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The PedsQL™ Infant Scales: feasibility, internal consistency reliability, and validity in healthy and ill infants

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Abstract

Objective

The PedsQL™ (Pediatric Quality of Life Inventory™) is a modular instrument designed to measure health-related quality of life (HRQOL) and disease-specific symptoms in children and adolescents ages 2–18. The new PedsQL™ Infant Scales were designed as a generic HRQOL instrument specifically for healthy and ill infants ages 1–24 months. The objective of this study was to report on the initial feasibility, internal consistency reliability, and validity of the PedsQL™ Infant Scales in healthy, acutely ill, and chronically ill infants.

Methods

The 36-item (ages 1–12 months) and 45-item (ages 13–24 months) PedsQL™ Infant Scales (Physical Functioning, Physical Symptoms, Emotional Functioning, Social Functioning, Cognitive Functioning) were completed by 683 parents of healthy, acutely ill, and chronically ill infants.

Results

The PedsQL™ Infant Scales evidenced minimal missing responses, achieved excellent internal consistency reliability for the Total Scale Scores (α = 0.92), distinguished between healthy infants and acutely and chronically ill infants, and demonstrated a confirmatory factor structure largely consistent with the a priori conceptual model.

Conclusions

The results demonstrate the initial measurement properties of the PedsQL™ Infant Scales in healthy and ill infants. The findings suggest that the PedsQL™ Infant Scales may be utilized in the evaluation of generic HRQOL in infants ages 1–24 months.

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Abbreviations

PedsQL™:

Pediatric Quality of Life Inventory™

FDA:

Food and Drug Administration

HRQOL:

Health-related quality of life

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Acknowledgments

This research was funded in part by intramural grants from the Texas A&M University Research Foundation and the Scott and White Memorial Hospital Research Foundation.

Competing Interests

Dr. Varni holds the copyright and the trademark for the PedsQL™ and receives financial compensation from the Mapi Research Trust, which is a non-profit research institute that charges distribution fees to for-profit companies that use the Pediatric Quality of Life Inventory™.

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Correspondence to James W. Varni.

Additional information

The PedsQL™ is available at http://www.pedsql.org.

Appendix: Steps in the development of the PedsQL™ Infant Scales

Appendix: Steps in the development of the PedsQL™ Infant Scales

A review of the empirical literature on infant health-related quality of life (HRQOL) was conducted. From the review of the literature, discussions with healthcare providers who work with infants, and our experience with the PedsQL™ 4.0 Generic Core Scales and the PedsQL™ Disease-Specific Modules for ages 2–18, a conceptual model was developed of the domains of interest (i.e., physical functioning, physical symptoms, emotional functioning, social functioning, cognitive functioning, and daycare functioning). From this conceptual model, a semi-structured open-ended interview script was developed.

Feedback was obtained from healthcare professionals on the items and scales generated from the focus interviews of 61 parents with infants ages 1–24 months. Pre-testing and cognitive interviews (conducted in 2007) were used to obtain feedback on the items and scales generated from the focus interviews of 61 parents from an additional 24 parents of healthy infants and infants with acute and chronic health conditions, ages 1–24 months. Specifically, parents were asked to first complete the questionnaire and then review each item and provide feedback on clarity of wording and relevance of content. A rating scale was utilized to ascertain the perceived importance of each item for infant HRQOL from the parents’ perspective. One of the main goals of the cognitive interviews was to detect question items, terms, or response options that were difficult to understand or that were misunderstood by the respondents. Items were revised based on the feedback provided in the pre-test and cognitive interviews, and the preliminary PedsQL™ Infant Scales were constructed that consisted of 66 items on the 1–12 months Version and 99 items on the 13–24 months Version. Each age format consisted of the same 6 scales (i.e., Physical Functioning, Physical Symptoms, Emotional Functioning, Social Functioning, Cognitive Functioning, and Daycare Functioning) and the same 66 items on the 1–12 months Version were on the 13–24 months Version with the addition of 33 age-appropriate items. Instructions and response scales for the Infant Scales were created to be consistent with the instructions and response scales of the PedsQL™ 4.0 Generic Core Scales for ages 2–18 years and the other PedsQL™ Disease-Specific Modules. That is, the instructions asked how much of a problem each item had been during the past 1 month for the child. A 5-point response scale was utilized (0 = never a problem; 1 = almost never a problem; 2 = sometimes a problem; 3 = often a problem; 4 = almost always a problem).

From 2007 to 2009, field testing of the PedsQL™ Infant Scales was conducted at 4 data collections centers across the United States. The sample included 683 parents of infants ages 1–24 months recruited from general pediatric clinics, subspecialty clinics, and hospitals. Based on data from the field test, the number of missing responses per item was first evaluated. Items with greater than 50% missing responses were eliminated. During this step, the Daycare Functioning Scale was deleted from both the 1–12 months and 13–24 months Versions given that items across this scale had more than 50% missing values. Next, a principal components analysis of the PedsQL™ Infant Scales individual items was performed utilizing the SPSS Factor procedure to further reduce the number of items. Items were retained that loaded at least 0.30 onto their corresponding factor. Next, the internal consistency of the items on each subscale was evaluated. Items that were found to decrease the internal consistency of the scale below the minimum Cronbach alpha of 0.70 were eliminated. Finally, the clinical meaningfulness of items was also considered, in that items were retained for inclusion (even if they were not selected via statistical means) if they were determined to provide important and relevant information about an infant’s health.

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Varni, J.W., Limbers, C.A., Neighbors, K. et al. The PedsQL™ Infant Scales: feasibility, internal consistency reliability, and validity in healthy and ill infants. Qual Life Res 20, 45–55 (2011). https://doi.org/10.1007/s11136-010-9730-5

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