Validating an Asthma Case Detection Instrument in a Head Start Sample

Article excerpt

The need for school-based instruments to detect children who have asthma symptoms but no diagnosis and children with diagnosed asthma that is poorly controlled has been carefully examined by Wheeler, Boss, and colleagues. (1,2) Asthma and myopia are the 2 most common chronic conditions in childhood. (3) Screening within preschool populations is routine for myopia but not for asthma even though asthma is a leading cause of hospitalization, emergency department visits, and school absence among children in economically disadvantaged communities such as East and Central Harlem in New York City. (4,5) In disadvantaged communities of color, child care is provided through Head Start and other subsidized preschool programs, so it is not surprising that Head Start populations are characterized by high asthma prevalence and associated morbidity. (6-8) Head Start is a federally subsidized preschool program that serves approximately 900,000 children nationwide primarily from low-income families, (9) with mandates to identify health concerns and link families to continuous care. (10) Based on numerous studies showing that asthma can be controlled once appropriately treated (11) and on the growing understanding that permanent airway obstruction may result when asthma is uncontrolled over a sustained period, (12) clinical specialists increasingly emphasize the importance of diagnosing asthma early in life. There are no validated published case detection instruments for use in Head Start and subsidized preschool settings. The preschool programs in which the present study was conducted relied on parents or physicians to identify children with asthma. However, ample evidence that asthma is often not recognized and diagnosed among young children (13-15) argues for developing and validating tools to detect preschool children who may need medical referrals for evaluation and treatment of asthma.

Development of a case detection instrument for Head Start and subsidized preschool populations can be informed by validation studies conducted in elementary school populations. (16,17) As there is no "gold standard" definition of asthma, (2) common yardsticks to measure the ability of the instrument to detect children with probable asthma have included clinical evaluation consisting of medical history and physical examination, (18-20) medical record review, (21) and comparison with a more detailed interview of the parent. (22) To address concerns that false positives might unnecessarily burden already strained medical practices in economically disadvantaged communities, additional validation measures have included historical diagnosis of asthma plus methacholine challenge, (18) spirometry, (20,23) and spirometry plus exercise challenge. (24,25) As part of a study to evaluate an asthma education intervention in Head Start and subsidized preschool settings, a case detection instrument was created to target the families for the intervention. This paper reports on the psychometric qualities of the case detection instrument.

METHODS

Participants

This study was conducted in fall 1999 and winter 2000. Participants were recruited at Head Start and subsidized preschool programs in East and Central Harlem whose enrollment totaled 645 students. The program in East Harlem, which provides subsidized preschool services to approximately one sixth of eligible families in the community, serves a community that is 55% Latino and 33% African American, where 38% of the households are headed by a single parent, 46% of residents over 25 years have not graduated high school, and 38% of the residents live in poverty. (26) The program in Central Harlem is the largest preschool provider in that community, whose ethnic composition is 67% African American and 20% Hispanic, with 36% single-parent households, 34% of residents over 25 years not graduating high school, and 35% of residents living in poverty. (27)

Instruments

Brief Respiratory Questionnaire--Administered by Preschool Personnel. …