Disutility represents the decrease in quality of life due to a particular symptom or complication. These values are typically expressed as negative numbers to reflect the adverse impact of the symptom or disease on a patient’s well-being. Disutility values are often calculated by subtracting the utility value (quality of life) of a health state with the symptom or complication from the utility value of a similar health state without it.

For example, if the utility of a health state without a complication is 0.8 and with the complication is 0.6, the disutility of the complication would be 0.8 – 0.6 = 0.2. Disutilities can be combined to assess the overall impact on a patient’s quality of life, usually through additive means, though sometimes multiplicative combinations are used. However, care must be taken in combining disutilities, as the sum of individual disutilities might not always equal the disutility of the combined health states independently.

Accurate calculation and combination of disutilities are essential for comprehensive health economic evaluations, as they provide critical insights into the burden of diseases and the potential benefits of interventions aimed at reducing these burdens.