Cross-sectional survey on prevalence of attention deficit hyperactivity disorder symptoms at a tertiary care health facility in Nairobi

BACKGROUND: Attention deficit hyperactivity disorder is the most common childhood neurobehavioral disorder with well documented adverse consequences in adolescence and adulthood, yet 60-80% of cases go undiagnosed. Routine screening is not practiced in most pediatric outpatient services and little information exists on factors associated with the condition in developing countries. METHODS: This was a questionnaire based cross-sectional survey whose primary objective was to determine prevalence of attention deficit hyperactivity disorder (ADHD) symptoms in children aged 6-12 years attending a tertiary care hospital Accidents and Emergency unit. Secondary objectives were to: (i) ascertain if physical injury and poor academic performance were associated with ADHD, (ii) compare diagnostic utility of parent-filled Vanderbilt Assessment Scale (VAS) against Statistical Manual of Mental Disorders-IV (DSM-IV) as the gold reference and (iii) establish if there exists an association between ADHD symptoms cluster and co-morbid conditions. RESULTS: Prevalence of cluster of symptoms consistent with ADHD was 6.3% (95% CI; 3.72-10.33) in 240 children studied. Those affected were more likely to repeat classes than the asymptomatic (OR 20.2; 95% CI 4.02-100.43). Additionally, 67% of the symptomatic had previously experienced burns and 37% post-traumatic open wounds. The odds of having an injury in the symptomatic was 2.9 (95% CI; 1.01-8.42) compared to the asymptomatic. Using DSM-IV as reference, VAS had a sensitivity of 66.7% (95%; CI 39.03-87.12) and specificity of 99.0% (95% CI; 96.1-99.2). Positive predictive value was 83.0% (95% CI; 50.4-97.3) and negative predictive value 98.0% (CI 95.1-99.1). Oppositional defiant disorder symptoms, anxiety, depression and conduct problems were not significantly associated with ADHD cluster of symptoms. CONCLUSION: The study found a relatively high prevalence of symptoms associated with ADHD. Symptomatic children experienced poor school performance. These findings support introduction of a policy on routine screening for ADHD in pediatric outpatient service. Positive history of injury and poor academic performance should trigger further evaluation for ADHD. Vanderbilt assessment scale is easier to administer than DSM-IV but has low sensitivity and high specificity that make it inappropriate for screening. It however provides a suitable alternative confirmatory test to determine who among clinically symptomatic patients requires referral to a psychiatrist.