Do sexual health campaigns work? An outcome evaluation of a media campaign to increase chlamydia testing among young people aged 15–24 in England

Genital Chlamydia trachomatis is the most commonly diagnosed bacterial sexually transmitted infection (STI) in the UK. The prevalence is highest in sexually active adults aged under 25 years [1, 2]. Infections are primarily asymptomatic but if left untreated can result in serious long term complications [3].

In 2003, the National Chlamydia Screening Programme (NCSP) was established in England to increase the early detection and treatment of asymptomatic infection in sexually active people aged under 25 years, in a range of settings [4]. Since its inception, there has been an increase in the proportion of young people being screened for chlamydia, and in 2010 it was estimated that 25% of all 15–24 year olds were tested for chlamydia [5]. However, the proportion of people screened has remained below the estimated 35% coverage which, at the time of the study, was deemed necessary to significantly reduce the prevalence of chlamydia [6, 7].

Mass media campaigns have been used for a range of health-related areas and have successfully achieved desirable changes in behaviour and the use of healthcare services amongst young people [8‐11]. In January 2010, the mass media campaign, “Chlamydia. Worth talking about”, was launched nationally with the aim of increasing the proportion of people aged 15–24 years having a chlamydia test in NCSP. The campaign sought to normalise conversations about the transmission of chlamydia, raise awareness of the risk of untreated infection and explain the process of diagnosis and treatment. The mass-media campaign with national TV, radio, on-line and poster advertising ran for a total of four weeks and resources (leaflets, posters and access to logos) were made available for local campaigns which continued throughout February and March [12]. The campaign material consisted of short faceless dialogues about chlamydia infection, diagnosis and treatment set in everyday situations and voiced by young people from a range of socio-demographic groups. The uptake of screening amongst 15–24 year olds was identified by the campaign developers as an indicator to evaluate the campaign.

To date, a qualitative evaluation of the campaign, based on pre and post campaign interviews with 1400 children and young people found an increase in the awareness of and testing for chlamydia, however, it did not assess actual changes in chlamydia screening uptake [13]. The aim of this study was to evaluate quantitatively, using an interrupted time series analysis, the immediate impact of the campaign on the coverage and test positivity within the NSCP by socio-demographic characteristics and self-reported sexual behaviour.

We undertook retrospective analysis using anonymised data routinely collected from the NCSP over a 27 month period (1st April 2008 to 30th June 2010). Each test record included information on the clinical source of the sample, test result, patient’s clinical history, area of residence, socio-demographic information (ethnicity, age and sex) and self-reported sexual behaviour.

A unique patient identifier based on post code of residence, date of birth and sex was created to de-duplicate the dataset. Socio-economic status for each patient was based on the overall indices of multiple deprivation (IMD) 2007 rank of their postcode of residence [14]. Patients were assigned to one of 10 Strategic Health Authority (SHA) areas according to the Primary Care Trust (PCT) code. Within the NCSP dataset, patients are assigned to one of 22 ethnic groups, which we redefined into four groups: “White”, “Black”, “Asian” and “Other”. Patient age was categorised as 15–19 and 20–24 years. Patients in the NCSP data were assigned to one of three sexual behaviour risk groups according to their response to two questions on sexual behaviour associated with higher risks of chlamydia infection; new sexual partner in last three months and two or more sexual partners in last 12 months. Patients were defined as “High risk” if at least one question was yes, “Low risk” if both questions were no and “Unknown risk” if both questions were unanswered or if either question is unanswered when the other was recorded as no [15].

The patients were assigned to a pre-campaign phase (1st April 2008 to 31st December 2009), campaign phase (1st January to 31st March 2010) and post campaign phase (1st April to 30th June 2010) according to the date of their tests. Patients were excluded from all analyses if tests were for clinical reasons, contacts of known cases, and from prisons or military services.

The NCSP is hosted by the Public Health England and permission for the use of the NSCP data was sought through the NCSP Programme. Ethical approval was not needed.

Our study found that the overall uptake of testing (coverage) did not appear to be affected by the national campaign, as the apparent increase in testing was not maintained after the secular and cyclical trends in testing were taken into account. However, we found a differential change in the coverage in the various socio-demographic groups both during and after the campaign. Testing in women and people of Black and Other ethnic origins fell during the campaign, while testing of men and people of Asian ethnicity increased. However, the increases in testing in these groups were not sustained after the campaign.

The overall proportion of people testing positive increased during the campaign, an observation that persisted in the immediate post campaign phase after adjusting for secular and cyclical trends in positivity. The campaign was associated with an increase in the positivity of chlamydia infections detected for all socio-demographic and risk groups, including people defined as having high risk sexual behaviour.

Since 2008, there has been a steady increase in the number of people tested for chlamydia through the NCSP associated with previous and ongoing national and local initiatives such as national targets, use of financial incentives and professional education programmes to promote screening [17‐20]. In addition, in the last quarter of each financial year (January to March), there have been marked increases in testing observed which have coincided with the requirement for local services to meet national coverage targets set by the Department of Health [20]. However, these initiatives and annual targets have had an equal and opposite effect on positivity, as more low risk individuals were recruited to the NCSP for testing [21]. Our study demonstrates that the increase in the number of people tested during the campaign phase was not greater than what would be expected for that time of year. However, the proportion of people testing positive during the campaign phase was more than expected and resulted in a smaller than anticipated reduction in positivity for January to March 2010.

A review of the positivity within the NCSP during 2007/08 found that women and people of black and mixed ethnicity were more likely to be tested by the programme and attributed this discrepancy in recruitment to the design and delivery of local services and initiatives [20]. In contrast, our results indicate that, unlike previous initiatives, this campaign was associated with an overall higher positivity and may have had some success in targeting groups such as men, people of Asian ethnicity and those at higher risk of having the infection that were previously not typically recruited to the NCSP.

Our study contributes to the limited and inconsistent evidence base of evaluations of mass media campaigns aimed at promoting chlamydia testing. Two studies measuring the impact of multi-media campaigns for chlamydia screening found that both the awareness of and information seeking behaviours of the target populations increased and in one study persisted for weeks after the campaign finished [22, 23]. However, neither of the studies ascertained the impact on subsequent testing behaviour. A further three studies have measured the effect of multi-media campaigns on chlamydia testing uptake. Evaluations of campaigns in Denmark and Australia concluded that their campaigns did not increase chlamydia testing [24, 25]. While an evaluation of another campaign in Australia found that chlamydia testing increased significantly for both men and women during the media campaign and was closely paralleled by an increase in chlamydia notifications. However, in that study the investigators did not control for cyclical or secular longer-term trends [26].

The timing and type of broadcast, the overall duration of campaigns as well as the integration with other campaigns have been identified as key to the success of public information campaigns and are likely to account for the discrepancy in the impact of the campaigns run to date [27]. The English campaign aimed to promote communication between individuals to encourage safer sexual behaviours and attitudes. Thus, a range of voices were used instead of casting people to deliver the key messages in order to appeal to a wider audience. The qualitative evaluation of the campaign demonstrated an increase in the number of young people aware of chlamydia and who claimed to have had a test as a result of the campaign. However, over two fifths of those interviewed felt that the campaign was not relevant to them, which may explain why we observed differential effects of the campaign on coverage and positivity in the various socio-demographic groups [13].

We have identified a number of limitations with this study. The NCSP dataset analysed includes data from services that are part of the NCSP programme. An estimated two thirds of chlamydia tests are conducted at NCSP services, thus there is the potential that the analysis may have underestimated the effect of the campaign [28].

Our analysis assumed that the changes in testing and positivity that occurred during and after the campaign phase were as a result of campaign only. The use of the already available NSCP dataset meant that we were unable to collect any additional data, such as the motivation for testing from those who were tested. We did not take into account any concurrent local campaigns or incentive schemes aimed at health professionals and/or young people which have previously been used to increase chlamydia screening and which may have been used during the campaign phase to target high risk individuals [29, 30].

It is likely that people would have attended for chlamydia testing on more than one occasion in the 27 months from April 2008 to July 2010 and so in addition to de-duplicating our dataset our analysis included an assessment for correlation. This lag analysis produced very similar results to those presented. However, the choice of lag period was limited by the number of months of data available for analysis and it is possible that results could have materially changed if there was correlation for time periods of more than two months and would have been missed by our assessment.

The exclusion of just under 30% of all records from the coverage analysis could potentially bias our results. We believe that this is unlikely as the results from the sensitivity analysis were not substantively different to those presented. A similar conclusion was reached with the sensitivity analysis of the positivity data (Additional file 1). Finally, we also assumed that the distribution of people by socioeconomic group was the same for all ethnic groups. This decision was taken on pragmatic grounds, although there is evidence that some ethnic groups are more likely to live in areas of greater deprivation [31].

This study adds to the limited evidence base of the effectiveness of media campaigns on chlamydia testing uptake and to date is the only study to assess the effect of the campaign by socio-demographic characteristics and self-reported sexual behaviour. The media campaign, once secular and cyclical trends were controlled for, was associated with an increased testing of high risk individuals and groups in the target population who were previously less likely to come forward for testing.

Our findings corroborate the claims of positive behaviour changes reported in the qualitative evaluation and together indicate that there may have been a disparity in the impact on different population groups. The content and delivery of information campaigns aimed at increasing chlamydia screening therefore need to be carefully developed to ensure that they are relevant to all sections of the target population.

This study also demonstrates the potential value of using routine national surveillance data to determine the effectiveness of population wide initiatives.