Estimates of utility weights in hemophilia: implications for cost-utility analysis of clotting factor prophylaxis

Abstract

Estimates of preference-weighted health outcomes or health state utilities are needed to assess improvements in health in terms of quality-adjusted life-years. Gains in quality-adjusted life-years are used to assess the cost–effectiveness of prophylactic use of clotting factor compared with on-demand treatment among people with hemophilia, a congenital bleeding disorder. Published estimates of health utilities for people with hemophilia vary, contributing to uncertainty in the estimates of cost–effectiveness of prophylaxis. Challenges in estimating utility weights for the purpose of evaluating hemophilia treatment include selection bias in observational data, difficulty in adjusting for predictors of health-related quality of life and lack of preference-based data comparing adults with lifetime or primary prophylaxis versus no prophylaxis living within the same country and healthcare system.

Keywords:

• health utilities
• hemophilia
• prophylaxis
• quality-adjusted life-years
• quality of life

Disclaimer

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• The hemophilia cost–effectiveness literature has struggled to assess the value of continuous prophylaxis versus on-demand or episodic treatment.

• Accurate estimates of quality-adjusted life-years associated with different hemophilia management strategies, including different prophylaxis protocols, are needed to assess cost-utility.

• Although indirect generic preference-based instruments such as EQ-5D, SF-6D, Health Utilities Index-2 and Health Utilities Index-3 allow researchers to estimate utility weights, studies using different instruments often find substantially different estimates and it is not clear which ones are most useful.

• Studies have reported small cross-sectional differences in utility scores by hemophilia severity, particularly if one controls for confounding by HIV infection.

• Males in countries where primary prophylaxis has been long promoted have significantly better utility scores than males in countries with less use of prophylaxis.

• The timing of the start of prophylaxis, schedule of prophylaxis, severity of the disease, type of treatment and presence of complications such as joint disease or an inhibitor may play an important role in health-related quality of life.

• It could be helpful to estimate the association of treatment type with utility values using a fixed effects (dummy variable) model to control for country of residence because currently, there is no published evidence on difference in utility weights in severe hemophilia by timing or duration of use of prophylaxis within national populations.

• Future research should focus on longitudinal assessments using registry data and on including controls for confounding by co-morbid conditions (e.g., HIV or hepatitis C virus infection).

• Disease-specific health-related quality of life instruments may be more sensitive than generic instrument in detecting relatively small but clinically important differences in outcomes while measuring a narrow aspect of functioning related to a disease. The development of mapping algorithms to derive utility measures from condition-specific instruments require vetting to demonstrate reliability and value.