Direct comparison
Clinical Trial Monitoring Types Compared
On-site, remote, centralized, and risk-based monitoring compared: what each checks, when sponsors use it, and what ICH E6(R2) recommends.
Side-by-side comparison
| Dimension | On-Site Monitoring | Remote Monitoring | Centralized Monitoring | Risk-Based Monitoring (RBM) |
|---|---|---|---|---|
| What it is | In-person visit by a sponsor/CRA to a trial site (SIV, recurring IMVs, COV) | Same site-specific checklist as on-site, performed off-site via secure remote access to records | Remote, systematic review of accumulating data aggregated across ALL sites | The overarching strategy that decides which technique(s) apply where, how often, and how deeply |
| Where the review happens | At the investigator site, in person | Off-site, but still one site’s records reviewed individually | Centrally, across the whole trial at once | Not a location — a plan that allocates the other three |
| What's checked | Informed consent docs, SDV against source, IP accountability, essential-document currency, AE/SAE reporting (ICH E6(R2) 5.18.4) | Same items as on-site, reviewed via remote access to scanned/electronic source records | Enrollment/dropout rates, deviation frequency, AE patterns, lab outliers, query timeliness — vs. KRIs/QTLs | Whatever the trial's documented monitoring plan specifies, informed by pre-identified critical data/processes |
| Regulatory basis | ICH E6(R2) Section 5.18 (monitoring purpose and activities) | Not a separately defined ICH E6(R2) visit type — an off-site way of performing Section 5.18 activities | ICH E6(R2) Section 5.18.3 (defines the term); Section 5.0.4 (QTLs) | ICH E6(R2) Section 5.0 (Quality Management) and 5.18.3, which permit an on-site-only, combined, or justified centralized-only approach |
| Grew out of / popularized by | The traditional default monitoring model predating RBM guidance | Practical necessity during COVID-19-era travel restrictions; persisted post-pandemic where feasible | FDA's August 2013 RBM guidance and TransCelerate BioPharma's June 2013 methodology paper | Same FDA 2013 guidance and TransCelerate paper, formalized into ICH E6(R2) with the 2016 addendum |
| Typical scheduling | Historically fixed-interval; under RBM, risk-adjusted (e.g. every 4–8 weeks depending on site risk) | Substitutes for or supplements on-site IMVs at a similar risk-adjusted cadence | Continuous / ongoing (e.g. weekly dashboard review), not episodic visits | Sets the cadence and depth for the other three per a documented, risk-adjusted plan |
| Main strength | Direct, first-hand view of site conditions, facilities, and informal practices no remote technique fully replaces | Keeps site-specific, document-level review going without travel time/cost | Surfaces cross-site patterns a single site visit can't see; directs limited on-site effort to where risk actually is | Allocates finite monitoring resources to where they most reduce risk, instead of spreading them evenly regardless of need |
| Main limitation | Resource- and travel-intensive; fixed-interval on-site-only visiting does not scale efficiently to risk | Depends on a site's technical ability and local privacy/regulatory rules permitting secure remote record access | Can't verify document-level accuracy or observe physical site conditions directly; only as good as the data flowing into it | Requires upfront investment in defining KRIs/QTLs and a documented, defensible risk rationale |
| Relationship to the others | The baseline technique that centralized monitoring and RBM reallocate rather than eliminate | A delivery-mechanism variant of on-site-style review — distinct from centralized monitoring’s aggregate, cross-site scope | One specific technique within RBM — a component of it, not synonymous with it | The umbrella strategy; on-site, remote, and centralized monitoring are the tools it blends per a documented plan |
Common questions
FAQ
Does ICH E6(R2) require risk-based monitoring?+
ICH E6(R2) doesn't mandate one single technique for every trial, but it explicitly recommends developing a systematic, prioritized, risk-based approach to monitoring, and it permits a sponsor to justify and document a centralized-monitoring-only approach where trial-specific risk supports it (Section 5.18.3).
Can centralized monitoring completely replace on-site visits?+
ICH E6(R2) allows a centralized-only approach where justified and documented, but most trials still keep at least some on-site presence — the Site Initiation Visit and Close-Out Visit in particular — because checks like investigational product storage conditions and physical document custody can't be verified remotely.
What's the actual difference between remote monitoring and centralized monitoring?+
Remote monitoring is site-specific — the same document-level checklist as an on-site visit, just performed off-site. Centralized monitoring is cross-site and aggregate — pattern analysis across the whole trial’s accumulating data. They are often used together but are not the same technique.
Who decides which monitoring approach a trial uses?+
The sponsor, or a CRO acting on the sponsor's behalf under ICH E6(R2) Section 5.2, decides and documents the approach in the trial's monitoring plan, informed by a risk assessment covering the investigational product, trial design, and site-specific risk factors.
