Background: Patient (pt) involvement in treatment decisions or 'shared decision making' has been associated with increased pt satisfaction, increased compliance to advice from health professionals, enhanced treatment adherence and overall improved treatment outcomes. Methods: A multinational non-interventional cross-sectional survey was designed and aimed to enrol approximately 1,000 adult pts with multiple myeloma (MM) through Myeloma Patients Europe's (MPE) member network across 12 participating countries: France, Israel, Netherlands, United Kingdom (UK), Sweden, Germany, Hungary, Austria, Finland, Switzerland, Poland and Romania. Patient advocacy organizations were asked to disseminate a URL link for the survey to pts by posting the link on their website, e-mailing the link to pt members on their mailing list or through social media. The primary survey objective was to describe pt confidence in making an informed treatment decision. Main secondary objectives were to describe how pt confidence in making an informed treatment decision was associated with types of information, importance of information and sources of information. Pts fulfilling the following criteria were included: adults who had started MM treatment and received at least one dose, who were able to self-report diagnosis of MM and recall the decision-making process at the start of their most recent line of treatment, and who were able and willing to complete an online questionnaire lasting approximately 30 minutes. Results: Out of 4325 pts who accessed the online survey link, 1559 pts fulfilled eligibility criteria and were included in the primary analysis, of which 1081 provided fully completed surveys. France, Israel, Netherlands, and UK were the largest recruiters with over 200 pts each. Median age of respondents was 54-64 years. Time since diagnosis was 0-4 years for over half of pts (53.1%), and ≥16 years since diagnosis for 4.8% of pts. The majority of pts had received 1 line (40.1%, n=592) of anti-MM treatment, 20.5% (n=303) of pts had received 2 lines, 16.0% (n=236) of pts had received 3 lines, and 19.9% (n=294) reported having received 4 or more lines of treatment. Last treatment decision was taken 2 years ago for another 25.5% of respondents. Of the 1112 pts who responded to the question for the primary objective, half of pts (54.4%, n=605) reported being very confident in their most recent treatment decision, and 37.2% (n=414) of pts reported being somewhat confident. Similarly, over half of pts (56.8%, n=634/1116) felt that they were 'very involved' in their last treatment decision, 28.4% (n=317/1116) reported being 'somewhat involved'. Confidence in making an informed treatment decision did not appear to differ by lines of therapy, primary treating physician, type of clinic primarily treated at, or whether help from a carer was received. In terms of types of information received, pts most commonly received information on location of treatment (84.5%, n=1037), mode of administration (83.0%, n=1019), frequency of treatment (77.7%, n=953) and common side effects (72.2%, n=886), and least commonly received information on overall survival (OS) benefit (38.4%, n=471) and how long until MM returns (30.9%,n=379) or healthcare provider costs (20.0%, n=245). Information relating to treatment effectiveness (OS benefit, likelihood treatment would work, how long until MM returns) were reported as the most important types of information amongst those who received them, followed by types relating to treatment tolerability (how safe the treatment is). Operational aspects of treatment (mode of administration, location of treatment and healthcare provider costs) were considered the least important type of information. Receiving the types of information perceived as most important by pts was significantly associated with increased pt confidence in making an informed treatment decision. Conclusion: The most important types of information to pts with MM are related to treatment effectiveness and tolerability. However, effectiveness seems to be communicated to pts less frequently than tolerability and this may be due to the uncertainty surrounding this type of information. However, the survey results suggest some elements on effectiveness should be considered to be shared with pts to increase their confidence in making an informed treatment decision. Disclosures Brescianini: Amgen: Current Employment, Current equity holder in publicly-traded company. Desgraz:Amgen: Current equity holder in publicly-traded company, Ended employment in the past 24 months. Plate:Pfizer: Research Funding, Speakers Bureau; Roche: Research Funding, Speakers Bureau; Sanofi: Research Funding, Speakers Bureau; Takeda: Research Funding, Speakers Bureau; ASCO: Membership on an entity's Board of Directors or advisory committees; ESMO: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding, Speakers Bureau; Amgen: Research Funding, Speakers Bureau; Myeloma Patients Europe: Current Employment; Novartis: Research Funding, Speakers Bureau; Mundipharma: Research Funding, Speakers Bureau; Karyopharm: Research Funding, Speakers Bureau; Janssen: Research Funding, Speakers Bureau; GSK: Research Funding, Speakers Bureau; Oncopeptides: Research Funding, Speakers Bureau. Morgan:Amgen, BMS, GSK, Janssen, Karyopharm, MundiPharma, Novartis, Oncopeptides, Pfizer, Roche, Sanofi, Takeda: Research Funding, Speakers Bureau; Myeloma Patients Europe: Current Employment. Vallejo:Amgen, BMS, GSK, Janssen, Karyopharm, MundiPharma, Novartis, Oncopeptides, Pfizer, Roche, Sanofi, Takeda: Research Funding; Myeloma Patients Europe: Current Employment. Wetten:Amgen: Current Employment, Current equity holder in publicly-traded company. DeCosta:Amgen Ltd: Current Employment, Current equity holder in publicly-traded company. Suzan:Amgen: Current Employment, Current equity holder in publicly-traded company.