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Assessing Immune Fitness in Oncological Rehabilitation—Validity and Responsiveness of the Immune Status Questionnaire and Single-Item Scale
by
, , and
Anne M. S. de Hoop
1,2,3,*
,
Johanna A. Eggink
1,4,
Cindy Veenhof
1,3,
Cyrille A. M. Krul
2,
Jelle P. Ruurda
5,
Raymond H. H. Pieters
2,6 and
Karin Valkenet
1,3 1
Research Group Innovation of Human Movement Care, Research Center for Healthy and Sustainable Living, HU University of Applied Sciences Utrecht, 3583CS Utrecht, The Netherlands
2
Research Group Innovative Testing in Life Sciences and Chemistry, Research Center for Healthy and Sustainable Living, HU University of Applied Sciences Utrecht, 3583CS Utrecht, The Netherlands
3
Department of Rehabilitation, Physiotherapy Science & Sport, University Medical Center Utrecht, Utrecht University, 3584CX Utrecht, The Netherlands
4
Physiotherapy Science, Program in Clinical Health Sciences, University Medical Center Utrecht, Utrecht University, 3584CG Utrecht, The Netherlands
5
Department of Surgery, University Medical Center Utrecht, Utrecht University, 3584CX Utrecht, The Netherlands
6
Institute for Risk Assessment Sciences (IRAS)-Toxicology, Population Health Sciences, Faculty of Veterinary Sciences, Utrecht University, 3584CM Utrecht, The Netherlands
*
Author to whom correspondence should be addressed.
Curr. Oncol. 2026, 33(7), 415; https://doi.org/10.3390/curroncol33070415
Submission received: 14 May 2026
/
Revised: 3 July 2026
/
Accepted: 8 July 2026
/
Published: 10 July 2026
Simple Summary
Immune fitness describes how well the body can respond to health challenges and maintain a balanced immune system. Assessing immune fitness may help healthcare professionals to better tailor rehabilitation programs for people recovering from cancer. In this study, we evaluated two brief questionnaires that measure immune fitness in individuals participating in cancer rehabilitation during or shortly after treatment. The questionnaires showed some meaningful associations with fatigue and physical functioning, which suggests that perceived immune fitness may be linked to important aspects of recovery. However, associations with other health measures were weaker than expected, and the questionnaires were not able to adequately detect changes over time. Although participants generally reported relatively high levels of immune fitness, these findings indicate that these two questionnaires may not fully reflect the complex immune-related challenges experienced by cancer survivors. Future research should focus on developing more appropriate tools for this population.
Abstract
Background: Immune fitness (IF) reflects the body’s ability to mount appropriate immune responses. Monitoring IF could improve tailored treatment in oncological rehabilitation. The Immune Status Questionnaire (ISQ) and the Single-Item Scale (SIS) were developed to assess IF, but their clinimetric properties in cancer rehabilitation remain unknown. Aims: To evaluate the construct validity, responsiveness, and correlation between the ISQ and the SIS in oncological rehabilitation. Methods: The study population included people participating in oncological rehabilitation during or within one year after medical treatment. Data were collected prospectively via questionnaires. Construct validity and responsiveness were assessed through predefined hypotheses, including correlations with fatigue, sleep problems, malnutrition risk, activity impairment, and physical functioning. Results: In total, 97 individuals were included in the analyses. Median ISQ and SIS scores were 8/10 and 7/10, respectively. Correlations ranged from r = −0.21 to r = −0.50. Only the SIS correlations with fatigue and physical functioning, and the ISQ correlation with fatigue, met the predefined thresholds. Responsiveness hypotheses were not confirmed. Conclusions: The ISQ and the SIS demonstrated low construct validity and responsiveness in this population. IF scores were higher than expected. Correlations showed links between fatigue, physical functioning, and IF. Future research should develop tools tailored to the complex immune disturbances experienced by cancer survivors.
Keywords:
immune fitness; immune system; physical therapy; cancer
