It is appropriate for the principal investigator to oversee all of the data and safety monitoring when the study population is small, the study is overseen by a single investigator, and the range of study events that could have an important impact on the risks and benefits of research is narrow. Investigators are typically responsible for data and safety monitoring in Phase I and Phase II clinical trials. The rationale for this is that in studies with small subject populations, toxicity may be more readily apparent through close monitoring of individual patients. In social-behavioral research the data and safety monitoring is almost always conducted by the principal investigator.
Data and safety monitoring may be conducted by employees of the study sponsor when monitoring is too complex for a single investigator. Although there is no clear guidance from the regulatory agencies on the circumstances under which sponsor-controlled monitoring systems are appropriate, they are routinely used in industry-sponsored multicenter clinical trials for studies in which death or severe disability is not a major risk to subjects. When death or severe disability is a major risk to subjects, an independent DSMC is most often established.
A DSMC is responsible for monitoring data generated in the most complex studies and those representing higher risks to subjects. Although an exact specification of when a DSMC should be established has not been worked out, the following factors are often used:
Highly influential factors that often lead to a decision to use a DSMC:
- The study design is double-blind (double-blind studies tend to use DSMCs)
- The study phase (most Phase III studies use DSMCs - and most are double-blind)
- The size of the study population (studies using large subject populations tend to use DSMCs)
Other factors that may influence the decision to use a DSMC:
- The risk level imposed on subjects (studies using highly toxic therapies or dangerous procedures may use DSMCs)
- The number of study sites (studies conducted at multiple sites may use DSMCs)
- The rates of expected morbidity or mortality in the study population (when high rates of morbidity or mortality are expected, a DSMC may be used)
- The vulnerability of the study population (studies involving vulnerable populations are more likely to use DSMCs)
DSMCs are further described at the following link.
No matter who is responsible for data and safety monitoring it is essential that a strong, effective line of communication be established between the investigator and his/her IRB, who together exercise their responsibility to protect human subjects locally.