Support for the Reliability and Validity of the National Institutes of Health Impact Stratification Score in a Sample of Active-Duty U.S. Military Personnel with Low Back Pain

Published in: Pain Medicine, Volume 22, Issue 10, pages 2185-2190 (October 2021). doi: 10.1093/pm/pnab175

by Ron D. Hays, Maria Orlando Edelen, Anthony Rodriguez, Patricia M. Herman

Read More

Access further information on this document at Pain Medicine

This article was published outside of RAND. The full text of the article can be found at the link above.


Evaluate the Impact Stratification Score (ISS) measure of low back pain impact that assesses physical function, pain interference, and pain intensity.


Secondary analyses of a prospective comparative effectiveness trial of active-duty military personnel with low back pain.


A Naval hospital at a military training site (Pensacola, Florida) and two military medical centers: 1) Walter Reed National Military Medical Center (Bethesda, Maryland); and 2) San Diego Naval Medical Center.


The 749 active-duty military personnel had an average age of 31 years, 76% were male, and 67% were white.


Participants completed questionnaires at baseline, 6 weeks later, and 12 weeks later. Measures included the ISS, Roland-Morris Disability Questionnaire (RMDQ), PROMIS-29 v1.0 satisfaction with social role participation scale, and single-item ratings of average pain, feeling bothered by low back pain in the past week, and a rating of change in low back pain.


Internal consistency reliability for the ISS was 0.92-0.93 at the three time points. The ISS correlated 0.75 to 0.84 with the RMDQ, 0.51 to 0.78 with the single-item ratings, and -0.64 to -0.71 with satisfaction with social role participation. The ISS was responsive to change on the three single items. The area under the curve for the ISS predicting improvement on the rating of change from baseline to 6 weeks later was 0.83.


This study provides support for the reliability and validity of the ISS as a patient-reported summary measure for acute, subacute, and chronic low back pain. The ISS is a useful indicator of low back impact.

Research conducted by

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.