The Content Validity of a Chemotherapy-Induced Peripheral Neuropathy Patient-Reported Outcome Measure

Abstract

Purpose/Objectives To test the content validity of a 16-item version of the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire–Chemotherapy-Induced Peripheral Neuropathy (QLQ-CIPN20). Research Approach Cross-sectional, prospective, qualitative design. Setting Six outpatient oncology clinics within the University of Michigan Health System’s comprehensive cancer center in Ann Arbor. Participants 25 adults with multiple myeloma or breast, gynecologic, gastrointestinal, or head and neck malignancies experiencing peripheral neuropathy caused by neurotoxic chemotherapy. Methodologic Approach Cognitive interviewing methodology was used to evaluate the content validity of a 16-item version of the QLQ-CIPN20 instrument. Findings Minor changes were made to three questions to enhance readability. Twelve questions were revised to define unfamiliar terminology, clarify the location of neuropathy, and emphasize important aspects. One question was deleted because of clinical and conceptual redundancy with other items, as well as concerns regarding generalizability and social desirability. Interpretation Cognitive interviewing methodology revealed inconsistencies between patients’ understanding and researchers’ intent, along with points that required clarification to avoid misunderstanding. Implications for Nursing Patients’ interpretations of the instrument’s items were inconsistent with the intended meanings of the questions. One item was dropped and others were revised, resulting in greater consistency in how patients, clinicians, and researchers interpreted the items’ meanings and improving the instrument’s content validity. Following additional revision and psychometric testing, the QLQ-CIPN20 could evolve into a gold-standard CIPN patient-reported outcome measure.

Rasch model-based testing of the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire–Chemotherapy-Induced Peripheral Neuropathy (QLQ-CIPN20) using Alliance for Clinical Trials in Oncology (Alliance) A151408 study data

“…Participants had difficulty distinguishing between the four response items, perhaps because they did not understand the intended meaning of the items, which reflects suboptimal content validity. This hypothesis is supported by our previous work testing the content validity of an abbreviated QLQ-CIPN version that excluded the suboptimal autonomic subscale and hearing loss items [26]. We reported that patients did not fully understand the item about foot drop, leading to the recommendation that this item be revised to ask about “trouble flexing the ankle because of weakness” instead of “difficulty walking because your feet dropped downwards.”…”

Overview and critical revision of clinical assessment tools in chemotherapy‐induced peripheral neurotoxicity

“…On the basis of these studies, it has been proposed that the sensory, motor, and autonomic subscales are not supported by evidence and that grading as an overall score provides better validity. Furthermore, there are a number of individual questions which have been demonstrated to be unclear to patients and lack appropriate psychometric robustness . Identified psychometric weaknesses warrant consideration to recalibrate the scale for future optimal use, including the use of 0 to 10 scaling …”

In Search of a Gold Standard Patient-Reported Outcome Measure for Use in Chemotherapy- Induced Peripheral Neuropathy Clinical Trials

“… 37 Six publications provide empirical evidence supporting the QLQ-CIPN20’s strong internal consistency and stability reliability, sensitivity, validity (content, structural, convergent, concurrent, and contrasting group), and responsiveness. 37 - 42 However, 2 studies provide conflicting evidence about the instrument’s structural validity. 39 , 42 Another study suggests that the instrument’s factor structure might be improved by item revisions that enhance the instrument’s content validity—the degree to which patients accurately interpret the intended meanings of the items.…”

“… 39 , 42 Another study suggests that the instrument’s factor structure might be improved by item revisions that enhance the instrument’s content validity—the degree to which patients accurately interpret the intended meanings of the items. 38 Thus, with minor revisions, it has the potential to become the gold-standard PRO measure in CIPN intervention trials.…”

“… 26 , 41 , 44 - 46 We found the QLQ-CIPN20 to be sensitive, reliable, and valid; however, items designed to evaluate autonomic neuropathy (dizziness, blurred vision, erectile dysfunction) and hearing loss compromised the instrument’s psychometric properties and were therefore removed. The revised questionnaire was tested for content validity—whether patient understanding of the items was consistent with the intended meanings—in the second study 38 (N = 25) using established cognitive interviewing techniques. 47 One additional item (using a car pedal) was removed; several items were retested after rewording to improve clarity.…”