Although adults have increased their use of drugs for attention-deficit/hyperactivity disorder (ADHD) in the past few years, rates of both initiation and persistence of treatment continue to be low, according to results of a recent study in the Journal of Clinical Psychopharmacology. Rates were even lower in men, racial and ethnic minorities, and younger individuals.
“Our preliminary studies and another previous report in adults suggest that a substantial proportion of adult patients with ADHD do not receive treatment,” the authors wrote. “Among those initiated on medication, treatment discontinuation is common.”
To quantify this, researchers at the University of Florida (UF), in Gainesville, FL, reviewed Medicaid fee-for-service data on nearly 24,000 adult patients in 29 states who were newly identified with ADHD between 1999 and 2010. They found that subjects’ propensity to start pharmacotherapy tripled and their rate of persisting with therapy nearly doubled during the study period. Yet the overall rates were still low—22.5% for treatment initiation and 34.2% for treatment persistence at one year.
Racial and ethnic minorities demonstrated notably lower rates of initiating medication. Black/African Americans (odds ratio [OR] 0.61), Hispanics/Latinos (OR 0.71), and other minorities (OR 0.67) were less likely than whites to initiate treatment.
“Our observation that minorities are less likely to seek and receive needed care for mental disorders is not specific to ADHD, but has been reported for a variety of other psychiatric conditions,” explained first author Yan Li, BPharm, MS, researcher in the Department of Pharmaceutical Outcomes and Policy at UF’s College of Pharmacy. “We believe better understanding and appropriate integration of sociocultural norms in treatment plans and better allocation of health care resources seem to be the most pivotal interventions to address these disparities.”
The researchers also investigated whether comorbid conditions had an effect on medication treatment. They found that schizophrenia (OR 0.70) and conduct disorders (OR 0.62) decreased the probability of initiation, but depression (OR 1.21), anxiety (OR 1.24), and substance use disorders (OR 1.13) increased the probability.
Antipsychotic use (OR 0.59) and anticonvulsant use (OR 0.83) significantly decreased the likelihood for initiating treatment, while chronic opioid use increased it (OR 1.24). Patients receiving psychotherapy at the beginning of the study were also less likely to use medication (OR 0.66).
Other notable findings:
- Men were less likely (OR 0.76) than women to get drug treatment for ADHD. “We think that’s because females tend to have greater subjective experience of impairment from disorder symptoms, which result in a greater likelihood of seeking treatment compared to males,” Li said.
- Older patients were about 50% more likely than younger patients (18- to 25-year age group) to initiate pharmacotherapy.
- Patients with preexisting cardiovascular disease and diabetes were less likely to initiate medication treatment.
- Long-acting medications were associated with better persistence, possibly because of dosing convenience, the researchers noted.
- ADHD patients started on atomoxetine were least likely to be persistent on treatment. “A possible explanation may lie in a lower response rate of atomoxetine compared with stimulants,” although other factors may be involved, the authors noted.
- Treatment initiation rates ranged widely in different states, from 7.9% in New Jersey to 47.7% in Tennessee. Besides New Jersey, Mississippi, Massachusetts, and Minnesota had initiation rates lower than 15%. Initiation rates were higher than 30% not only in Tennessee, but also in Wisconsin, Idaho, and Louisiana.
“One more interesting finding: We didn’t find any difference in treatment use between patients living in urban and rural areas,” Li said.
The increased use of ADHD drugs in recent years is encouraging, he added, but there’s still a long way to go. “Future efforts of improving the care for these patients should focus on addressing the sociodemographic disparities in using treatment and refining evidence on safe and effective treatment approaches for patients with comorbid conditions,” Li said.
This study was funded by the Florida Agency for Health Care Administration.