Diagnosis and treatment of adult attention-deficit/hyperactivity disorder at US ambulatory care visits from 1996 to 2003.

OBJECTIVE: To determine national-estimates and characteristics of United States (US) ambulatory care visits made by adults, aged 18 years or older, with attention-deficit hyperactivity disorder (ADHD) diagnosis, treatment patterns, and significant factors associated with adult-ADHD treatment.

METHODS: Retrospective analyses were conducted of the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey over a combined 8-year period (1996-2003). Mental-health disorder (including ADHD) visits were identified using International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) diagnostic codes. Significant factors of adult-ADHD treatment were determined in multivariable logistic regression analyses.

RESULTS: An estimated total 10.5 million ambulatory-ADHD visits accounted for 3.5% of 301 million adult mental-health disorder visits. The census-adjusted visit rate was 0.3-0.4%. Increasing in numbers from the year 2000, ADHD visits were most often to psychiatrists, by Caucasian men, aged 18 to 40 years. Significantly fewer ADHD visits without, versus with, psychiatric comorbidity (mainly depression) received various treatments-- behavioral (46% vs. 83%), antidepressant (18% vs. 66%), or combined behavioral and ADHD-specific (stimulant or atomoxetine) pharmacotherapy (36% vs. 57%) respectively. However, more ADHD visits without than with psychiatric comorbidity received ADHD-specific pharmacotherapy alone (76% vs. 68%) or no treatment (14% vs. 6.5%). At ADHD visits, adjusting for gender, age, and US census geographic-region, psychiatric comorbidity (odds ratio [OR], 6.5, 95% confidence interval [Cl], 3.5-12.4, p < 0.05) and self-pay reimbursement-source (OR, 2.7, 95% Cl, 1.3-5.7, p < 0.05) significantly increased the likelihood of behavioral treatment. Insurance reimbursement-sources other than private and self-pay significantly decreased the likelihood of an ADHD-specific pharmacotherapy (OR, 0.4, 95% Cl, 0.2-0.7, p < 0.05) or any ADHD-treatment (OR, 0.2, 95% Cl, 0.1-0.5, p < 0.05).

CONCLUSIONS: Adult-ADHD visits have increased in recent years, with a census-adjusted visit rate of 0.3-0.4%. Psychiatric comorbidity and reimbursement-source were associated with ADHD-treatment. Limited treatment may be a significant problem in US-ambulatory care. It is important to continue validation studies, educate providers, examine the efficacy of multimodal-treatments, and study insurance-related barriers to adult ADHD-treatment.