Dementia May Be Underdiagnosed in States With Motor Vehicle Reporting Mandates

Mandating clinicians to report drivers with dementia may be associated with missed or delayed dementia diagnoses, a cross-sectional study of primary care providers suggested.

Clinicians in states that required them to report drivers had an adjusted 12.4% probability of underdiagnosing dementia, according to Soeren Mattke, MD, DSc, of the University of Southern California in Los Angeles, and co-authors.

This was higher than the probability of underdiagnosis in states that required drivers to self-report dementia (7.8%) or states with no reporting mandates (7.7%) by about 4 percentage points (P<0.001), the researchers said in JAMA Network Open.

"Our findings, while preliminary, suggest that the interference in the physician-patient relationship might have the unintended consequence of reducing dementia detection rates," Mattke told MedPage Today.

"Failure to diagnose deprives patients of opportunities for early intervention," he continued. "Since we could not identify any positive effects of those policies, it is not clear that they are beneficial."

The aging population creates a complex challenge for policymakers, clinicians, and society, Mattke and colleagues noted.

"Although numerous studies have explored the association between cognitive decline and road safety, few have focused specifically on reporting policies, and none, to our knowledge, have focused on the unintended consequences of such policies," they wrote. "Our study is the first to provide empirical evidence for the potential adverse effects of reporting policies."

Earlier research showed that physician reporting laws were not associated with a lower likelihood of dementia among hospitalized drivers after a vehicle crash. And while few states mandate that clinicians notify the Department of Motor Vehicles (DMV) about a dementia diagnosis, the American Medical Association's Code of Ethics outlines physicians' responsibility to recognize impairments in patients' driving ability that pose a threat to public safety and may need to be reported.

To evaluate differences between states with or without clinician reporting requirements, Mattke and co-authors used data from the 100% Medicare fee-for-service program and Medicare Advantage plans from 2017 to 2019, assessing dementia diagnoses for 223,036 primary care clinicians who had at least 25 Medicare patients. They also analyzed the reporting guidelines in each state's legislation and the state's DMV website.

The main outcome was whether a clinician underdiagnosed dementia. The researchers estimated each clinician's expected number of dementia cases using a predictive model based on patient characteristics.

Four states -- California, Delaware, Oregon, and Pennsylvania -- had clinician reporting mandates. Fourteen states had mandates requiring drivers to self-report dementia diagnoses; 32 states and the District of Columbia did not have explicit requirements.

In states with clinician reporting mandates, 91.9% of primary care clinicians worked in a metropolitan area and 19.9% of the patient panel was dually eligible for Medicare and Medicaid. In states with patient self-reporting mandates, 83.1% of clinicians worked in a metropolitan area and 15.4% of patients had dual Medicare and Medicaid eligibility. And in states without mandates, 83.0% of clinicians worked in a metropolitan area and 14.6% of patients qualified for both Medicare and Medicaid.

An estimated 17.0% of primary care clinicians underdiagnosed dementia in states with clinician reporting mandates -- more than twice the rate than in states with driver self-reporting mandates (7.1%) or without mandates (7.1%, P<0.001) -- Mattke and colleagues said.

Clinicians practicing in small towns or rural areas had higher odds of underdiagnosing dementia than those in metropolitan areas. Overall, geriatric specialists had the lowest odds of underdiagnosing compared with other clinicians.

Several factors may have influenced the findings in this study, noted Donald Redelmeier, MD, and Vidhi Bhatt, BSc, both of the University of Toronto in Canada, in an accompanying editorial.

"One interpretation of an observed correlation is direct causality; for example, mandatory reporting might prevent vehicle crashes, lead to fewer cases of brain injury, and ultimately avert cognitive declines in later life. A different interpretation is reverse causality; for example, some adults with early cognitive decline might leave California due to the high cost of living, prevailing traffic congestion, or other pressures," Redelmeier and Bhatt wrote.

"A third interpretation is confounding; for example, adults in California might be more likely to exercise regularly and become less prone to dementia and to driving," they added. "A final interpretation is measurement artifact; for example, an apparent decrease in dementia might reflect biased self-report."

It's not clear what drove the relationship that emerged in this study, Mattke and colleagues acknowledged, but the findings suggest the need to consider the effect of mandatory clinician reporting.

"In other states, patients could have a discussion with their physician whether and to what degree their cognitive decline means that they need to change driving behavior. This could mean driving less, or driving only in low-risk situations, or stopping entirely," Mattke said.

"Keep in mind that all states permit a physician to report patients if they sense they are a danger to themselves or others," he pointed out. "They are just not obligated to do so."

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