Human growth hormone (hGH) is produced and excreted by the anterior pituitary gland to help fuel growth during childhood and to maintain tissues and organs throughout life. In recent decades, recombinant hGH has been used to treat short stature or growth failure in children, including the following: 1) growth hormone deficiency, 2) born small for gestational age, 3) Prader-Willi syndrome, 4) Turner syndrome, 5) chronic renal insufficiency, and 6) idiopathic short stature. Most children receive injections daily and treatment usually is carried out over several years, until the child achieves an acceptable adult height or maximum growth.
In order to achieve optimal therapeutic results, adherence to long-term, continuous hGH administration is essential. Ease of use is recognized by parents, physicians and nurses as a key feature in device acceptance with potential to improve adherence. Injection devices, such as pre-filled syringes and manual injector pens, have been developed to make the process of preparing and administering hGH easier and more convenient. There are several different injection devices available on the market, including the Genotropin® pen (i.e., reusable pen). Several steps must be completed in order to prepare the pen and to inject the hGH, including inserting a cartridge, mixing the medicine, inserting a needle, getting rid of air bubbles, using the needle guard, choosing or dialing the dose and finally injecting hGH. Depending on the age of the child, either the parent, the child, or both participate in preparing the injection pen and administering the medication. As such, patient-reported outcomes (PRO) measures developed to assess these injection devices should include feedback from both parents and children to better reflect how these devices are used in practice.
Another reason for obtaining parent–child opinions together is based on findings from the literature suggesting variability in perceptions of disease impact between parent and child in health-related quality of life (HRQL)[4–8]. It has been suggested that good parent–child agreement is seen for items that are concrete and observable (e.g., physical aspects of health), and poor agreement for items that require judgment (e.g., emotional or social aspects of health). However, a recent review of the literature suggests that levels of parent–child agreement may be influenced by the relevance of a domain to a disease and to the consequent parental involvement to care for the child, not merely by the objectivity of the domain. That is, parent–child agreement may be higher when the parent is more involved in caring for the child in a domain that is more influenced by disease. For example, in patients with rheumatoid arthritis, in which physical function is impacted, parents may need to provide more assistance with physical activities and may be more aware of their child’s physical functioning, resulting in stronger agreement on domains that measure the physical impact of disease. In this population, concordance in HRQL scores between parents and children was 0.71 for physical functioning, which was stronger than concordance for emotional functioning and worry (r = 0.51 and 0.48, respectively).
For measures that evaluate domains or activities with high parent–child involvement, such as injection pen preparation and use, a dyadic approach may be useful to overcome concordance issues that arise in obtaining information separately from the parent-child. Although little research has been conducted to evaluate the parent-child dyad relationship in developing PRO questionnaires or in responding to PRO questionnaires, a qualitative analysis of parent–child dyad approach by Ungar and colleagues suggests that a dyadic approach could be helpful to children in enabling them to answer questionnaire items as accurately as possible. When responding to HRQL questionnaires together, parents were a valuable resource to their children (ages 8–15 years) and helped them overcome problems with recall or comprehension that they may have had with the questionnaire. It was noted that child participants would look to their parents to corroborate answers, help remember events and clarify the meaning of questions, words or phrases. Additional studies are needed to better understand this methodological approach, including evaluations of the psychometric properties of measures that are administered to parent and children together.
The Injection Pen Assessment Questionnaire (IPAQ) was developed to evaluate patient (i.e., children 8 to 18 years old) and parent perceptions of ease of use and preference for attributes of injection pens used to administer hGH. The questionnaire was designed to be administered to parent–child dyads, where dyads together are asked to complete a single copy of the questionnaires. The objectives of this study were to examine the psychometric properties of the IPAQ including the following: 1) item and scale characteristics (e.g., frequencies, item distributions, and factor structure), 2) reliability, and 3) validity.