Reimbursement decisions are usually based on evidence from randomized controlled trials (RCT) with high internal validity but lower external validity. Real-World Data (RWD) may provide complimentary evidence for relative effectiveness assessments (REA's) and cost-effectiveness assessments (CEA's) of treatments. This study explores to which extent RWD is incorporated in REA's and CEA's of drugs used to treat metastatic melanoma (MM) by five Health Technology Assessment (HTA) agencies.

Dossiers for MM drugs published between 1 January 2011 and 31 December 2016 were retrieved for HTA agencies in five countries: the United Kingdom (NICE), Scotland (SMC), France (HAS), Germany (IQWiG) and the Netherlands (ZIN). A standardized data-extraction form was used to extract data on RWD mentioned in the assessment and its impact on appraisal (for example, positive, negative, neutral or unknown) for both REA and CEA.

In total, fourty-nine dossiers were retrieved: NICE = 10, SMC = 13, IQWiG = 16, HAS = 8 and ZIN = 2. Nine dossiers (18.4 percent) included RWD in REA's for several parameters: to describe effectiveness (n = 5) and/or the safety (n = 2) of the drug, and/or the prevalence of MM (n = 4). CEA's were included in 25/49 dossiers (IQWiG and HAS did not perform CEA's). Of the twenty-five CEA's, twenty (80 percent) included RWD to extrapolate long-term effectiveness (n = 19), and/or identify costs associated with treatments (n = 7). When RWD was included in REA's (n = 9), its impact on the appraisal was negative (n = 4), neutral (n = 2), unknown (n = 1) or was not discussed in the appraisal (n = 2). When RWD was included in CEA's (n = 11), its impact on the appraisal varied between positive (n = 2), negative (n = 5) and unknown (n = 4).

Generally, RWD is more often included in CEA's than REA's (80 percent versus 18.4 percent, respectively). When included, RWD was mostly used to describe the effectiveness of the drug (REA) or to predict long-term effectiveness (CEA). The impact of RWD on the appraisal varied greatly within both REA's and CEA's.