WORCESTER, MA, January 8, 2016 — Researchers at UMass Medical School and JWRG have published results that open up a new pathway to disease-specific quality of life (QOL) impact measurement, as reported in a special issue of International Journal of Statistics in Medical Research (IJSMR) on methods for estimating treatment effects for persons with multiple chronic conditions (MCC). This study, sponsored by the Agency for Healthcare Research and Quality (AHRQ), evaluated alternative approaches to measuring disease-specific impact across people who reported MCC. Results demonstrated the feasibility of JWRG’s new approach to individualized disease impact measurement
The QOL Disease-specific Impact Scale (QDIS®), which standardizes content and scoring across diseases, is central to JWRG’s new measurement approach. Previous research has shown that calculating a single QDIS impact score across multiple QOL content areas was justified, that standardization of QDIS content and scoring across diseases was psychometrically sound, and that QDIS administration was practical (10-15 seconds per patient per disease). The following question remained: are QOL impact attributions to a specific disease valid in the presence of multiple chronic conditions?
Although disease attribution often is addressed in single-disease studies, this question has rarely been examined in the presence of MCC. In the IJSMR study, the validity of responses to multiple disease-specific measures (symptoms, severity ratings, QDIS ratings) was tested in 4,480 US adults, all of whom were known to have a pre-identified condition. Respondents also provided information on disease severity and QDIS disease impact for every comorbid condition (out of 35) they reported; three fourths had three or more conditions. The study explored the extent to which respondents with MCC could make valid attributions to specific conditions when reporting disease impact. In other words, could a respondent with both diabetes and angina distinguish the impact of each disease on their quality of life? Across more than 900 tests, more than 9 out of 10 results showed that respondents could make these distinctions, which supported the validity of QDIS disease impact measures. Exceptions were most often observed for comorbid conditions within the same general clinical area; for example, asthma and COPD.
To the best of our knowledge, this was the first large-scale attempt at validating disease-specific QOL impact attributions across multiple disease groups. Results indicated that persons with MCC generally could estimate the QOL burden of specific conditions. These findings also support pursuit of a second aim of the AHRQ study, which was to evaluate a summary disease-specific QOL impact score that combines QDIS ratings across MCC. Results being prepared for publication suggest that such a measure might be useful for case-mix adjustment in comparative effectiveness research, particularly in studies of patient-reported outcomes. Individualized estimates of the QOL impact of specific conditions for patients with MCC may also help clinicians better understand the reasons for reduced overall physical or emotional health.