Hypertension specific patient-reported outcome measure. Part II: validation survey and item selection process

Abstract

Aim. Improvement of the health-related quality of life (HRQoL) is one of the basic principles of value-based medicine. HRQoL could be assessed by the patient-reported outcome measures (PROMs) also in case of arterial hypertension (HTN). However for HTN patients only generic PROMs are still used. Previously the group of experts had created the primary version of HTN-specific PROM. The purpose of the second part was to conduct a validation survey and to select the items in a statistically-based manner. Material and methods. Validation survey was conducted in a large multidisciplinary center among patients with HTN stages 1-3 and healthy volunteers. Inclusion criteria were age >18 years old, ability to understand or complete the scale themselves, absence of significant illness requiring hospitalization. The items were selected according to the principles of classical test theory (CTT) and item response theory (IRT). The criteria for CTT were sensitivity (standard deviation and coefficient of variation with corresponding confidence intervals), representativeness (item-total Pearson’s correlation coefficient), internal consistency (Cronbach’s a coefficient). In IRT analysis two methods were adopted — value of four degrees of difficulty and the discrimination estimate. Each question was evaluated according to 8 criteria. An item was considered for selection when it was retained by ≥4 criteria. The expert panel considered practical significance of each item. Results. A total of 430 questionnaires were distributed and 407 (94,7%) of them were returned completed (from 359 hypertensive patients, mean age 62,3±11,7 y.o.; 48 healthy volunteers, mean age 38,8±10,5 y.o.). The average time for PROM filling was 24±4,2 minutes. Of 163 questions, 27 met all 8 criteria and 3 questions did not match any. Of the 36 HTN-specific questions, 11 matched ≥5 criteria and in the generic part there were 87 questions (33 in the PHY domain, 35 for PSY, 8 for SOC, 11 for THER). The symmetric distribution of criteria was seen in 25 questions, of which 11 were evaluated by experts and then retained. For 40 questions, <4 eligibility criteria were recorded, of which 9 were retained after expert review. The PROM draft contained 80 questions (19 questions in the physiology domain, 22 in psychology, 6 in social, 13 in therapy, 20 items are HTN-specific). Conclusion. The methods of CTT and IRT allowed to reduce the PROM volume without losing the semantic richness and the need to reorganize the conceptual structure. The next step is the validation of the scale.