Home-based CT and NG screening programs have been conducted in many countries with a range of strategies for recruitment, test-kit delivery and specimen-collection. A number of programs were population-based, most used PTKs and some involved the use of internet for requesting test-kits. The overall median specimen return rate for programs included in this review was 51.4%, the median testing rate was 28.8% and the median CT positivity was 3.6%.
The key strength of this systematic review is the large number and range of home-based screening programs from a number of countries, which allowed examination of different strategies and outcomes. We used standardised definitions for the key outcomes to allow comparisons within and across program types. However, there are a few limitations. Firstly, we did not search the grey literature and thus may not have included other relevant unpublished programs. Secondly, we were unable to report the key outcomes for all programs, such as participation and testing rates, due to design of the programs or necessary data not being reported. Thirdly, any comparison of CT/NG positivity across the programs is limited by different target populations studied and known prevalence in the underlying populations.
This review included a number of outreach programs. The high specimen return rates in these programs indicate that majority of people agreed to provide specimens when approached in their homes. In these programs, specimen-collection was integrated into ongoing national [31
] and population-based surveys [33
], and hence incurred no significant additional cost and human resources. The downside of this approach is that such surveys are often conducted infrequently and are therefore more suitable for estimating the prevalence than being a method for ongoing screening.
The use of mailed specimens appears to have increased in popularity in recent years as most programs in this review used PTKs for screening. The recruitment strategies in these programs have varied considerably. Programs with PTKs mailed alongside an invitation have been implemented in a few European countries, but the specimen return rates were low. Programs which sent PTKs on invitation acceptance, on the other hand, were associated with relatively higher specimen return rates. Some PTK programs required the test-kits to be collected or offered at specific physical locations. These were associated with relatively less people being tested as well as low specimen return rates.
A few PTK programs in the review required the test-kits to be requested through the internet. PTKs requested in this way appear to be a logistically feasible strategy for establishing large population-based screening programs, as demonstrated by the initial results of a trial in the Netherlands [38
]. The three year results of this register-based yearly CT screening program published recently demonstrate no significant decrease in CT positivity in the target population after three screening rounds, with the testing rates declining in each round [60
]. However, among people who were screened in all three years, the positivity dropped from 5.9% to 2.9% [60
]. The number of individuals screened in the first round (n=41638) was greater than in any other program in the review [38
]. The internet can be useful for selective screening of high-risk people through the completion of online risk-assessment questionnaires, as done in less CT prevalent areas in the Netherlands [38
]. Other internet programs in the review did not involve direct invitations and relied on people actively seeking PTKs after programs were advertised [48
]. Relatively few people were tested by this approach but CT positivity was higher, which may be due to people self-selecting on the basis of their risk. The internet also provides an opportunity to deliver test results online in a confidential manner at the individual’s convenience [38
The use of reminders has shown to improve the specimen return rates [38
]. However, reminder implementation on a large scale, along with notification of results and contact-tracing, can be resource intensive [61
] and may require comprehensive registries. There may be other logistic challenges in establishing PTK programs, such as collection and transport of specimens. Clinical specimens must comply with international and national packaging requirements for transport [62
]. The current three-layered packaging system for infectious substances often results in large packages (at least one surface with minimum 100×100
mm dimension) [63
], which may require delivery and collection at the post-office or through a courier, and thus costly to transport [62
]. However, a recently developed sponge-based urine-collection device called UriSwab (Copan Diagnostics, Inc.) holds a small amount of urine after being held in the urine flow or dipped in a specimen cup. UriSwab is easy to transport, has shown good performance in detecting CT/NG infections and can potentially facilitate the establishment of PTK programs [64
]. Other considerations in home-based screening programs may include the issues of privacy and confidentiality, such as ensuring communication of results, treatment and contact tracing in a confidential manner and in-line with the individual’s preference [61
Home-based testing can potentially reduce individual screening costs by avoiding clinic fees as well as the indirect costs, such as time off work and transportation [65
]. However, there is no conclusive evidence of the cost-effectiveness of home-based screening over routine clinic-based screening. Four programs in this review provided cost information in association with home-based screening [42
]. Only Low and colleagues reported full operational cost of a PTK screening program [46
], while Domeika et al. compared the cost of home-based screening in their study with routine screening and reported the former to be about five times higher [42
]. One RCT compared the cost of home and clinic-based screening and found that home-screening provided a cost-saving ($25 per test in home vs. $111 in clinic after including direct and indirect costs) [65
], but that the cost-saving was not seen when the results were restricted to asymptomatic tests. It is thus important for future programs to focus on estimating operational costs in relation to the screening outcomes to establish the cost-effectiveness of home-based screening.