Development and initial testing of an illness perception questionnaire for substitute decision makers of critically ill patients: a mixed methods study.

Abstract

Purpose: The Brief Illness Perception Questionnaire (Brief-IPQ) is used to quantify a patient's understanding of their condition. In critical care settings, substitute decision makers (SDMs) are tasked with making decisions on behalf of patients, but it can be difficult to evaluate how they perceive the patient's illness. We developed the Illness Perception Questionnaire for Substitute Decision Makers (IPQ-SDM) by adapting the Brief-IPQ and testing it with SDMs of patients in critical care.

Methods: In a mixed methods study, we modified the Brief-IPQ for the context of SDMs of critically ill patients using qualitative feedback. We then approached SDMs of critically ill patients three days after intensive care unit (ICU) admission to complete the IPQ-SDM in a prospective observational study. We calculated summary statistics for the individual questions and the total score. We evaluated prespecified associations between individual questions as well as the total score with clinical data that were abstracted from the patient chart.

Results: We received 44/50 (88%) complete responses with a mean (standard deviation [SD]) total score of 43 (11). Forty-six percent reported that they did not have any in-person visits due to the restrictions during the COVID-19 pandemic. The correlation of total score with the nine equivalents of nursing manpower score (NEMS) was 0.42 (P = 0.005) but it was not correlated (P = 0.07) with the multiple organ dysfunction score (MODS). The total mean (SD) score was higher (i.e., worse) for patients who died in hospital (48.2 [9.7], n = 13) than for those who were discharged alive (40.5 [10.2], n = 31, P = 0.03). Concern regarding the illness was correlated with MODS (Spearman correlation coefficient [ρ] = 0.39, P = 0.01) and NEMS (ρ = 0.29, P = 0.04).

Conclusion: We observed a modest level of correlation of the IPQ-SDM score with clinical measures in the adult ICU setting. Further research is needed before such a tool is broadly implemented.