Internal consistency reliability of the Revised Illness Perceptions Questionnaire: A systematic review and reliability generalization meta-analysis

Abstract

The Revised Illness Perception Questionnaire (IPQ-R) assesses patients’ perspectives of their illnesses. Original psychometric testing occurred in limited populations. The purpose of this reliability generalization meta-analysis was to: (1) estimate internal consistency reliability of each IPQ-R subscale, and (2) test moderators of these estimates. Web of Science was searched in July 2022 for articles citing the original IPQ-R paper that reported IPQ-R reliability data. Cronbach’s alphas (⍺) were pooled for each IPQ-R subscale using inverse variance weighting and DerSimonian and Laird estimation. Sixty-six studies met criteria. Overall pooled ⍺ estimates were acceptable: 0.71–0.87. Treatment control reliability was reduced among cardiac (⍺ = 0.68), diabetes/kidney disease (⍺ = 0.63), and mixed/other (⍺ = 0.66) samples; cyclical reliability was reduced in cancer (⍺ = 0.65) samples. Age, gender, and race were also significant moderators. Subscale reliability varied based on sample characteristics. Adapting IPQ-R subscales to account for sample variation could improve measurement of illness perception constructs.