Patterns of correlates, comorbidity and impairment associated with attention-deficit hyperactivity disorder (ADHD) in children and youth were examined in representative samples from the community and from treatment facilities serving medically indigent youth in Puerto Rico. Information from caretakers and youths was obtained using the Diagnostic Interview Schedule for Children, (version IV), measures of global impairment, and a battery of potential correlates. In the community (N=1,896) and the treated samples (N=763), 7.5 and 26.2% of the children, respectively, met criteria for DSM-IVADHD in the previous year. Although the prevalence rates and degree of impairment differed, the general patterns of correlates, comorbidity and impairment were similar in both populations. The exceptions were associated with conduct disorder, anxiety, impairment in the ADHD comorbid group, and age factors that appeared to be related to selection into treatment.
Keywords
ADHD; Correlates; Prevalence; Comorbidity; Hispanic/LatinoThe clinical research literature has consistently shown that Attention-Deficit/Hyperactivity Disorder (ADHD) (American Psychiatric Association 1994) is a disabling disorder that affects individuals across the lifespan (Barkley et al. 1990;. However, it is not clear whether the patterns of correlates, comorbidity, and impairment of the disorder in treated samples are the same for persons identified with ADHD in probability community samples. Studying the differences in patterns is important because findings from treatment samples can be biased due to selection effects that Cohen and Cohen (1984) called, "the clinician's illusion." They argued that bias can arise because clinical studies tend to focus on persons with more chronic and severe manifestations of the disorder. Insofar as these selection effects are ignored when looking at patterns of correlates, comorbidity, and impairment, the estimates of the associations related to these patterns can be affected by statistical bias known as Berkson's bias (Angold et al. 1999;Berkson 1950). To estimate the extent of the bias, it is necessary to compare findings in treated samples and epidemiological samples, using similar study designs and measures.Treatment-referred samples are appropriate for studies that aim to generalize findings to children who receive services in clinics, and also for studies that provide initial descriptions of rare disorders when the concern is identification of potential risk factors, or when very little developmental epidemiological research has been done (Angold et al. 1999). However, when evaluating results from treated cases, researchers must keep in mind the likelihood that these cases have more symptomatology, are more impaired, and usually constitute a higher burden to caregivers than children not receiving services. Also, minority/ethnic groups and prepubertal girls may be underrepresented in clinical samples (Goodman et al. 1997). Epidemiological studies that obtain representative community samples are designed to provid...