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A Day in the Life of a Clinical Research Principal Investigator (and What a Sub-I Does)

Interested in getting into clinical research as a side gig or as an additional revenue stream for your private practice but curious what running a clinical trial actually looks like day-to-day? Below, we cover what working as a principal investigator in clinical research entails, both for those running a research site by themselves and when working with the support of a site management organization (SMO). We also highlight the differences between a principal investigator (PI) and sub-investigator (sub-I).


We often work with companies that can help you establish a clinical trials site at your practice and aid with many of the logistics involved. If you would like to be alerted of clinical research opportunities matching your interests, sign up for our free clinical research matching database (you must be a member of our free physician only Physician Side Gigs group to access, but it’s completely free to join). Also sign up for our PSG weekly newsletter, where we publish current and upcoming opportunities for clinical research.


Disclosure/Disclaimer: Our content is for generalized educational purposes.  While we try to ensure it is accurate and updated, we cannot guarantee it. We are not formal financial, legal, or tax professionals and do not provide individualized advice specific to your situation. You should consult these as appropriate and/or do your own due diligence before making decisions based on this page. To learn more, visit our disclaimers and disclosures.


The day in the life of a clinical research principal investigator, from reviewing & planning to assessments, documentation & administration


Morning as a clinical research principal investigator (PI): Coffee and catch-up


A PI’s day often starts before patients arrive, reviewing overnight communications from sponsors or the study coordinator. You may need to address things such as:

  • Did any enrolled patients report side effects?

  • Are there any protocol questions?

  • Are there any issues flagged from yesterday's visits?


Unlike your regular practice, where you might jump straight into seeing patients, research demands this kind of proactive management. You're not just treating patients, you're collecting data that could change treatment standards for thousands of future patients.


If you’re working with the support of a SMO, your morning review is often more streamlined. The SMO's monitoring team should have already assessed overnight issues. You should get a summary of what needs your medical attention versus the administrative items they're handling. Instead of 30 minutes of email management, you're more likely to spend ~10 minutes on medical decisions.



Research patients arrive for appointments


These aren't your typical 15-minute appointments. Depending on the protocol, you might spend 30 minutes to 1 hour with each patient. You'll follow the study protocol exactly, including all specified questions, physical exam components, and documentation.


Your study coordinator should have already handled prep work before the appointment, including:

  • Confirming the patient's eligibility for this visit

  • Preparing case report forms

  • Gathering any required materials


Your job as the PI is the medical assessment, which includes:

  • Examining the patient

  • Evaluating their response to the investigational treatment

  • Watching for adverse events

  • Documenting everything according to protocol


Working with a SMO may be beneficial to help improve efficiency throughout this stage of the process. With a SMO, the coordinator greeting your research patient has likely been through this exact protocol at multiple sites and knows common pitfalls. This can help catch issues before they become protocol deviations, as you won’t have to train someone while trying to run a trial. You'll be working with a professional who can make your job easier.


Related PSG resource:

  • If you’re interested in establishing a clinical research site with the help of a SMO, sign up for our free clinical research matching database (physician only) to find opportunities matching your interests and expertise.



A day in the life of a PI: the documentation reality


Here's something that surprises new PIs: the paperwork is intense. You're not just writing for yourself or for insurance. You're also creating a permanent record that regulators might review. As part of this process:

  • Every observation needs documentation

  • Every conversation needs notes

  • Every deviation from protocol needs explanation


The coordinator typically handles much of this, but you as the principal investigator need to review and sign off on everything. As the PI, you're ultimately responsible for the integrity of the data coming from your site.


Working with a SMO can help optimize this process as well, as they have quality assurance specialists to review documentation before it reaches you. They can catch errors, inconsistencies, or missing data points. By the time you're reviewing and signing, you're looking at clean, complete documentation. This can save you time and reduce the anxiety of wondering if you missed something critical.



The administrative side of being a principal investigator nobody warns you about


Around lunchtime, you might have a call with the sponsor's medical monitor. They may wish to discuss enrollment progress, review a recent protocol amendment, or address a data query. These calls are part of the job, though if you work with a SMO, they can act as your liaison to the sponsor and can help manage the administrative back and forth.


You'll also be managing your research team. Your coordinator might need guidance on a challenging patient situation, or your research nurse might have questions about a new procedure. 


Being a PI means being a leader and a resource for your team.



When things don’t go as planned as a principal investigator in clinical research


Not every day running a clinical trials site is smooth. For example, you may:

  • Have a patient experience an unexpected side effect that needs immediate reporting

  • Discover a protocol deviation that needs correction

  • Have the sponsor request additional documentation from a visit that happened weeks ago


This is where having systems matters. Good documentation practices mean you can address issues without derailing your entire day. A solid team means problems get escalated appropriately. If you’re new to clinical research and working as a PI, a SMO can help walk you through established processes.


Related PSG resources:



A day in the life of a sub-investigator (sub-I): different but crucial


If you're a sub-investigator rather than the PI, your day looks different. You're not carrying the full regulatory burden, managing the study budget, dealing with contract negotiations, etc. You're not the main point of contact for sponsors.


As a Sub-I, you’ll be focused on:

  • Seeing research patients under the PI's supervision

  • Conducting study procedures

  • Documenting findings

  • Contributing to the medical oversight of the trial


What working as a sub-investigator in clinical research focuses on, from seeing patients to documentation

Think of it as being the senior resident to the PI's attending – you're doing substantive work, but someone else carries ultimate responsibility.


For many physicians who are looking to do this as a side gig, sub-I roles may be preferable. You get clinical research experience without the full administrative weight, and will be contributing meaningfully to important work. And honestly, you often have more work-life balance because you're not the one getting emergency calls about regulatory submissions (though you won’t capitalize on the full financial potential as a result).


Related PSG resources:



An afternoon as a principal investigator: regular practice meets research life


By the afternoon, you're often switching between research patients and regular patients. This is where workflow integration really matters. Your front desk needs to know which patients are study participants. Your regular nursing staff needs to understand what they might need to coordinate with your research coordinator.


It's a juggling act, but most PIs find a rhythm. The key is not trying to hide the research side of your practice – embrace it. Train your entire team and make it part of your practice. A SMO can help train your staff on research workflows with clear protocols so your staff isn’t confused about who does what.


Regardless of whether you work with a SMO or handle the administrative side of your research site internally, everyone on your team should clearly know their role for the clinical research side of your practice.



The end of your day as a PI: reviewing and planning


Before you leave, you should review the day's research activities. Your coordinator should give you a quick update on:

  • Enrollment numbers

  • Upcoming monitoring visits

  • Any issues that need your attention


You’ll sign off on completed case report forms and review the schedule for the next day's study visits.


If you’re working with a SMO, their team will help manage many of these tasks throughout the day. They should provide you with:

  • A summary dashboard of trial metrics

  • A heads-up on tomorrow's schedule

  • Any flagged items needing your attention


It's more structured than your regular practice, but many physicians find this structure to be satisfying. And they take satisfaction in this aspect of their practice because as a PI you are:

  • Contributing to something bigger

  • Giving your patients access to cutting-edge treatments

  • Staying updated with emerging therapies in your field




Conclusion: the (realistic) bottom line of working as a PI or sub-I


Being a PI or sub-I isn't just about extra income – though that's nice. It's about integrating meaningful research into your clinical practice. Some days are hectic. Some days are incredibly rewarding. Most days are both.


If the administrative burden seems overwhelming, consider working with a SMO or research network to help handle more of the logistics so you can focus on the patients, the research, and the rest of the day-to-day of your practice.



Clinical research resources for physicians


Related PSG resources:



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