Physicians experienced no major changes in patient volume or complexity since the Affordable Care Act’s coverage expansion provisions took effect, a study shows.

Of patient encounters, 22.9% of primary care visits in 2014 were by new patients, compared with 22.6% of visits to primary care physicians in 2013, according to a study by athenahealth and funded by the Robert Wood Johnson Foundation. Similar small increases were reported for pediatricians and surgeons, while the proportion of new-patient visits remained flat for obstetricians and gynecologists.

The findings contradict widely held predictions that the ACA would drive a flood of sicker, newly insured patients into doctors’ offices, said Josh Gray, vice president of athenaResearch for athenahealth.

“Amongst other findings and counter to what many predicted, we haven’t seen a swell of new and sicker patients materialize in primary care or across specialty settings,” Mr. Gray said in a statement. “Also, there’s no evidence that providers are overwhelmed by an uptick of patients with more complex cases or chronic diseases. The findings are fascinating; it’s a front-row seat into how policy is translated into care trends, utilization, and access across the United States.”

Researchers at athenahealth reviewed data from roughly 15,700 physicians who used athenahealth’s cloud-based software from 2013 to 2014. Of the doctors, 35% were primary care physicians, 7% were pediatricians, 7% were ob.gyns, and about 12% were surgeons. The data reflect 29 million patient encounters. (The sample does not include visits to emergency departments or inpatient settings.)

For pediatricians, 22.9% of visits in 2014 were new, compared with 22.3% of visits in 2013. New visits for ob.gyns remained at 31.5% of total patient encounters in 2014, the same proportion seen in 2013. For surgeons, 50% of their patient visits were new in 2014, compared with 49.5% in 2013. For all other physicians, new-patient visits fell from 37.1% in 2013 to 36.1% in 2014.

Patients did not appear to be sicker or more complex in 2014, the study showed. Physicians’ average work relative value unit (RVU) score per patient visit remained unchanged from 2013 to 2014, at 2.3. RVUs take into account the time, skill, and intensity of treatment per patient visit. Diagnoses per visit rose slightly, from 2 in 2013 to 2.1 in 2014, while the number of high-complexity evaluation and management codes declined from 8% in 2013 to 7.5% in 2014 for all visits.

While size and complexity of patient visits remained mostly stable, the number of uninsured patients fell, particularly in states that have expanded Medicaid, the researchers found.

Among patients in Medicaid expansion states, the proportion of visits by uninsured patients to primary care physicians dropped from 4.6% in 2013 to 2.8% in 2014. For patients in states that have not expanded Medicaid, the proportion of uninsured patient visits fell from 7% in 2013 to 6.2% percent in 2014.

Although providers did not see a major rise in new patients, doctors are more likely to conduct comprehensive new-patient assessments. The proportion of visits for comprehensive evaluation and management of new patients – including taking a patient history, conducting a physical exam, and making medical decisions – increased from 6.7% in 2013 to 7% in 2014.

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