E2 ModerateModerate confidencePEM not requiredLongitudinalPeer-reviewedReviewed
Standard · 3 min
Construct validity and temporal stability of the abridged 31-item Illness Behaviour Questionnaire.
Prior, Kirsty N, Bond, Malcolm J · Psychology & health · 2014 · DOI
Quick Summary
This study tested a questionnaire that measures how people think about their illness, including how much they believe they are ill, how worried they are about their health, and their overall mood. Researchers gave this questionnaire to 675 people—some healthy and some with chronic conditions like asthma, diabetes, chronic pain, or ME/CFS—and checked it again after 3 and 12 months. The questionnaire performed reasonably well and remained fairly stable over time.
Why It Matters
Understanding how ME/CFS patients perceive and think about their illness is important for both clinical care and research. This study includes ME/CFS patients in a diverse sample and validates a questionnaire that could be used to better understand psychological factors in chronic illness, which may help identify those at risk for prolonged illness or poor outcomes.
Observed Findings
The three IBQ-31 dimensions showed predicted correlations with validated measures of symptom attribution, cognitive distortion, and illness likelihood across all five samples.
Adequate test-retest reliability was observed over 3 months, indicating short-term stability of the questionnaire.
Greater score variability occurred over 12 months compared to 3 months, suggesting these illness perceptions may shift over longer periods.
71.6% of participants (n=483) completed the 3-month follow-up and 76.6% (n=517) completed the 12-month follow-up, indicating reasonable retention.
Inferred Conclusions
The IBQ-31 measures three theoretically relevant dimensions of illness perception that are relatively stable in the short term across diverse chronic illnesses including ME/CFS.
The questionnaire demonstrates adequate construct validity, showing it measures what it intends to measure in relation to existing psychological constructs.
Longer-term stability (12 months) is lower than short-term stability, suggesting these illness perceptions may naturally evolve or fluctuate over extended periods.
Remaining Questions
Do changes in these illness perception dimensions predict clinical outcomes or functional recovery in ME/CFS patients?
What are appropriate clinical cut-off scores for these dimensions, and do they differ across different chronic conditions?
What This Study Does Not Prove
This study does not prove that these psychological dimensions cause ME/CFS or worsen outcomes—it only shows that certain illness beliefs remain relatively stable over time. The research does not establish whether changing these beliefs through treatment would improve health outcomes. Additionally, the greater variability seen over 12 months suggests these measures may not be as reliable for long-term prediction.
Tags
Symptom:Fatigue
Method Flag:Exploratory OnlyMixed CohortWeak Case Definition
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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What factors drive the increased variability in scores between 3 and 12 months, and does this reflect genuine changes in illness perception or measurement unreliability?
Does the questionnaire differ in validity and stability when applied specifically to ME/CFS populations versus other chronic illnesses?