The measurement system, evolving since 1987, began with the creation of a generic core measure called the Functional Assessment of Cancer Therapy-General (FACT-G). The FACT-G (in version 4 since 1997) is a 27-item compilation of general questions divided into four primary QOL domains: Physical Well-Being, Social/Family Well-Being, Emotional Well-Being, and Functional Well-Being. It is considered appropriate for use with patients with any form of cancer, and has also been used and validated in other chronic illness conditions.

Validation of the core measure allowed for the evolution of multiple disease, treatment, condition, and other targeted measures. FACIT scales are constructed to complement the FACT-G, addressing relevant disease-, treatment-, or condition-related issues not already covered in the general questionnaire. Each is intended to be as specific as necessary to capture the clinically-relevant problems associated with a given condition or symptom, yet general enough to allow for comparison across diseases, and extension, as appropriate, to other chronic medical conditions.

The FACIT Measurement System now includes over 700 items, some of which have been translated into more than 80 languages. Assessment of any one patient is tailored so that the most-relevant questions are asked and administration time for any one assessment is usually less than 15 minutes. The majority of FACIT items have demonstrated face and content validity and were created with direct input from patients and expert clinicians.

More recently, FACIT has expanded its catalog of items to the FACIT Searchable Library, where one can create a custom form using the site’s Build-a-PRO function and include only those FACIT items most relevant to one’s study or purpose. While doing so does not instantly validate the custom composition, it does create an opportunity to select specific items relevant to the research question at hand, using content valid items that have undergone careful translation into other languages. It also allows for the opportunity to pursue validation of the assembled set of questions using standard questionnaire validation practice.

The practice of selecting an established, fixed FACIT questionnaire is still recommended for any investigator or clinician wishing to obtain a valid, interpretable score on the endpoints provided by that FACIT questionnaire.