Utility of the Brief Illness Perception Questionnaire to Monitor Patient Beliefs in Systemic Vasculitis

Abstract

Objective: To assess the validity and clinical utility of the Brief Illness Perception Questionnaire (BIPQ) to measure illness perceptions in multiple forms of vasculitis.

Methods: Patients with giant cell arteritis (GCA), Takayasu arteritis (TA), antineutrophil cytoplasmic antibody-associated vasculitis (AAV), and relapsing polychondritis (RP) were recruited into a prospective, observational cohort. Patients independently completed the BIPQ, Multidimensional Fatigue Inventory (MFI), Medical Outcomes Study 36-item Short Form survey (SF-36), and a patient global assessment (PtGA) at successive study visits. Physicians concurrently completed a physician global assessment (PGA) form. Illness perceptions, as assessed by the BIPQ, were compared to responses from the full-length Revised Illness Perception Questionnaire (IPQ-R) and to other clinical outcome measures.

Results: There were 196 patients (GCA = 47, TA = 47, RP = 56, AAV = 46) evaluated over 454 visits. Illness perception scores in each domain were comparable between the BIPQ and IPQ-R (3.28 vs 3.47, P = 0.22). Illness perceptions differed by type of vasculitis, with the highest perceived psychological burden of disease in RP. The BIPQ was significantly associated with all other patient-reported outcome measures (rho = |0.50-0.70|, P < 0.0001), but did not correlate with PGA (rho = 0.13, P = 0.13). A change in the BIPQ composite score of ≥ 7 over successive visits was associated with concomitant change in the PtGA. Change in the MFI and BIPQ scores significantly correlated over time (rho = 0.38, P = 0.0008).

Conclusion: The BIPQ is an accurate and valid assessment tool to measure and monitor illness perceptions in patients with vasculitis. Use of the BIPQ as an outcome measure in clinical trials may provide complementary information to physician-based assessments.

Keywords: Takayasu arteritis; cohort studies; giant cell arteritis; vasculitis.

Figure 1.. Comparison of the BIPQ and IPQ-R domains mean and standard deviation to determine comparability of the two measures.

(A) Mean illness perception domains scores did not significantly differ between the BIPQ and the IPQ-R, indicating comparable accuracy between the two assessment tools. (B) Mean standard deviations for illness perception domain scores were significantly lower for the IPQ-R compared to the BIPQ, indicating that illness perceptions are measured with greater precision by the IPQ-R.

Figure 2.. Distribution of BIPQ composite scores by type of vasculitis.

Perceived psychological burden of illness as assessed by the composite BIPQ score differed significantly across the four forms of vasculitis. Patients with relapsing polychondritis (RP) perceived the greatest psychological burden of illness. Analysis of variance test with post-hoc Tukey comparisons. *p<0.05 ****p<0.0001. GCA = giant cell arteritis; TAK = Takayasu’s arteritis; AAV = ANCA-associated vasculitis.

Figure 3.. BIPQ associations with patient- and physician-reported measures.

(A) Illness perceptions as measured by the composite Brief Illness Perception Questionnaire (BIPQ) were significantly correlated to other patient-reported outcome measures, including patient global assessment (PtGA: r = 0.70, p < 0.01), fatigue (MFI: r = 0.63, p < 0.01), metal health (SF-36 MCS: r = −0.50, p < 0.01), and physical health (SF-36 PCS: r = −0.60, p < 0.01). (B) SF-36 PCS was the only patient-reported outcome significantly associated with physcian assesment of disease activity (PhGA) (r = −0.24, p = 0.01). (C) Illness perceptions as measured by the BIPQ were not significantly correlated with PhGA (r = 0.13, p = 0.13).

Figure 4.. Change in illness perceptions over time and relationship to other patient- and physician- reported disease assessments.

(A) Composite BIPQ scores were categorized as worse (increased by 7 points or greater), improved (decreased by 7 point or greater) or unchanged. Using this threshold, change in BIPQ was significantly associated with concomitant change in patient global assessment scores over time. (B) In contrast, change in composite BIPQ scores by 7 or greater was not associated with concomitant change in physician global assessment scores over time. (C) Change in measures of fatigue (MFI) and illness perception (BIPQ) were significantly correlated over time.