Health-related Quality of Life, Psychological Distress and Fatigue in Metastatic CRPC Patients Treated With Radium-223

Measured with the European Organization for Research and Treatment of Cancer (EORTC) core QoL questionnaire (QLQ-C30). All items are rated on a 4-point Likert-type response scale of 1 ("not at all") to 4 ("very much"), with the exception of the global health status scale items, which are rated from 1-7. Each subscale will be linearly transformed to a 0-100 scale, according to the EORTC scoring manuals. For the functional and global scales, high scores indicate high level of functioning. For the symptom scales, high scores indicate high symptom burden. Clinically relevant changes (CRCs) in EORTC scores are defined as small (5-10 points), moderate (10-20 points), or large (>20 points).

Measured with the European Organization for Research and Treatment of Cancer (EORTC) bone metastases module (BM-22). All items are rated on a 4-point Likert-type response scale of 1 ("not at all") to 4 ("very much"). Each subscale will be linearly transformed to a 0-100 scale, according to the EORTC scoring manuals. For the functional and global scales, high scores indicate high level of functioning. For the symptom scales, high scores indicate high symptom burden. Clinically relevant changes (CRCs) in EORTC scores are defined as small (5-10 points), moderate (10-20 points), or large (>20 points).

Measured with the Brief Pain Inventory Short Form (BPI-SF). The pain severity items are rated on 0-10 scales, with 0 indicating "no pain" and 10 indicating "worst possible pain". Clinically relevant pain is defined as a score of ≥4 on the average pain severity scale.

Measured with the Hospital Anxiety and Depression Scale (HADS). The HADS contains a 7-item anxiety and a 7-item depression subscale. All items are scored on a 4-point Likert-scale ranging from scores 0 ('never') to 3 ('almost always'). A total score of 11 or higher indicates psychological distress. The clinically relevant chage in HADS subscale scores is defined as 1.5 points change, and 3 points change for the total HADS score.

Measured with the Checklist Individual Strength - Fatigue subscale (CIS-Fatigue). The CIS-Fatigue contains 8 items, and each item is scored on a 7-point Likert scale ranging from "Yes, that is true" to "No, that is not true". A score of 35 or higher on the subscale fatigue severity indicates severe feelings of fatigue.

Defined as the time between the first radium-223 injection and either death from any cause or the last follow-up

Number of radium-223 injections

Individual responses are classified based upon similar patterns in health-related quality of life, according to the EORTC QLQ-C30 summary score. Summary scores will be classified as <60 (low), 60-80 (intermediate) and >80 (high). Changes in summary scores over time will be classified as deteriorated, stable low (low at all time points), stable intermediate, stable high, improved and fluctuating.