Point‐of‐care hepatitis C testing and treatment strategy for people attending harm reduction and addiction centres for hepatitis C elimination

Abstract According to WHO goals, the elimination of Hepatitis C Virus (HCV) by 2030 requires enhancing and simplifying HCV testing. Our aim was to create a model to assess and compare different strategies for HCV testing, linkage to care and treatment among people who access harm reduction centres (HRC) and Addiction Centres in Catalonia. A decision tree model was designed to evaluate two strategies: Hepatitis C Point‐of‐care (POC) “test and treat”, at the community versus standard‐of‐care (SOC), in which HCV testing was performed at community and therapy at the hospital. Both strategies were assessed separately in HRCs (6,878 users) and Addiction Centres (13,778 users). with a time horizon of 18 months. Healthcare outcomes were HCV testing, linkage to care, treatment outcomes and reinfection rate. HCV testing was performed in 3,178 (46%) of the HRC users. Compared with SOC, POC increased access to treatment by 57% (63% vs. 6%). SVR rates were 64% in POC vs. 23% in SOC. Reinfection rates were 21% with POC compared to 24% with SOC. With POC, losses to follow‐up were reduced by 41%. In the Addiction Centres, 12,566 users (91%) were screened using the two strategies. Compared to the SOC, POC increased access to treatment and linkage to care by 19% along with SVR at the same rate. Reinfection rates decreased by 6%. Thus, the implementation of a POC “test and treat” strategy at HRCs and Addiction Centres has shown to be an effective public health strategy to help eliminating HCV in accordance with WHO goal.

The target population was defined as the total number of new users annually attending the HRCs (6,878 users) and the ACs (13,778 users) based on the drug information system of Catalonia. 3 The same percentages of users screened and the number of HCV RNApositive patients were assumed for both strategies, according to the type of centre. A literature search was performed to obtain data to develop the decision tree (percentages of users screened, HCV RNA positivity, referral to hospital, treatment initiation, SVR rates in an intention to treat (ITT) analysis, no response and reinfection). The expert panel provided an estimation for data in which the information was not available. [4][5][6][7][8][9] (Table S1 and Figure S1).
For each type of centre, the results of the POC and SOC strategies were compared in terms of linkage to care, access to treatment, the SVR at the 12-week follow-up after the end of antiviral therapy (SVR12) and the reinfection rate.

| Harm reduction centres
In the simulation, among 6,878 users attending HRCs in both strategies, 3,178 (46%) accepted testing, and 1,764 (56%) were HCV RNA positive. POC strategy compared to the SOC strategy increased access to treatment by 57% (63% vs. 6%) over the total number of viraemic patients and increased the SVR rates by 41% (64% vs. 23%). The remaining 31% (339 users) in the POC group and 72% (75 users) in the SOC group were considered as lost to follow-up. The incidence of reinfection was 4% lower in the POC group (Figure 1).
Of the total viraemic patients, the POC strategy avoided 42% of the viraemic patients from being lost to follow-up or being untreated over the study period.

| Addiction centres
Among users attending ACs (13,778 users), 12,566 were screened for HCV RNA, and 2,251 active infections were detected with both strategies. Compared with the SOC strategy, POC showed a 19% increase in access to treatment and in the response rate. Of the remaining patients, 155 (13%) vs. 235 (30%) were lost to follow-up; thus, the POC strategy decreased the number of patients lost to follow-up by 17%. In the POC strategy, none of the patients developed reinfection, while in the SOC strategy group, reinfection occurred in 6% (Figure 1). Therefore, the POC strategy decreased the proportion of patients lost to follow-up or not treated/not linked to the health system by 23% throughout the analysis period.

| DISCUSS ION
Antibody tests for HCV have been available in a number of drug addiction care centres for years in Catalonia. 10 However, this strategy has not been demonstrated to guarantee linkage to specialized care and treatment; thus, it is necessary to promote effective strategies in this area. For this reason, our analysis compared two diagnostic and treatment strategies for viraemic HCV users attending HRCs and ACs.
The main difference between the two strategies consisted of the need for referral to hospitals or not. To compare the strategies, a model using a decision tree was constructed that allowed the simulation of the different interventions and the extrapolation of the results. It should be noted that the data included in the analysis were obtained from a large group of representative centres involved in public health in the area. For the modelling, the data were extrapolated to the entire population attending HRCs and ACs in Catalonia.
Using data from the same community gives consistency to the analysis and reinforces its results.
The results of the analysis showed clear differences between the two strategies. The traditional referral route, in which the initiation of treatment requires additional follow-up visits, causes users to disengage from medical care and to finally not access treatment. 2 Our results showed that compared to the SOC strategy, making tests and treatment available in the same centres that drug users usually attend (the POC strategy) decreases losses to follow-up and increases the number of users who start antiviral treatment and achieve SVR. In addition, the POC strategy slightly decreased the number of reinfections, and although in the HRCs, the reinfection rate remained above 20%. This fact could be explained because, regardless of the strategy implemented, the target population is people who present risk practices for HCV transmission. In evaluating these results, we must consider that they are based on a theoretical model that performs a simplified simulation of the two examined strategies. Nevertheless, this model was validated by a panel of experts, and therefore, its results should be considered valid estimates that can aid in decisionmaking in clinical practice and in public health policies.
On the other hand, the contribution of the POC strategy in the treatment of hepatitis C can also be evaluated based on our results.
The use of a 'test and treat' approach in POCs helps ensure the immediate transition from diagnosis to treatment and, therefore, helps avoid viraemic users being lost to follow-up. Consequently, a greater