Content Validation of Sickle Cell Pain Diaries for Caregivers: Results from Interviews with Caregivers

Background:

Sickle Cell Disease (SCD) is a genetic, progressive, vascular disease that affects approximately 100,000 children and adults in the US. Vaso-occlusive crises (VOCs), also referred to as pain crises, are a primary complication of SCD. VOCs are caused by several factors, including inflamed, damaged vasculature and increased cellular adherence to the endothelium and other cells, resulting in occlusion of the microvascular systems. VOCs have been associated with increased morbidity and mortality.

Healthcare visit data partially reflect VOC and SCD outcomes for children and provide understanding of healthcare resource utilization (HCRU), but miss the breadth and depth of the burden of SCD, and fail to capture daily variations of pain and other quality of life (QoL) concepts. This is particularly problematic for children, who may experience less frequent VOCs and may have lower HCRU, but will likely experience progressive non-VOC SCD-related symptoms and impacts as they age. Further, evaluating HCRU data underestimates the burden of SCD; patients who avoid seeking care outside the home are not represented.

The Sickle Cell Pain Diary - Caregiver Report (SCPD-C) is a daily observer-reported outcome (ObsRO) measure for use with caregivers of patients with SCD under 12. Two diary versions were developed for SCD caregivers: one for school age children (SCPD-CS) and one for non-school age children (SCPD-CN). The diaries were designed to capture the frequency and severity of pain during and outside of a VOC and to examine the impact of SCD-related pain on other QoL concepts. The objective of this study was to investigate the content validity of the SCPD-CS and SCPD-CN.

Methods:

Two rounds of 90-minute in-depth, hybrid concept elicitation and cognitive debriefing (CD) interviews and one round of 60-minute CD interviews (N=22) were conducted in person (n=8) and by phone (n=14) with caregivers of SCD patients aged ≤11. Interviewers used a semi-structured guide to explore concepts relevant to caregivers' observations of VOC in children, and to test the diaries.

The CD portion of the interviews required caregivers to state their thoughts while reading the diary aloud; interviewers elicited feedback on the diary instructions, recall period, items, and response choices. All interviews were recorded, transcribed, coded and analyzed.

Results:

Round 1 interviews (N=6), confirmed the relevance of the SCPD-C for most caregivers; however, several items were reported as not relevant for patients aged ≤3 years. Therefore the SCPD-C was split into the SCPD-CS for school age children and SCPD-CN for non-school age children. Other changes resulting from round 1 included: adding 8 items, removing 1, and wording edits for clarity and consistency.

In round 2 interviews (N=3), only the SCPD-CS was tested and 2 items were added for electronic programming purposes. Round 3 (N=13) tested both the revised SCPD-CS and the SCPD-CN. Caregivers confirmed the relevance and comprehensibility of both diaries; no new items were added. Minor wording revisions were made to improve readability. Final changes to the diaries included adding skip logic to ensure transition to an electronic format. Saturation analyses revealed that no additional interviews were needed.

Conclusions:

This study provided evidence that supports the content validity of the SCPD-CS (formerly SCPD-C) and SCPD-CN, observer-reported daily diaries focused on capturing daily variations of pain in SCD. While we intended to evaluate the content validity of a single caregiver diary (SCPD-C) for SCD patients aged ≤11 years, we found that two versions were required to accurately capture caregivers' perspectives relative to their child's age and school attendance status. Evidence gathered during caregiver interviews indicated that the SCPD-CS and SCPD-CN are valuable measures of VOC-related pain frequency and severity and the impact of this pain on other QoL concepts including fatigue and emotional health. In addition, the diaries capture the QoL of patients outside of HCRU, providing a more holistic view of the impact of VOCs and SCD. Future work includes development of scoring algorithms and user's manuals, and conducting psychometric validation. Use of the diaries in clinical trials with caregivers of patients who experience VOCs is anticipated, to capture the QoL impacts of new interventions designed to reduce the frequency and intensity of VOCs