A diagnosis often marks the moment a disease becomes visible to clinicians, but the disease itself may have been developing for years. Jacob Simmering, PhD, uses large healthcare datasets to better understand that process and opportunities for early care.
An assistant professor of Pulmonary, Critical Care, and Occupational Medicine, Simmering studies health services and outcomes research. Much of his recent work focuses on neurodegenerative disorders, particularly Parkinson’s disease, which is often diagnosed long after its progression starts.
“People can experience symptoms for years, potentially even a decade, before they’re diagnosed,” Simmering said. “But when the neuron’s dead, the neuron’s dead. If we’re only studying people who are diagnosed, we might be trying too late.”
Simmering and his team analyze large insurance claims databases to identify patterns in patients’ healthcare use before they are diagnosed with Parkinson’s. By comparing people who later develop the disease with those who do not, they hope to identify signals that set the groups apart.
“If we’re trying to treat hypertension by identifying people with kidney failure, our outcomes are probably not very good,” he said. “But if we identify people with hypertension when they have hypertension, we probably have pretty good outcomes. The same logic applies with Parkinsons—if we catch it earlier, this creates a better chance of testing whether treatment can actually change its course.”
Simmering is also pursuing this goal through remote, at-home monitoring. In an ongoing study, he works with people who have recently been diagnosed with Parkinson’s and with patients who have an essential tremor. The latter condition can look nearly identical to Parkinson’s, but unlike Parkinson’s, it does not progress. To test whether a distinction could be made earlier, Simmering’s team records patients performing simple motor tasks on standard video cameras, then converts the footage into a 3D model of the hand to score movement. They also have patients complete speech tasks and wear activity trackers to gather more data. Some assessments are being tested over telehealth calls to see if this data can be captured remotely.
This project aims to improve access, which is an ongoing challenge in neurology. Movement disorder specialists are in short supply, and patients—particularly those in rural areas—often face long waits or travel significant distances before receiving an evaluation. Simmering hopes that these low-cost tools improve triage and direct patients to specialty care sooner, making earlier diagnosis possible.
The project pairs well with his other research using insurance claims, which also looks for signs of disease that precede an official diagnosis.
“If we’re only studying people after they’ve been diagnosed, we may already be too late to see the full benefit of an intervention,” he said. “The earlier we can identify someone who is on that path, the better chance we have to understand whether treatments can actually change the course of disease.”
His research also explores what happens in the aftermath of a formal diagnosis. Using insurance data that connects family members on the same healthcare plan, Simmering has looked at how a Parkinson’s diagnosis affects both patients and their spouses.
“We often think of Parkinson’s disease as something that happens to one person,” Simmering said. “But there are effects that happen inside these relationships—the spouse is experiencing living with Parkinson’s disease too, even without having the pathology themselves.”
His team found that spouses of people newly diagnosed with Parkinson’s are more likely to seek outpatient mental health care but may skip some of their own routine care. They also have higher rates of hospitalization and spend more on healthcare compared to spouses whose partners do not have Parkinson’s. Some of these hospitalizations can be traced back to conditions that could typically be managed through effective outpatient care. This suggests that caregiving responsibilities may affect a spouse’s ability to prioritize their own health, highlighting how disease affects entire support networks.
For Simmering, these questions sit at the intersection of epidemiology, health services research, and preventive care. Understanding how diseases influence families and long-term outcomes can help healthcare systems better support patients and caregivers alike.
The work also reflects what first drew him to population health research.
One study that left a lasting impression on how Simmering approaches research was not related to neurodegenerative disease. As a postdoctoral scholar, Simmering collaborated with University of Iowa urologists to track opioid use after kidney stone procedures. Patients received daily text messages asking about their pain levels and how many pain pills they had taken.
Patients were routinely prescribed 30 opioid pills after surgery, but most used only five. “We were able to quantify what was actually happening instead of relying on assumptions,” Simmering said. “Once we saw the data, it became obvious we could safely reduce the number of pills being prescribed without negatively affecting patients.”
These findings led to changes in prescribing practices, reducing the number of unused opioid pills while maintaining effective pain control. Simmering said the project demonstrated the power of asking practical questions and using data to answer them.
For Simmering, this kind of work is what he enjoys most about health services research.
“I like the fact that I work with people and diseases; there’s an opportunity to be working on pragmatic questions and using data that gives us immediate insight,” he said. “The exciting part is that sometimes you can identify something actionable right away. You can find an answer, share it with clinicians, and see it influence care much sooner than many other types of research.”