P17. Drug retention time; a real life Swedish nationwide cohort study on InfCareHIV 2009-2014

Amanda Häggblom1, Stefan Lindbäck2, Magnus Gisslen3, Leo Flamholc4, Bo Hejdeman5, Andreas Palmborg2, Amy Leval2, Eva Herweijer6, Sverrir Valgardsson7, Veronika Svedhem8
Affiliates: 1County Council of Gävleborg Department of Infectious Diseases Gävle Sweden 2Janssen Stockholm Sweden 3Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg Department of Infectious Diseases Gothenburg Sweden 4Malmö University Hospital Department of Infectious Diseases Malmö Sweden 5Venhälsan-Södersjukhuset Department of Infectious Diseases Stockholm Sweden 6Karolinska Institutet Medical Epidemiology and Biostatistics Stockholm Sweden 7Janssen Oslo Norway 8Karolinska University Hospital Department of Infectious Diseases Stockholm Sweden

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Background
As HIV infection requires lifelong treatment, studying drug retention times and factors influencing treatment durability is essential. The Swedish database InfCareHIV includes high quality data from more than 99% of all patients diagnosed with HIV infection in Sweden and provides a unique opportunity to examine outcomes in a nationwide real world cohort.

Methods
Adult patients who started a new therapy defined as a new 3rd agent (all ARVs that are not NRTIs) 2009-2014 with more than 100 observations in treatment naive or treatment experienced patients were included. Dolutegravir was excluded due to short follow up period. Multivariate Cox proportional hazards models were used to estimate hazard ratios for treatment discontinuation.

Results
2541 treatment naive patients started 2583 episodes of treatments with a 3rd agent. Efavirenz was most commonly used (n=1096) followed by darunavir (n=504), atazanavir (n=386), lopinavir (n=292), rilpivirine (n=156) and raltegravir (n=149). In comparison with efavirenz, patients on rilpivirine were least likely to discontinue treatment (adjusted HR 0.33; 95% CI 0.20-0.54, p<0.001), while patients on lopinavir were most likely to discontinue treatment (adjusted HR 2.80; 95% CI 2.30-3.40, p<0.001). 2991 treatment experienced patients started 4552 episodes of treatments with a 3rd agent. Darunavir was most commonly used (n=1285), followed by atazanavir (n=806), efavirenz (n=694), raltegravir (n=622), rilpivirine (n=592), lopinavir (n=291) and etravirine (n=262). Compared to darunavir all other drugs except for rilpivirine had higher risk for discontinuation in the multivariate adjusted analyses; rilpivirine (HR 0.66; 95% CI 0.52-0.83, p<0.001), atazanavir (HR 1.71; 95% CI 1.48-1.97, p<0.001), efavirenz (HR 1.86; 95% CI 1.59-2.17, p<0.001), raltegravir (HR 1.35; 95% CI 1.15-1.58, p<0.001), lopinavir (HR 3.58; 95% CI 3.02-4.25, p<0.001) and etravirine (HR 1.61; 95% CI 1.31-1.98, p<0.001). Besides the ARV treatment, certain baseline characteristics of patients were independently associated with differences in drug retention time. In naive patients the use of other backbone than TDF/FTC or ABC/3TC increased the risk for early treatment discontinuation. In treatment experienced patients, detectable plasma viral load at the time of switch or being highly treatment experienced increased the risk for early treatment discontinuation.

Conclusions
Treatment durability is dependent on several factors, among others patient characteristics and ART guidelines. The choice of 3rd agent has a strong impact, with significant differences found between drugs.