Original articles
Canadian Acute Respiratory Illness and Flu Scale (CARIFS): Development of a valid measure for childhood respiratory infections

https://doi.org/10.1016/S0895-4356(99)00238-3Get rights and content

Abstract

Although acute respiratory infection (ARI) is the most frequent clinical syndrome in childhood, there is no validated measure of its severity. Therefore a parental questionnaire was developed: the Canadian Acute Respiratory Illness Flu Scale (CARIFS). A process of item generation, item reduction, and scale construction resulted in a scale composed of 18 items covering three domains; symptoms (e.g., cough); function (e.g., play), and parental impact (e.g., clinginess). The validity of the scale was evaluated in a study of 220 children with ARI. Construct validity was assessed by comparing the CARIFS score with physician, nurse, and parental assessment of the child's health. Data were available from 206 children (94%). The CARIFS correlated well with measures of the construct (Spearman's correlations between 0.36 and 0.52). Responsiveness was shown, with 90% of children having a CARIFS score less than a quarter of its initial value, by the tenth day.

Introduction

Acute respiratory illness (ARI) is the most common illness of childhood and the most frequent reason for children's visits to a physician. A study of 273 toddlers attending 52 day-care centers found that they suffered a “cold-like” illness 23.4% of the time. This was 10 times the prevalence of the next most frequent illness, diarrhea [1]. Three quarters of the children consulted a physician at least once for these illnesses during the 6-month study period. In the United States, the annual economic costs of influenza epidemics are estimated to exceed $12 billion [2]. In Canada, physician billing alone account for over $200 million annually, excluding treatment costs [3]. Few of the treatments have been adequately evaluated, largely due to the absence of validated outcome measures.

A systematic review of 12 studies of the treatment of ARI in children found none which used a validated pediatric outcome measure of disease severity [4]. Each of these studies used a new method of assessing treatment success. Seven studies used parent-recorded symptom diaries, but none gave data on the diary's measurement properties. Five studies used outcomes recorded by the physician only, although these children were all treated as outpatients, and so the physician is likely to have limited perception of the illness.

Stein has classified disease severity measures based on the scope of disease effects measured [5]. Her four levels of scale are: Biological, Clinical, Functional, and the Financial or Social Burden of Illness. From the patient's perspective, it is the third level, the functional impact of disease, that is most relevant. This was therefore the type of measure developed in this study.

There are specific challenges to developing pediatric disease severity measures. Young children, who are unable to articulate their complaints, may manifest illness with functional problems alone. Limited language abilities of young children preclude self-report measures and necessitate the use of parents, clinicians, or other proxies. Issues such as development, growth, and puberty are crucial in pediatrics. The child's place in the family, and the distinct emotional peculiarities of children all need to be taken into account when assessing a child's functional ability or disability, especially in term of quality of life.

Pediatric measures have been developed to predict mortality in serious illness [6], to predict diagnosis [7], and to measure functional components of health 8, 9 or quality of life [10] in chronic diseases, but none are suitable for assessing severity of outpatient acute illness. The purpose of this study was to develop a disease severity measure appropriate for ARI, including influenza, in children.

Section snippets

Scale development

A MEDLINE literature search (1996 to June 1997) was performed for studies of adults or children with ARI. Twenty-five appropriate items were identified in unvalidated questionnaires used as outcome measures in clinical trials of adult 11, 12, 13 and childhood ARI treatment 14, 15 and from validated pediatric general health and functional status measures. 6, 8, 9, 16, 17, 18, 19, 20 These 25 items were each written on a card. The cards, along with five blank cards, were given to three general

Data analysis

All the diary and demographic data collection forms were transcribed onto a personal computer using a digital image scanner and TELEform for Windows software (Cardiff Software, San Marcos, CA, USA). The SAS software package was used for statistical analysis (version 6.12: SAS Institute Inc, Cary, NC, USA). Analyses were performed for the entire study population as well as the subgroup with influenza infection.

Results

In total 220 patients were enrolled in the study. Data were available from the 206 (94%) who mailed back completed diaries. These children were aged 1 month to 12 years (median 3.2 years); 65 were less than two years of age, 75 were 2 to 5 years, and 66 were 5 to 12 years of age. Influenza A infection was identified in 69 (33%), another virus in 35 (17%), and no virus was identified in 102 (50%). (see Table 1).

In the 14 subjects who did not return diaries, there was no significant difference in

Discussion

Viral ARI is the only infectious disease that affects every human. Evidence of infection with respiratory syncytial virus, for example, can be found in all children who survive to their second birthday [27]. Despite this, a systematic review of 12 studies of the treatment of pediatric ARI found none which used a validated outcome measure of disease severity [4].

The CARIFS was designed to fulfil this need. It consists of problems considered important by parents and pediatricians, as shown in the

Acknowledgements

We thank the children and parents who undertook this study as well as the staff of the physicians' offices and the following study nurses: Kwong-Yim Ang, Leya Aronson, Lorelei Audas, Debra Lea, Melissa Logue, Rosalind Reyes, Sheila Robertson and Heather Samson. This study was partially funded by an unrestricted grant from Hoffmann-La Roche Inc. Dr. Jacobs is supported by a grant from the Research Institute of the Hospital for Sick Children, Drs. Dick and Young are supported by a grant from the

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