Plain Language Summary

What is it about?

People living in disadvantaged neighborhoods often experience worse health outcomes, including higher rates of disease and lower quality of life. Understanding health-related quality of life in these populations is important for addressing health inequalities. However, a key question is whether measurement tools work the same way across different socioeconomic groups. If tools function differently based on where people live, this could create misleading comparisons and contribute to health inequity. This study examined whether the Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health questionnaire performs consistently across different levels of neighborhood disadvantage and other patient characteristics. The researchers proposed using differential item functioning—a method that detects whether people with the same health status respond differently based on their group membership—to determine if this widely used tool is appropriate for comparing quality of life across diverse populations.

How was the research conducted?

The researchers applied the concept that if a measurement tool is fair, people with the same health level should respond similarly regardless of their neighborhood status. They collected data from 158,685 adult patients who completed the Global Health questionnaire during primary care appointments in 2022. Using statistical methods, they examined whether questionnaire items functioned differently across groups defined by neighborhood disadvantage, age, sex, race, marital status, insurance type, and medical conditions. Neighborhood disadvantage was measured using the area deprivation index, which ranks neighborhoods based on socioeconomic factors. This method was chosen because it rigorously determines whether questionnaire items perform consistently across different populations while accounting for underlying health differences.

What were the results?

No differential item functioning was detected for any Global Health items across neighborhood disadvantage levels, age, sex, race, marital status, insurance type, or medical conditions. This means the questionnaire measures health-related quality of life consistently across all groups. Patients living in more disadvantaged neighborhoods had significantly worse health-related quality of life, with scores approximately 3.6 points lower on both mental and physical health compared to those in less disadvantaged neighborhoods. The largest differences were in physical health, quality of life, and social satisfaction items.

Why are the results important?

These results confirm that the Global Health questionnaire can fairly compare health-related quality of life across populations with different socioeconomic characteristics without introducing bias. Healthcare providers can confidently interpret scores from patients in different neighborhoods, knowing that differences reflect actual health status rather than measurement problems. Patients from all backgrounds benefit because their health-related quality of life can be accurately measured and compared. Long-term, these results support using the Global Health questionnaire in policies addressing socioeconomic health disparities, such as directing resources to disadvantaged areas.

What are the strengths and weaknesses of this study?

The main strength is the large sample of more than 150,000 patients and rigorous statistical methods examining measurement fairness across multiple patient characteristics. A limitation is that the study included only patients from one county within one health system, which may limit how broadly findings apply elsewhere. Future research could examine measurement fairness in other regions and investigate specific factors contributing to health inequalities between neighborhoods with different socioeconomic levels. 

^{Note: This content was created with assistance from artificial intelligence (AI) and has been reviewed and edited by ISPOR staff. For more information or for inquiries on ISPOR’s AI policy, click here or contact us at info@ispor.org.}