Representativeness of the Patient-Reported Outcomes Measurement Information System Internet panel

Abstract

Objectives: To evaluate the Patient-Reported Outcomes Measurement Information System (PROMIS), which collected data from an Internet polling panel, and to compare PROMIS with national norms.

Study design and setting: We compared demographics and self-rated health of the PROMIS general Internet sample (N=11,796) and one of its subsamples (n=2,196) selected to approximate the joint distribution of demographics from the 2000 U.S. Census, with three national surveys and U.S. Census data. The comparisons were conducted using equivalence testing with weights created for PROMIS by raking.

Results: The weighted PROMIS population and subsample had similar demographics compared with the 2000 U.S. Census, except that the subsample had a higher percentage of people with higher education than high school. Equivalence testing shows similarity between PROMIS general population and national norms with regard to body mass index, EQ-5D health index (EuroQol group defined descriptive system of health-related quality of life states consisting of five dimensions including mobility, self-care, usual activities, pain/discomfort, anxiety/depression), and self-rating of general health.

Conclusion: Self-rated health of the PROMIS general population is similar to that of existing samples from the general U.S. population. The weighted PROMIS general population is more comparable to national norms than the unweighted population with regard to subject characteristics. The findings suggest that the representativeness of the Internet data is comparable to those from probability-based general population samples.

Figure 1. Equivalence testing for general health item comparisons between PROMIS samples and national norms (MEPS, NHANES, BRFSS)

note: The horizontal bars depict confidence intervals (CI). CI for equivalencies (90% CI) are contained in the interval with endpoints −10% and +10% of the corresponding national norm means.

Figure 2. Equivalence testing for comparisons of EQ-5D health index score and Body Mass Index (BMI) between PROMIS samples and national norms

note: The horizontal bars depict confidence intervals (CI). CI for equivalencies (90% CI) are contained in the interval with endpoints −10% and +10% of the corresponding national norm means.