
Medical affairs and commercial teams have organized around key opinion leaders for decades, and for good reason: the experts who run pivotal trials and write treatment guidelines shape clinical practice for years. But a growing share of scientific influence now plays out somewhere else entirely — on X, LinkedIn, YouTube, podcasts, and open online communities — and it is often driven by voices who never appear on a traditional KOL list. Analyses of major oncology congresses show that discussion of new data on social platforms has grown steadily for over a decade, with interpretation of headline results forming online during the meeting itself, not after publication [1, 2]. Teams that only watch traditional channels see that shift late.
This article lays out what separates a KOL from a DOL, where the two overlap, and what that means for how life sciences teams build their engagement strategy.
What is a KOL (Key Opinion Leader)?
A key opinion leader (KOL) is a physician, researcher, or other healthcare expert whose credentials and body of work give them outsized influence over how their peers think and practice. That influence is built through the traditional machinery of scientific authority: peer-reviewed publications, clinical trial leadership, guideline committee membership, podium presentations at major congresses, and senior roles at academic medical centers and professional societies.
KOL influence tends to be deep and institutional. A single KOL may shape guidelines that direct treatment decisions for years, lead the registrational trials behind a new therapy, or train a generation of specialists in their field. It is slow-building influence — and durable.
What is a DOL (Digital Opinion Leader)?
A digital opinion leader (DOL) is a healthcare voice whose influence operates primarily through digital and social channels: X, LinkedIn, YouTube, podcasts, blogs, and online medical communities. The term was popularized by the Medical Affairs Professional Society, which began describing DOLs around 2018 as healthcare professionals who influence public health and its implementation through digital activity [3]; researchers have since characterized DOLs as clinicians with substantial online followings who play a central role in disseminating health information and countering misinformation [4].
DOL influence tends to be fast and broad. When results drop at a major congress, DOLs are often the first to summarize, contextualize, and critique them — reaching audiences in the tens of thousands before the formal literature responds. A 2024 analysis of 354 breast cancer oncologists found their social activity spiked around ESMO, ASCO, and San Antonio Breast, with DOL posts drawing tens of thousands of views apiece during those windows [5]. Many DOLs are practicing clinicians; others are researchers, pharmacists, patient advocates, or medical educators.
KOL vs. DOL: the key differences
KOL
DOL
Primary channels
Publications, congresses, guidelines, advisory boards
Social media, podcasts, video, online communities
Nature of influence
Deep, institutional, slow-building
Fast, broad, conversational
Typical audience
Peer specialists, institutions
Clinicians, trainees, patients, public
How influence is measured
Publication and citation record, trial leadership, guideline roles
Reach, engagement, share of voice, network position
Speed of impact
Months to years
Hours to days

Frequently Asked Questions
Is a DOL the same as an influencer?
Can someone be both a KOL and a DOL?
How is DOL influence measured?
Why do medical affairs teams track DOLs?
References
Pemmaraju N, Thompson MA, Mesa RA, Desai T. Analysis of the Use and Impact of Twitter During American Society of Clinical Oncology Annual Meetings From 2011 to 2016: Focus on Advanced Metrics and User Trends. J Oncol Pract. 2017;13(7):e623–e631. https://pubmed.ncbi.nlm.nih.gov/28514195/
European Society for Medical Oncology (ESMO) 2018 Congress Twitter analysis: from ethics to results through the understanding of communication and interaction flows. ESMO Open. 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7046424/ (verify author list before publishing)
Komodo Health. Identifying Key Opinion Leaders in an Online World. https://www.komodohealth.com/perspectives/identifying-key-opinion-leaders-in-an-online-world/ (secondary source for the MAPS 2018 definition — confirm against MAPS primary material)
Green A, Wu S, Di Pasquale A, Pang T. The Role of Digital Opinion Leaders in Dengue Prevention Through Health Promotion and Public Health Collaboration: Qualitative Semistructured Interview Study. J Med Internet Res. 2025;27:e70997. https://www.jmir.org/2025/1/e70997
Creation Healthcare. Analysis of 13,789 posts by 354 breast cancer oncologists, Jan–Dec 2024. Reported in Oncology News Today, March 2025. https://oncologynewstoday.co.uk/breast-cancer-oncologists-use-social-media-to-engage-with-latest-research-network-with-peers-and-educate-wider-public-study-finds/
Medical Affairs Professional Society. Digital Opinion Leaders and HCP Influence Mapping — 2025 MAPS Roundtable. https://medicalaffairs.org/dol-hcp-influence/
Medical Affairs Specialist. Harnessing Digital Opinion Leaders and HCP Influence Mapping to Transform Medical Affairs Strategies. 2025. https://medicalaffairsspecialist.org/blog/harnessing-digital-opinion-leaders-and-hcp-influence-mapping-to-transform-medical-affairs-strategies
