Are Patient-Reported Outcomes of Physical Function a Valid Substitute for Objective Measurements?

Abstract

BackgroundPhysical function is important for defining treatment strategies in patients with cancer and can be estimated using patient-reported outcomes (pros). Although pros are subjective, physical activity and fitness can be tested objectively with adequate, but more labour-intensive methods that are rarely used in daily clinical practice. To determine whether pros for physical function (pro-pf) accurately predict physical function, we studied their interrelationships with objective measures of physical activity and fitness in patients with cancer who had completed cancer treatment, including adjuvant or neoadjuvant chemotherapy or autologous stem-cell transplantation.MethodsBaseline data from the react (Resistance and Endurance Exercise After Chemotherapy) and exist(Exercise Intervention After Stem-Cell Transplantation) studies were evaluated. In those studies, the effects of an exercise intervention on physical fitness, fatigue, and health-related quality of life in patients with cancer shortly after completion of chemotherapy or stem-cell transplantation were studied. Interrelationships between pro-pf (physical function subscale of the European Organisation for Research and Treatment of Cancer 30-question core Quality of Life Questionnaire), physical activity (accelerometer), and cardiorespiratory fitness (peak oxygen uptake) were assessed using univariable and multivariable multilevel linear mixed-model analyses.ResultsAfter adjustment for age, sex, and body mass index, the pro-pf was significantly associated with physical activity (β = 1.75; 95% confidence interval: 1.08 to 2.42) and cardiorespiratory fitness (β = 0.10; 95% confidence interval: 0.06 to 0.13). Standardized coefficients were 0.28 and 0.26 respectively, indicating a weak association.ConclusionsThe pro-pf is only weakly associated with objective physical activity and fitness evaluation in patients after curative treatment for cancer. The pro-pf cannot, therefore, be used in clinical practice as a substitute for objective measures of physical function.

Measuring What Is Meaningful in Cancer Cachexia Clinical Trials: A Path Forward With Digital Measures of Real-World Physical Behavior

“… 77 There is mixed evidence of associations between PROs and objective measures of physical function in cancer—some studies reported strong associations, 78 , 79 whereas others reported modest 80 to no associations. 81 , 82 This may be in part because of the nature of the PROs that are focused on global well-being that do not capture functional independence or real-world behavior of individuals, although they are important to patients. This supports the idea that PROs may need to be complemented by objective measures to provide a holistic picture of physical function, with a low burden on patients.…”

“…This supports the idea that PROs may need to be complemented by objective measures to provide a holistic picture of physical function, with a low burden on patients. 81 , 82 …”

“… 70 They also tend to have modest association with subjective measures. 80 , 81 Still, the assessments have some value, just like the PROs or ClinROs, because patients care about being able to exercise and do weight-bearing activities in their daily life. Therefore, they may be best complemented by digital measures that capture real-world behavior with the help of DHTs.…”

The Path Forward for Digital Measures: Suppressing the Desire to Compare Apples and Pineapples

“…Associations of PROMs and digital measures have been mixed. While objective wearable data often demonstrate lower associations with PROM scores of purported similar concepts (sleep quality, scratching) than layman expectations would posit [42][43][44][45], other areas have found PROMs to be highly aligned with sensor-derived variables [46,47]. For instance, Bahej et al [47] used objective measures to forecast PROs and achieved accuracies of around 70-80% for predicting subjectively reported mobility.…”