US Pediatricians Often Overlook Steps in Diagnosing SMA, Surveys Show

Many U.S. pediatricians fail to use developmental screening tools and are not familiar with the diagnostic requirements for spinal muscular atrophy (SMA), a study drawing on results of two surveys conducted by Cure SMA reported.

These findings, from responses given by hundreds of pediatricians, support a continuing need to expand SMA awareness, and a need for a more timely referral to specialists and shorter wait times, the researchers said.

The study, “Awareness screening and referral patterns among pediatricians in the United States related to early clinical features of spinal muscular atrophy (SMA),” was published in the journal BMC Pediatrics.

SMA is an inherited neuromuscular disorder characterized by progressive muscle weakness and shrinkage (atrophy)caused by the loss of motor neurons, which are specialized nerve cells that control voluntary muscle movement. Although early diagnosis and treatment are critical to allow for effective therapy before permanent neuron damage occurs, significant delays in diagnosis persist. 

Studies indicate infants with SMA type 1, the most severe and common form of the disease, are not identified until a mean age of about six months, despite the average age of symptom onset occurring at two and a half months.

SMA was added to the federal Recommended Uniform Screening Panel (RUSP) for newborn screening in 2018, shortly after the approval of its first disease-modifying therapy, Spinraza, in late 2016. However, at the time this study, published in May, only 34 states had adopted these recommendations, with 68% of infants receiving SMA screening.

“Despite significant progress, the lack of universal adoption of newborn screening represents a missed opportunity for early diagnosis,” the researchers wrote.

To better understand the underlying reasons for these diagnostic delays and to identify obstacles to be addressed, Cure SMA surveyed pediatricians in 2018 and again 2019.

The goal of the first survey was to examine their familiarity with SMA, while the second follow-up survey assessed pediatricians’ adherence to the American Academy of Pediatrics (AAP) developmental screening program, as well as surveillance guidelines and referral patterns.

Together, these surveys supported Cure SMA’s ongoing SMArt Moves initiative, an awareness and educational campaign launched in 2018 to help healthcare professionals and parents recognize and diagnose SMA at an early stage.

This study reported on the outcomes of these two surveys as described by researchers at Cure SMA.

Specifically, the 2018 survey included 11 questions focused on awareness of SMA, diagnostic requirements, and use of developmental screening tool. The 2019 survey had 27 questions seeking practice information and data about patterns and barriers to specialist referrals. Additional questions allowed for comparison over the year that separated the two surveys.

The first survey was completed by 300 pediatricians, and the second survey received 600 responses. In total, 42 specialists completed the two surveys.

Results of the first survey found 52.7% of the pediatricians correctly indicated that genetic screening is needed to make a definitive SMA diagnosis, while 31% chose muscle biopsy, which “indicated a lack of awareness about the diagnostic requirements for SMA,” the researchers wrote.

Results from the second survey were similar, and revealed a decrease in the percent of providers correctly identifying genetic testing to diagnose SMA — 52.7% in 2018 vs. 45.0% in 2019.

“In the 2019 survey, responses indicate a persistent lack of awareness of the diagnostic requirements for SMA,” the researchers wrote.

When asked how screening tools were used in the clinic in 2018, 56.0% of respondents indicated testing at each visit. Also, 41.3% used screening tools at the nine-, 18-, and 30-month visits, 32.7% screened infants as soon as concerns appeared, and 18.0% said they tested at both timepoints.

In the 2019 survey the question was revised for clarity. Here, 37.3% of responding pediatricians said they used screening tools at each visit, and 35.7% indicated their use at the 9-, 18-, and 30-month visits and as concerns appeared in checking developmental milestones. However, 15.0% of pediatricians only used genetic testing at the nine-, 18-, and 30-month visits and not screening tools as concerns appeared, indicating “a persistent underutilization of developmental screening tools,” the team wrote.

Notably, providers that recently completed their medical training (0 to 10 years of experience) were 1.549 times more likely to use genetic screening tools at every visit, or at nine-, 18-, and 30-month visits than those with more than 10 years of experience.

Most respondents to the 2018 survey, 74.7%, used as a clinic screening tool the Ages and Stages Questionnaire (ASQ-3), while 29.3% used the Denver-II Developmental Screening Test and the Parents’ Evaluation of Developmental Status (PEDS). In 2019, 67.5% indicated using the ASQ-3 as a screening tool, 35.2% the Denver-II Developmental Screening Test, and 32.7% used the PEDS.

Furthermore, in the 2018 survey, 55.3% of pediatricians said they would immediately refer a child to early treatment if they observed decreased muscle tone (hypotonia), while 52.0% would immediately refer the child to a pediatric neurologist for evaluation.  About half, 50.3%, said they would schedule a return visit within a month, 14.0% would ‘wait and see’ or evaluate at the next regular visit, and 17.7% would order a creatinine kinase test, a marker for muscle damage.

A total of 70.3% of respondents indicated they were comfortable identifying the early signs of a neuromuscular disorder, and 67.3% said they were familiar with SMA; however, only 59.4% of this group correctly noted the genetic testing requirement.

In the 2019 survey, 55.0% of pediatricians said they had referred less than 5% of patients to a neurologist over the previous year, with 35.5% reporting referrals for 5 to 10% of patients, 6.0% for 11 to 15% of patients, and 2.5% noted referrals for 16 to 20% of patients. Those that referred more than 20% represented 1% of all respondents.

About two-thirds (390 out of 600) of these pediatricians referred patients to a neurologist once or twice for hypotonia in the prior year. Among the others, 24.5% reported making quarterly referrals, while 10.5% noted monthly referrals.

Pediatricians identified appointment wait time (defined as the number of days between a referral order and a specialist appointment date) as the primary factor when selecting a neurologist, followed by a specialist’s previous experience, insurance coverage, quality of communication, and reputation.

Wait times for the first appointment with a neurologist was one to six months, reported by 64.2% of respondents in 2019, with most waiting between one to two months. Barriers to shorter wait times included restrictions due to insurance coverage, lack of triage (ability to assess urgency) at specialists’ offices, and lack of neurologists within the region.

Overall, “many pediatricians underutilize developmental screening tools and lack familiarity with diagnostic requirements for SMA,” the team concluded. “Continuing efforts to expand awareness and remove barriers to timely referral to SMA specialists, including reducing appointment wait times, are needed.”