Original Article
Asthma severity scores for preschoolers displayed weaknesses in reliability, validity, and responsiveness

https://doi.org/10.1016/j.jclinepi.2004.02.016Get rights and content

Abstract

Objective

To evaluate the measurement properties of asthma severity scores for use in preschool children.

Methods

A Medline search was used to identify published asthma severity scores for use in preschool children. The measurement properties of the scores (item development, reliability, validity, responsiveness, and usability) were evaluated using a published framework.

Results

Ten asthma severity scores were identified, with 19 different clinical variables used as items. Interrater agreement was assessed by five scores. Only two scores—Clinical Asthma Score (CAS) and Respiratory Distress Assessment Index (RDAI)—reported good agreement based on weighted κ-statistics (0.64–0.90). Construct validity was reported by the CAS, Clinical Asthma Evaluation Score (CAES), the Clinical Symptom Grading System (CSGS), and the Preschool Respiratory Assessment Measure (PRAM). Correlation coefficients between asthma severity scores and clinical measures (length of stay, drug dosing interval, O2 saturation, health professional assessment, PaO2, PaCO2) ranged from 0.47 to 0.70. Responsiveness was formally demonstrated for two scales (PRAM, CAS).

Conclusions

Most asthma severity scales for use in preschool children have been informally developed. Recently developed scores (CAS, PRAM) have more rigorously evaluated their measurement properties. Research is needed to directly compare the asthma severity scores developed for use in preschool children.

Introduction

Acute asthma is a common pediatric medical emergency. For example, each year in the United States, asthma is responsible for two million emergency department (ED) visits by children and youth, with 15–25% of these children requiring hospital admission [1]. Across the pediatric age range, preschool children account for the majority of asthma ED visits and hospital admissions [2], [3].

The measurement of acute asthma severity in young children is important both for clinical decision making and evaluation of treatment effectiveness. In general, pulmonary function testing provides information on the severity of airway obstruction; however, commonly used measures of pulmonary function, such as forced expiratory volume at 1 second (FEV1) and peak expiratory flow, are unreliable in young children [4]. In addition, pulmonary function testing is often not feasible in acutely ill children, and may not be available in the ED setting. Last, normative values for these physiological measures in young children are not available [4].

Given that pulmonary function testing in preschool children is often neither feasible nor reliable, many clinical scores of asthma severity have been developed. A 1994 paper by Van der Windt et al. [5] assessed the clinical and research applicability of 16 asthma severity scores for use in children 0–18 years of age. The objective of this review was to evaluate the measurement properties of clinical asthma severity scores for use in preschool children (0–6 years).

Section snippets

Materials and methods

A Medline search (1966–2002, inclusive) was conducted to identify all studies describing the development or use of a clinical asthma severity score for children 6 years of age or younger.

Results

The literature search identified ten clinical asthma severity scores for use in preschool children. These are, in alphabetic order: Bronchiolitis Score (BS) [13], Clinical Asthma Score (CAS) [14], Clinical Asthma Evaluation Score (CAES) [15], Clinical Score (CS) [16], Clinical Symptom Grading System (CSGS) [17], Clinical Scoring System-1 (CSS1) [18], Clinical Scoring System-2 (CSS2) [19], Pulmonary Index (PI) [20], Preschool Respiratory Assessment Measure (PRAM) [21], and the Respiratory

Discussion

Evaluation of the measurement properties of clinical asthma severity scores for use in preschool children showed that most scores have been developed in an ad hoc manner. Of the asthma severity scores identified, only 4 of the 10 scores assessed individual items, 5 assessed reliability (with only 2 reporting correlation coefficients), and only 4 formally assessed validity (with only 3 reporting correlation coefficients). Eight scores assessed responsiveness in the context of asthma treatment.

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