Exclusion Criteria as Measurements II: Effects on Utility Functions

Background. Researchers often justify excluding some responses in studies eliciting valuations of health states as not representing respondents’ true preferences. Here, we examine the effects of applying 8 common exclusion criteria on societal utility estimates. Setting. An online survey of a US nationally representative sample ( N = 1164) used the standard gamble method to elicit preferences for health states defined by 7 health domains from the Patient-Reported Outcomes Measurement Information System (PROMIS®). Methods. We estimate the impacts of applying 8 commonly used exclusion criteria on mean utility values for each domain, using beta regression, a form of analysis suited to double-bounded scales, such as utility. Results. Exclusion criteria have varied effects on the utility functions for the different PROMIS health domains. As a result, applying those criteria would have varied effects on the value of treatments (and side effects) that change health status on those domains. Limitations. Although our method could be applied to any health utility judgments, the present estimates reflect the features of the study that produced them. Those features include the selected health domains, standard gamble method, and an online format that excluded some groups (e.g., visually impaired and illiterate individuals). We also examined only a subset of all possible exclusion criteria, selected to represent the space of possibilities, as characterized in a companion article. Conclusions. Exclusion criteria can affect estimates of the societal utility of health states. We use those effects, in conjunction with the results of the companion article, to make suggestions for selecting exclusion criteria in future studies.

Measurement of Utility in Nonmelanoma Skin Cancer

Background: Quality of life is an important variable in assessing the impact of a condition on patients. The current literature shows a minimal effect of nonmelanoma skin cancer (NMSC) on patients' quality of life. This contrasts with our own experience. Given this disparity, we sought to perform an additional study in this area. Past studies have used multiattribute methods to assess quality of life. In contrast, the present study uses health utility methods, which rate a patient's quality of life from 0 to 1, with 1 representing perfect health. Methods: Forty-one patients were guided through two standardized scenarios using a standard gamble process with a trained interviewer. Health utility scores were determined for both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) using various NMSC treatment modalities. Results: All patients had health utility scores of 0.99 or higher. The standard gamble method showed no statistically significant differences in health utility scores for any treatment scenario for BCC or SCC using raw data comparisons. However, a modified standard gamble approach showed significantly higher health utility scores for both BCC and SCC treated using surgical modalities. Conclusion: Using the standard gamble health utility method in patients with BCC or SCC, it appears that these tumors have a minimal impact on the quality of life in the present study group. However, the results may simply reflect the poor sensitivity of the standard gamble health utility method to accurately assess quality of life changes in patients with NMSC. A modification of the standard gamble method did show that patients with NMSC associated surgical treatments with a better health outcome. New outcome measures need to be devised to accurately assess the toll of NMSC on patients.