Quality of Life Index (QLI)

1. Abstract

The Quality of Life Index (QLI), developed by Carol Estwing Ferrans and Marjorie Powers in 1985, is one of the most widely recognized, conceptually rigorous, and psychometrically sound instruments designed to evaluate health-related and global quality of life. Distinct from conventional self-report inventories that merely measure functional status or unweighted satisfaction, the QLI is rooted in an individualized value-weighting model. It operationalizes quality of life as a respondent’s perceived level of satisfaction with various aspects of life, weighted by the personal importance assigned to each of those aspects. The generic version of the instrument comprises 66 items partitioned symmetrically into two sections: 33 items assessing subjective satisfaction across life domains (Part I) and 33 parallel items assessing the personal importance of those exact domains (Part II). Responses are registered on 6-point Likert scales ranging from 1 (Very Dissatisfied / Very Unimportant) to 6 (Very Satisfied / Very Important).

Extensive factor-analytic studies have established four core latent dimensions underlying the instrument: Health and Functioning, Socioeconomic, Psychological/Spiritual, and Family. The instrument employs a sophisticated mathematical scoring algorithm that adjusts satisfaction scores by importance weights, yielding subscale and total quality-of-life scores ranging from 0 to 30, where higher scores signify superior perceived life quality. Psychometrically, the QLI exhibits exemplary internal consistency across diverse healthy, acute, and chronic populations (Cronbach’s alpha typically between .90 and .95 for the total instrument, and .75 to .90 for the subscales), robust test-retest reliability across 2- to 4-week intervals (ranging from .81 to .87), and robust convergent, discriminant, and known-groups validity. In addition to the generic edition, numerous validated disease-specific adaptations exist (e.g., cancer, cardiac, renal/dialysis, pulmonary, and diabetes versions), making the QLI a foundational assessment tool across nursing science, behavioral medicine, clinical oncology, and health services research worldwide.

2. Keywords

Quality of Life Index, QLI, Carol Estwing Ferrans, Marjorie Powers, Psychometrics, Health-Related Quality of Life, Importance Weighting, Patient-Reported Outcomes, Construct Validity, Factor Analysis, Chronic Illness Assessment

3. Authors

The Quality of Life Index was conceptualized, designed, and psychometrically validated by Carol Estwing Ferrans, PhD, RN, FAAN and Marjorie J. Powers, PhD, RN, FAAN at the University of Illinois at Chicago (UIC) College of Nursing.

Carol Estwing Ferrans, PhD, RN, FAAN is an internationally acclaimed nurse scientist, psychometrician, and Professor Emerita in the Department of Biobehavioral Nursing Science at the University of Illinois at Chicago College of Nursing. Dr. Ferrans also served as the Associate Dean for Research and the co-director of the Center for Population Health and Health Disparities at UIC. Her pioneering scholarship focuses on health equity, oncology outcomes, health disparities among underserved minority populations (particularly breast and cervical cancer screening and outcomes among African American and Hispanic women), and the conceptual and mathematical measurement of quality of life. Her seminal theoretical paper, Development of a Conceptual Model of Quality of Life (Ferrans, 1996), alongside her collaborative revision with Edward H. Wagner and others (the Ferrans et al. Model of Health-Related Quality of Life, 2005), fundamentally reshaped the interdisciplinary understanding of patient-reported outcomes in biomedical and behavioral research.

Marjorie J. Powers, PhD, RN, FAAN was a distinguished Professor of Medical-Surgical Nursing at the University of Illinois at Chicago College of Nursing. Her research interests encompassed hemodialysis patient outcomes, psychological adaptation to end-stage renal disease (ESRD), chronic illness management, and instrument development. Together with Dr. Ferrans, Dr. Powers established the philosophical, psychometric, and empirical foundations of the QLI, setting a new standard for individualized outcome measurement.

Contact Information for Instrument Inquiries:
Carol Estwing Ferrans, PhD, RN, FAAN
University of Illinois at Chicago, College of Nursing (M/C 802)
845 S. Damen Avenue, 7th Floor, Chicago, IL 60612, USA
Email: [email protected] | Official Web Portal: https://qli.grad.uic.edu/

4. Purpose

The fundamental purpose of the Quality of Life Index is to measure human quality of life through an individualized lens that honors subjective human values. Historically, health status metrics in clinical medicine and epidemiology focused overwhelmingly on objective indicators: survival duration, physiological biomarkers, organ clearance rates, and functional deficit tallies (e.g., Karnofsky Performance Scale, Activities of Daily Living indices). While these measures quantified physical morbidity and physical function, they failed to capture how patients actually experienced their lives, what they valued, and the emotional, social, and spiritual meanings they attached to their living circumstances.

Ferrans and Powers recognized that two individuals presenting with identical functional limitations or symptom profiles might experience radically different levels of overall life quality. For instance, a persistent physiological impairment (such as loss of athletic stamina or inability to engage in full-time employment) may induce profound distress in an individual whose life identity and values center entirely around occupational achievement and physical vigor. Conversely, the exact same impairment might have a negligible impact on the perceived well-being of an individual whose identity is predominantly anchored in family closeness, religious devotion, or intellectual hobbies. Consequently, any instrument that measures satisfaction without accounting for the idiosyncratic importance of each life domain risks serious measurement error.

The clinical and investigative rationales for the QLI encompass multiple dimensions:

• Individualized Clinical Assessment: In clinical practice—particularly in oncology, cardiology, nephrology, palliative care, and rehabilitation—the QLI identifies the specific domains of distress that disproportionately erode an individual’s well-being. By distinguishing between what is unsatisfactory yet trivial to the patient versus what is unsatisfactory and paramount, clinicians can prioritize supportive interventions that yield the greatest therapeutic benefit to the patient’s lived experience.
• Evaluation of Healthcare Interventions: In randomized controlled trials (RCTs) and comparative effectiveness research, the QLI serves as a highly sensitive patient-reported outcome measure (PROM). It assesses whether surgical procedures, pharmacotherapies, psychological counseling, or lifestyle interventions produce authentic, value-congruent enhancements in life quality rather than mere marginal physiological shifts accompanied by unmeasured iatrogenic burdens.
• Cross-Populational and Longitudinal Research: The QLI provides a standardized, mathematically normalized metric (scores calibrated from 0 to 30) that permits valid comparisons across diverse demographic groups, cultural communities, and clinical cohorts over time. Its robust structure enables tracking trajectories of adjustment, functional adaptation, disease progression, and treatment recovery across the lifespan.

5. Psychological Construct

The Quality of Life Index is predicated on an operational definition of quality of life as “a person’s sense of well-being that stems from satisfaction or dissatisfaction with the areas of life that are important to him/her” (Ferrans & Powers, 1985, p. 16). The construct rejects the reductionist view that QoL is merely the absence of disease, pain, or functional incapacity. Instead, quality of life is conceptualized as a multi-layered, multidimensional, dynamic construct reflecting cognitive appraisal, affective equilibrium, and personal value hierarchy.

Through systematic qualitative inquiry with patients and healthy individuals, exhaustive reviews of philosophical and psychological literature, and continuous empirical validation, Ferrans and Powers identified four primary subscales or latent dimensions comprising the global QLI construct:

1. Health and Functioning Subscale

This dimension encompasses an individual’s cognitive and experiential appraisal of their biological, somatic, and functional integrity. It captures not only health status and healthcare delivery but also the functional autonomy necessary to engage with the physical world. Items within this subscale assess satisfaction with and importance of:

• General health and medical care received.
• Freedom from physical pain and somatic distress.
• Energy levels available for everyday occupational and domestic tasks.
• Self-care agency (ability to care for oneself without relying on external assistance).
• Perceived personal control over one’s daily life and body.
• Chances of living as long as one desires (longevity expectations).
• Physical appearance, sexual function, and intimate biological life.

Crucially, this dimension does not simply inventory the presence of symptoms; it measures the extent to which the individual feels compromised or satisfied with their somatic capabilities relative to their expectations and value priorities.

2. Socioeconomic Subscale

The socioeconomic dimension operationalizes the material, environmental, social, and civic infrastructure that contextualizes human life. Quality of life is profoundly mediated by the security, dignity, and enrichment afforded by one’s living environment. This subscale measures appraisal regarding:

• Financial adequacy and the capacity to meet personal and household economic needs.
• Occupational status, job satisfaction (if employed), or adjustment to retirement/disability/unemployment.
• Educational attainment and opportunities for intellectual stimulation.
• Residential environment, including home, apartment, physical neighborhood, and community safety.
• Recreational life, leisure activities, and opportunities to do things for fun.
• Friendship networks and broader social relationships.
• Emotional support derived from individuals outside the nuclear family unit.
• Perceived usefulness to society and the capacity to contribute meaningfully to others.

3. Psychological/Spiritual Subscale

This subscale captures the internal psychological landscape, existential equilibrium, and spiritual grounding of the individual. It addresses the emotional and metaphysical parameters that buffer against psychological distress and confer life with meaning and purpose. It incorporates:

• Inner peace of mind and the subjective absence of excessive, debilitating worries.
• Religious faith, existential connection, or faith in God.
• Progress toward and realization of personal goals and aspirations.
• General subjective happiness and global satisfaction with one’s life as a whole.
• Self-esteem, self-acceptance, and positive appraisal of oneself in general.
• Optimism and perceived chances for a fulfilling, happy future.

4. Family Subscale

Recognizing that humans are embedded within primary relational systems, the family subscale measures the health, stability, and emotional reciprocity of the respondent’s primary kinship group. Family dynamics often represent both the greatest source of resilience and a primary domain of concern. This subscale specifically addresses:

• The somatic and emotional health of family members.
• The general happiness and functional well-being of the family unit.
• Relationships with children and satisfaction regarding their development and life path.
• The marital, romantic, or domestic partnership (spouse, lover, or partner).
• Emotional support received directly from the family network.
• The respondent’s perceived capacity to fulfill family roles and meet domestic responsibilities.

6. Theoretical Framework

The theoretical architecture of the Quality of Life Index is grounded in a synthesis of subjective well-being theory, psychological appraisal models, and nursing’s holistic conceptualizations of human health. Most notably, the QLI directly operationalizes and expands upon the seminal work of social scientists Angus Campbell, Philip E. Converse, and Willard L. Rodgers (1976), who demonstrated that overall life satisfaction is a function of satisfaction across multiple distinct life domains, weighted by the subjective importance that an individual assigns to each domain.

Campbell, Converse, and Rodgers posited that an individual’s evaluation of life quality involves a cognitive comparison process: individuals compare their perceived actual life circumstances with an internal standard, aspiration level, or ideal expectation. However, Ferrans and Powers identified a vital psychometric limitation in prior implementations of this paradigm. Most early researchers either summed raw domain satisfaction scores (assuming implicitly that all domains possess equal weight across all human beings) or utilized importance ratings merely as statistical regression weights in aggregate population models. Ferrans and Powers insisted that importance weighting must operate at the individual level before aggregation.

The philosophical and conceptual assumptions foundational to the QLI include:

1. Subjectivity as the Gold Standard: Quality of life is an inherently subjective phenomenon. External observers (including physicians, nurses, researchers, and family members) cannot reliably estimate a person’s life quality because they cannot inhabit that person’s subjective cognitive, emotional, and value framework.
2. Value Pluralism and Individual Prioritization: Human beings vary fundamentally in their value systems. For one person, physical prowess and career prestige are paramount, while spiritual peace and family cohesion are secondary. For another, physical health limitations are easily tolerated if spiritual serenity and domestic harmony are intact. An instrument that treats every item with equal mathematical weight imposes an arbitrary, culturally biased value hierarchy onto the respondent.
3. Cognitive Appraisal of Satisfaction: Satisfaction represents a cognitive evaluation of the congruence between personal expectations and actual reality. Dissatisfaction arises when a salient discrepancy exists between what is experienced and what is desired or expected.
4. The Ferrans Conceptual Model of Quality of Life (1996; Ferrans et al., 2005): Later codified into an overarching biomedical-behavioral model, Ferrans integrated Wilson and Cleary’s (1995) health-related quality of life model into a broader ecological system. The revised Ferrans et al. model delineates a continuum originating from: (a) biological function (cellular and organ-system integrity), which influences (b) symptoms (physical and psychological manifestations), which in turn impact (c) functional status (physical, social, and role performance), culminating in (d) general health perceptions, and ultimately resulting in (e) overall quality of life. Crucially, this pathway is continually moderated by both individual characteristics (genetics, personality, demographic variables, personal values) and environmental characteristics (social support, socioeconomic status, physical environment, healthcare access). The QLI sits at the apex of this model, measuring the ultimate integrated outcome of these interacting systems.

7. Validity

The Quality of Life Index has been subjected to exhaustive empirical validation across four decades, spanning hundreds of published studies, dozens of clinical conditions, and multiple cultural and linguistic contexts. The cumulative evidence provides unequivocal support for its construct, convergent, discriminant, and criterion-related validity.

Content and Face Validity

Initial content validity was rigorously established during instrument inception (Ferrans & Powers, 1985). The authors conducted extensive qualitative analyses of open-ended interviews with both healthy individuals and patients suffering from life-threatening chronic illnesses (such as end-stage renal disease undergoing hemodialysis). Patients were asked to define quality of life in their own terms, enumerate factors contributing to or detracting from their well-being, and prioritize life domains. Concurrently, an exhaustive review of philosophical, sociological, psychological, and medical literature was conducted. Items were drafted to mirror authentic patient vernacular and evaluated by panels of clinical experts and nurse scientists for clarity, representativeness, and exhaustiveness.

Construct Validity: Factorial and Known-Groups

Construct validity has been repeatedly demonstrated through known-groups comparisons. Ferrans and Powers (1992) demonstrated that the QLI discriminated with high statistical significance between healthy community-dwelling cohorts and medically compromised cohorts (e.g., dialysis patients, oncology patients, congestive heart failure patients). Healthy subjects scored significantly higher across total QLI and the Health and Functioning subscale than patients undergoing active cancer chemotherapy or chronic dialysis ($p < .001$). Furthermore, within clinical populations, the QLI demonstrates robust sensitivity to clinical gradients: patients with advanced metastatic malignancy (Stage IV) consistently report significantly lower health and functioning QLI scores than patients with early-stage disease (Stage I or II), and patients experiencing severe symptom clusters (e.g., severe cancer-related fatigue, chronic pain, severe dyspnea) exhibit marked decrements in total and domain-specific QLI scores.

Convergent and Discriminant Validity

Convergent validity is supported by strong, theoretically predictable correlations with established psychological and health status inventories:

• Life Satisfaction Measures: The QLI exhibits high positive correlations with Cantril’s Self-Anchoring Ladder ($r = .65$ to $.77$) and the Life Satisfaction Index-Z (LSI-Z; $r = .61$ to $.75$), demonstrating that it accurately captures global life satisfaction (Ferrans & Powers, 1985, 1992).
• Depressive Symptomatology: Scores on the QLI demonstrate moderate to strong negative correlations with validated depression scales, such as the Beck Depression Inventory (BDI) ($r = -.55$ to $-.68$) and the Center for Epidemiologic Studies Depression Scale (CES-D) ($r = -.60$ to $-.72$), demonstrating that higher perceived quality of life is inversely associated with affective distress.
• Generic Functional Status: Moderate correlations are observed with the Medical Outcomes Study Short Form-36 (SF-36) Physical Component Summary ($r = .45$ to $.58$) and higher correlations with the Mental Component Summary ($r = .60$ to $.71$), validating that while physical function contributes to QLI, the QLI measures a broader psychological and existential construct that is not redundant with mere physical performance.

Cross-Cultural and Transnational Validity

The QLI has undergone extensive cross-cultural validation and translation into more than 30 languages, including Spanish, Portuguese, Mandarin, Japanese, Korean, Italian, German, Persian, Turkish, and Arabic (Warnecke et al., 1996; Rafiei et al., 2014). Cross-cultural studies consistently reaffirm that the importance-weighting architecture is robust across diverse cultural matrices, effectively accounting for differential cultural values surrounding family obligations, religiosity, and community support.

8. Reliability

The psychometric reliability of the Quality of Life Index has been substantiated across extensive empirical investigations. Both internal consistency and stability across time (test-retest reliability) meet or exceed the rigorous criteria established for psychological and clinical outcome instruments.

Internal Consistency Reliability

Internal consistency has been calculated using Cronbach’s alpha coefficient across numerous distinct clinical and non-clinical cohorts. In the initial psychometric validation study with a sample of 349 hemodialysis patients and healthy subjects (Ferrans & Powers, 1985), the alpha coefficient for the total QLI was .93. Subsequent comprehensive reassessment with 756 subjects (Ferrans & Powers, 1992) yielded an overall alpha of .95.

Across specific subscales, internal consistency coefficients consistently demonstrate high reliability:

• Health and Functioning Subscale: $\alpha = .87$ to $.93$
• Socioeconomic Subscale: $\alpha = .78$ to $.86$
• Psychological/Spiritual Subscale: $\alpha = .82$ to $.90$
• Family Subscale: $\alpha = .66$ to $.78$

The somewhat lower, yet psychometrically acceptable, alpha for the Family subscale is attributable to its smaller item count (5 to 6 items) and the heterogeneous nature of kinship dynamics (e.g., relationships with children versus marital satisfaction).

Test-Retest Stability

Temporal stability has been confirmed in stable populations across multiple test-retest intervals. Ferrans and Powers (1985) administered the QLI to stable undergraduate nursing students with a two-week interval, obtaining a test-retest correlation coefficient of $r = .87$. In a subsequent assessment of hemodialysis patients tested four weeks apart during stable medical maintenance, the test-retest reliability coefficient was $r = .81$ (Ferrans & Powers, 1992). These coefficients confirm that the instrument possesses high stability over time while remaining responsive to meaningful changes in health status or environmental conditions.

Standard Error of Measurement and Responsiveness

The Standard Error of Measurement (SEM) for the total QLI score generally falls within the range of 1.2 to 1.8 points on the 0–30 scale. Studies examining the Minimal Clinically Important Difference (MCID) indicate that a change of 2.0 to 2.5 points in the total score or domain subscale scores represents a clinically meaningful alteration in perceived quality of life, a benchmark frequently utilized in statistical power calculations for clinical trials.

9. Factor Analysis

The underlying factorial structure of the Quality of Life Index was originally elucidated through Exploratory Factor Analysis (EFA) and subsequently confirmed through rigorous Confirmatory Factor Analysis (CFA) across diverse epidemiological and clinical samples.

Exploratory Factor Analysis (Ferrans & Powers, 1985, 1992)

In the foundational psychometric assessment (Ferrans & Powers, 1992), exploratory factor analysis utilizing principal factor extraction followed by orthogonal (Varimax) and oblique (Promax) rotations was performed on the weighted item scores from a diverse sample of 756 individuals (combining hemodialysis patients, cancer patients, cardiac rehabilitation attendees, and healthy individuals). Both the scree plot and Kaiser’s criterion (eigenvalues greater than 1.0) supported a four-factor solution accounting for approximately 85% of the total common variance.

The four empirically derived factors mapped onto the four conceptual subscales:

• Factor 1: Health and Functioning: Items loading heavily on this factor included health (.74), healthcare (.59), pain (.68), energy for daily tasks (.71), self-care agency (.65), control over life (.61), longevity expectations (.58), and sex life (.52).
• Factor 2: Socioeconomic: Items loading prominently included finances (.68), standard of living/home (.65), neighborhood (.61), job satisfaction (.59), leisure/fun activities (.58), friends (.54), education (.51), and utility to others (.49).
• Factor 3: Psychological/Spiritual: Items loading on this factor comprised peace of mind (.72), faith in God (.69), happiness in general (.76), life satisfaction (.74), personal goals (.63), worries (.55), and self-concept (.68).
• Factor 4: Family: High-loading items included family health (.71), family happiness (.78), children (.73), partner/spouse (.69), and emotional support from family (.64).

Confirmatory Factor Analysis (CFA) and Model Fit

Subsequent structural equation modeling across multiple cultural and patient populations has supported the second-order multidimensional model of the QLI, in which the four primary latent factors load onto a overarching global Quality of Life construct. Goodness-of-fit indices across several large-scale CFA studies consistently reveal acceptable to excellent fit: Comparative Fit Index (CFI) values ranging from .91 to .96, Tucker-Lewis Index (TLI) values exceeding .90, Root Mean Square Error of Approximation (RMSEA) values consistently between .045 and .062 (with 90% confidence intervals below .08), and Standardized Root Mean Square Residual (SRMR) values below .055. Measurement invariance testing across sex, age groups, and chronic illness versus healthy controls has demonstrated configural and metric invariance, confirming that the latent factors represent identical conceptual entities across heterogeneous populations.

10. Instrument / Measurement Tool

The Quality of Life Index is structured as a self-administered, paper-and-pencil or computerized questionnaire. A comprehensive breakdown of its structural characteristics and scoring protocol is detailed below:

• Test Type: Patient-Reported Outcome Measure (PROM) / Value-Weighted Self-Report Inventory.
• Target Population: Adults (aged 18 and older) across healthy community populations and diverse acute or chronic medical cohorts. (Validated disease-specific versions exist for cancer, cardiac, renal/dialysis, organ transplant, diabetes, and pulmonary conditions).
• Format & Structure: The generic instrument comprises exactly 66 items distributed into two balanced sections:
  • Part I: Satisfaction: 33 items measuring subjective satisfaction with specific life domains.
  • Part II: Importance: 33 parallel items measuring the personal importance attributed to those same domains.
• Administration Time: Approximately 10 to 15 minutes to complete both sections.
• Response Scale (Part I – Satisfaction): 6-point Likert scale:
  • 1 = Very Dissatisfied
  • 2 = Moderately Dissatisfied
  • 3 = Slightly Dissatisfied
  • 4 = Slightly Satisfied
  • 5 = Moderately Satisfied
  • 6 = Very Satisfied
• Response Scale (Part II – Importance): 6-point Likert scale:
  • 1 = Very Unimportant
  • 2 = Moderately Unimportant
  • 3 = Slightly Unimportant
  • 4 = Slightly Important
  • 5 = Moderately Important
  • 6 = Very Important
• Mathematical Scoring Algorithm: The QLI scoring algorithm is specifically engineered to ensure that dissatisfaction with an area deemed highly important produces the lowest possible score, while satisfaction with an area deemed highly important produces the highest possible score. Items rated as unimportant exert minimal influence on the aggregate score. The scoring proceeds through a four-step computational procedure:
  1. Recenter Satisfaction Scores: To create a bidirectional scale around zero, subtract 3.5 from each raw satisfaction rating (Part I):
     $$\text{Satisfaction}_{\text{centered}} = \text{Item}_{\text{Part I}} – 3.5$$
     This transformation converts raw scores (1, 2, 3, 4, 5, 6) into centered scores: -2.5, -1.5, -0.5, +0.5, +1.5, +2.5.
  2. Calculate Weighted Scores: Multiply each centered satisfaction score by its corresponding raw importance rating (Part II, which retains values from 1 to 6):
     $$\text{Weighted Item Score} = \text{Satisfaction}_{\text{centered}} \times \text{Item}_{\text{Part II}}$$
     This product ranges from a minimum of -15.0 (centered satisfaction -2.5 multiplied by importance 6) to a maximum of +15.0 (centered satisfaction +2.5 multiplied by importance 6).
  3. Domain and Total Aggregation: Sum the weighted item scores for all answered items within a specific subscale (or across the entire scale) and divide by the number of items answered in that subscale (or total scale) to obtain the average weighted score.
  4. Scale Normalization: Add 15 to the resulting average weighted score to eliminate negative numbers:
     $$\text{Final Subscale/Total Score} = \left( \frac{\sum \text{Weighted Item Scores}}{\text{Number of Answered Items}} \right) + 15$$
     This normalizes all final subscale scores and the overall total quality of life score onto a standardized range from 0.00 (lowest possible QoL) to 30.00 (highest possible QoL).
• Subscale Item Distribution:
  • Health and Functioning Subscale: Items 1, 2, 3, 4, 5, 6, 7, 11, 16, 17, 18, 25, 32.
  • Socioeconomic Subscale: Items 13, 15, 19, 20, 21, 22, 23, 24.
  • Psychological/Spiritual Subscale: Items 26, 27, 28, 29, 30, 31, 33.
  • Family Subscale: Items 8, 9, 10, 12, 14.

  (Note: In conditional items—such as Item 21 regarding employed status and Item 22 regarding unemployment/retirement/disability—respondents answer only the item applicable to their life situation, and the divisor in Step 3 is adjusted accordingly).

11. Permissions & Fee and Test Year

The Quality of Life Index was first published in 1985 by Carol Estwing Ferrans and Marjorie J. Powers. The instrument is copyrighted by Carol Estwing Ferrans.

Licensing and Accessibility: In dedication to advancing science, healthcare research, and clinical practice, the authors have made the Quality of Life Index (including all generic and disease-specific adaptations, along with detailed statistical scoring syntax for SPSS, SAS, and Stata) available free of charge for non-profit academic, research, and clinical assessment purposes. Researchers and clinicians are granted permission to download, administer, and reproduce the scale without paying licensing fees, provided that:

• The instrument is utilized in its authentic, validated form without unauthorized modifications to the item text, response format, or mathematical weighting protocol.
• Appropriate scholarly credit and formal bibliographic citations are attributed to Carol Estwing Ferrans and Marjorie Powers in all resulting publications, clinical reports, and academic presentations.
• Any commercial utilization, incorporation into proprietary digital platforms, or funded pharmaceutical industry trials requires explicit formal authorization from the copyright holder.

Official copies of the instruments, translated versions, and computerized scoring algorithms can be acquired directly from the official University of Illinois at Chicago web repository: https://qli.grad.uic.edu/.

12. References

Campbell, A., Converse, P. E., & Rodgers, W. L. (1976). The quality of American life: Perceptions, evaluations, and satisfactions. Russell Sage Foundation.

Ferrans, C. E. (1990). Development of a quality of life index for patients with cancer. Oncology Nursing Forum, 17(3 Suppl), 15–19. PubMed: 2349141

Ferrans, C. E. (1996). Development of a conceptual model of quality of life. Scholarly Inquiry for Nursing Practice: An International Journal, 10(3), 293–304. PubMed: 9009822

Ferrans, C. E., & Powers, M. J. (1985). Quality of Life Index: Development and psychometric properties. Advances in Nursing Science, 8(1), 15–24. https://doi.org/10.1097/00012272-198510000-00005

Ferrans, C. E., & Powers, M. J. (1992). Psychometric assessment of the Quality of Life Index. Research in Nursing & Health, 15(1), 29–38. https://doi.org/10.1002/nur.4770150106

Ferrans, C. E., Zerwic, J. J., Wilbur, J. E., & Larson, J. L. (2005). Conceptual model of health-related quality of life. Social Science & Medicine, 61(12), 2536–2548. https://doi.org/10.1016/j.socscimed.2005.04.032

Rafiei, N., Sharifian Sani, M., Rafiey, H., Behnampour, N., & Foroozesh, K. (2014). Reliability and validity of Persian version of “Quality of Life Index”. Journal of Mazandaran University of Medical Sciences, 24(116), 75–83.

Warnecke, R. B., Ferrans, C. E., Johnson, T. P., Chapa-Resendez, G., O’Rourke, D. P., Chavez, N., Freels, S., Schall, M., & Kelly, J. (1996). Measuring quality of life in culturally diverse populations. Journal of the National Cancer Institute Monographs, 1996(20), 29–38. https://doi.org/10.1093/oxfordjournals.jncimonographs.a024103

Wilson, I. B., & Cleary, P. D. (1995). Linking clinical variables with health-related quality of life: A conceptual model of patient outcomes. JAMA, 273(1), 59–65. https://doi.org/10.1001/jama.1995.03520250075037

13. Items of the Scale (Questionnaire)