHC) is described in detail elsewhere and was a cross sectional survey conducted between March 1998 and December 2000 in 26 rural and remote Indigenous communities in northern Queensland, Australia.4 Survey participants completed a comprehensive general health checkup that included a first void urine specimen which underwent polymerase chain reaction (PCR) testing (Roche Amplicor CT/NG, Branchburg NJ) for Chlamydia trachomatis (chlamydia) and Neisseria gonorrhoea (gonorrhoea).

Analysis

A number of individual (age, sex, alcohol and tobacco use) and community level characteristics thought to influence STI prevalence were analysed. Community characteristics included distance to the nearest secondary referral centre, road access, and the presence of a licensed liquor outlet, resident medical officer (MO), and a hospital. The population to Indigenous health worker (IHW) and registered nurse (RN) ratios, the availability and frequency of visiting specialist services (sexual health (SHS) and women’s health (WHS)), and the availability of free condoms were also considered.

The socioeconomic indices for areas (SEIFA) were used to compare the socioeconomic status of participating communities. SEIFA is a composite socioeconomic measure, which incorporates household incomes, years of education, employment, home and car ownership, and other factors.5

Analyses were performed using SPSS V106 and STATA.7 Community level data were linked to individual data. All analyses were adjusted to account for possible clustering at the community level. Variables that displayed a non-linear association with STI prevalence were categorised for analysis. Odds ratios and 95% confidence intervals were estimated using 2 × 2 tables and logistic regression. Interactions were investigated by fitting interaction terms into the regression model.

Variables with significant unadjusted odds ratios or thought to influence health service access were included in the model.

Analysis was based on 2817 Indigenous participants 15 years and older who provided urine samples. Bacterial STI is used to indicate a positive finding for chlamydia and/or gonorrhoea. There was little variation in models that examined each infection separately.

RESULTS

Most infections were identified among people aged 15–24 years (table 1). More than 90% (92% female and 96% male) of the infections detected in this survey were asymptomatic at the time of screening.8

Table 1

Age specific prevalence among Indigenous participants by sex; chlamydia, gonorrhoea, and co-infection (chlamydia and gonorrhoea)

In the unadjusted analysis (table 2), younger age, female sex, alcohol consumption, smoking, a lower SEIFA CD score, the absence of a hospital, and the absence of a resident medical officer were significantly associated with the presence of an STI. The absence of a resident medical officer and hospital in the community were highly correlated (p<0.001).

Table 2

Risk factors for bacterial STI (chlamydia and/or gonorrhoea) among Indigenous WPHC participants 15 years and older

In the adjusted analysis (table 2) younger age, female sex, alcohol consumption, smoking, and a lower SEIFA score were significantly associated with the presence of an STI. The variables hospital and resident population were also included in the final regression model; however, these factors were not statistically significant.

A wave analysis was used to examine prevalence of infection by week of attendance to assess possible participation bias. Data from screens that ran for 3 weeks (three communities, n=499) and 4 weeks (two communities, n=490) were used. The prevalence of bacterial STI was calculated by week of attendance. A difference in prevalence for each week was observed in 3 week screens (week 1 = 9.9%, week 2 = 5.2%, week 3 = 19.7%; p=0.001) and 4 week screens (week 1 = 5.2%, week 2 =12.1%, week 3 = 7.7%, week 4 = 12.2%; p=0.118). For both 3 and 4 week screens prevalence was significantly less in the first compared to the final week (3 week p = 0.009, 4 week p = 0.049). The prevalence in the final week of both screens was greater than the overall prevalence (3 week 11.1% overall and 19.7% in final week, p = 0.012; 4 week 8.8% overall, and 12.2% in final week, p = 0.33).

DISCUSSION

This study is one of the first to analyse both individual and community factors associated with STI prevalence among individuals living in remote communities.

Young age, socioeconomic disadvantage, and the structure of locally available health services emerge as strong predictors of bacterial STI prevalence. These factors provide opportunities to reduce prevalence by focusing programmes on those individuals at highest risk, and by considering community factors associated with a higher STI prevalence. This study demonstrates that screening programmes should focus on younger individuals and that such programmes cannot rely on the presence of symptoms, as most infections detected were asymptomatic.

The association between STI and substance use has been noted in a number of studies and in Australian Indigenous communities petrol sniffing and alcohol abuse have been demonstrated as risk factors for STI.9 We found the majority of survey participants drank alcohol and smoked tobacco, behaviours which are highly socially patterned. In this environment, where STI prevalence is also high, associations between the use of these substances and STI would be expected.

A number of community factors were associated with a higher prevalence of STI.

Most communities in this study occupied the SEIFA quintile of greatest disadvantage and within this group of poor communities there exists a gradient of risk that increases with increasing disadvantage.

Improving the socioeconomic status of these communities is a highly complex problem requiring long term strategies to which health services may only make a small contribution. Other factors such as those reflecting reduced access to health care are more amenable to short term solutions. Ease of access to a hospital and doctor appeared to be associated with lower STI prevalence and may indicate community confidence in accessing a particular type of health service. Issues related to perceived skills of local practitioners, confidentiality, family connections, and how health is prioritised often result in delayed presentations by Indigenous people with known conditions.10 Consideration of these factors in the design of STI screening programmes is likely to improve access to health care and to reduce prevalence.

Possible participation bias is a limitation of this study. We used a wave analysis and assume later attendees, as a group, were less likely to access health services routinely, and more likely to have a disease prevalence that closest reflects non-attendees. A second comparative method used was an analysis of clinic PCR results over a 1 year period (2000–1) in 17 communities that participated in WPHC (1998–2000). The proportion of tests found positive through clinic testing was approximately twice that of WPHC testing (data not shown). The above estimates suggest that the prevalence reported here is probably an underestimate of the true prevalence of chlamydia and gonorrhoea in these communities.

Continuing high rates of pelvic inflammatory disease (PID) among north Queensland indigenous women11 and the emerging HIV epidemic in nearby Papua New Guinea12 highlight the need to reduce STI prevalence in these populations where HIV is currently uncommon.

The provision of accessible, acceptable primary healthcare services will help; however, solutions to the underlying social and economic issues that facilitate the relative disadvantage of remote Indigenous communities are also required if the differential between the health of Indigenous and non-Indigenous Australians is to be addressed.

Acknowledgments

Funding was provided through the Commonwealth Department of Health and Family Services (now Department of Health and Aging), Queensland Health and in part by the National Health and Medical Research Council.

The authors wish to thank the large number of people who contributed to the Well Person’s Health Check and to particularly acknowledge the contributions made by Patricia Fagan, Fiona Cannon, Helen Withers, Sandra Bee, Roy Chevathen, Verna Singleton, Yoko Nakata, Judith Townsend-Stahr, Helen Laws, David Bradford, Queensland Health pathology services, and north Queensland sexual health services in supporting the sexual health aspects of the programme.

We also acknowledge the contribution of Kerry Arabena, Dympna Leonard, Helen Travers, Mark Counter, Apunipima CapeYork Health Council, and Torres Strait and Northern Peninsula Area Health Council, and thank Fiona Tulip for her assistance in data collation and Jane Hocking for assistance in data analysis.

CONTRIBUTORS
GCM, principal author, study coordination, study design, data collection, data analysis; RMcD, contributing author, study design; BMcC, data collation, data analysis; CKF, contributing author; RM, contributing author, data analysis. Note: all authors listed have made a signifi-cant contribution to this work

REFERENCES

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