Illness Index

The Illness Index questionnaires efficiently measure an individual’s appraisal of Health-Related Quality of Life (HR-QOL), otherwise know as “illness burden.”

The Illness Index is completed by the patient to obtain their appraisal of the impact of a disease, congenital disorder or injury on their life. The Illness Index – Healthcare Provider (II-HCP) is intended for the physician, nurse or other healthcare provider who is familiar with the patient and their disorder to provide a professional assessment of the likely HR-QOL concerns from the disorder. The Illness Index – Observer is intended for a person who is familiar with the patient (usually a family member) to provide a perspective of the patient’s illness experience outside of the clinical care setting. The Treatment Index provides the patient appraisal of HR-QOL concerns related to a treatment. 

Research and professional consensus has long established that the evaluations people construct of their illness experience has implications for recovery from disease, longevity, medical compliance and mood and adjustment. In 1990, the NIH Consensus Statement on surgery for epilepsy stated that in addition to showing a decline in the number of seizures, the effectiveness of neurosurgery “…should use general measures of outcome that would take advantage of validated and quantitative methods to assess the quality of life.” 

HR-QOL may be important when dealing with limited or declining healthcare dollars or resources. Policy makers, insurers, healthcare professionals and professional organizations (see the sidebar comments) increasingly emphasize quality of life assessments and may use a cost-benefit analysis to make treatment and economic decisions about access to expensive care or drugs that may prolong life but provide unknown quality of life gains. Thus, assessing HR-QOL should be part of a medical assessment. HR-QOL data are also ideal for inclusion into electronic health records.

When a multiple-informant assessment using the Illness Index measures is available, a clinically rich set of hypotheses emerges. The manual provides information about these hypotheses and guidance on how to clinically follow up on patient responses. Different profiles can be associated with a variety of patient behaviors that can impact care and potentially patient health. An example is provided below.

For example, when a patient is reporting below expected illness impact appraisal compared to the provider assessment and a below average appraisal for that condition, several hypotheses can be generated from this profile:

Positive Implications
Good patient coping skills
Good social support
Disorder does not impact patient lifestyle

Negative Implications
Patient is in denial, lacks awareness or minimizes illness impact
Poor patient knowledge of the disorder
Limited healthcare provider knowledge of the patient beyond the medical variables

Disease Variables
Brief period living with the disorder
Mild illness manifestations
Patient may have reduced incentive to comply with treatment
Slow onset without full manifestation of disease features


The Index Index scales are presently available at no cost.
Click the folder to download the Illness Index manual and scales

The Illness Index questionnaires are intended for qualified professionals and should not be used without appropriate professional training and other sources of information to make clinical decisions.

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