Psychometric properties of the FACT-M questionnaire in patients with Merkel cell carcinoma

Abstract

Background: No validated disease-specific questionnaires exist to capture health-related quality of life (HRQoL) in patients with Merkel cell carcinoma (MCC). The Functional Assessment of Cancer Therapy - Melanoma (FACT-M) is validated in patients with melanoma, which shares many similarities with MCC. This paper reports the psychometric properties of the FACT-M in the metastatic MCC population.

Methods: Data were collected as part of a single-arm, open-label, multicenter trial involving patients with metastatic MCC who had failed at least one previous line of chemotherapy. FACT-M and EQ-5D were administered at baseline, Week 7, Week 13, and Week 25. An optional interview was administered at the same time points. MCC-specific FACT-M scores were derived following a combined quantitative and qualitative approach. Reliability and construct validity of original and additional MCC-specific FACT-M scores were assessed at baseline. Capacity to detect change in tumor size was assessed from baseline to Week 7. Minimally important differences (MIDs) were computed using distribution and anchor-based methods.

Results: Baseline assessments were available in 70 patients (mean age: 70 years; 74.3% male); 19 patients were interviewed at baseline. Additional MCC-specific scores were as follows: Physical Function score (six items), Psychological Impact score (six items), and MCC summary score (12 items). FACT-M original and additional MCC-specific scores both demonstrated acceptable psychometric properties: high reliability (Cronbach's alpha: 0.81-0.96), good convergent validity (correlations above 0.4 observed for 88% of items of the Melanoma surgery scale, 75% of items of the Melanoma scale, and 100% of items of the other FACT-M domains). Some evidence of floor/ceiling effects and poor discriminant ability was found. Higher scores (better HRQoL) on all FACT-M domains were observed in patients with better functioning (assessed by ECOG performance score), supporting clinical validity. Despite the small sample for responsiveness analysis (n = 37), the majority of FACT-M scores showed sensitivity to changes in tumor size at Week 7 with small to moderate effect sizes. MIDs were consistent with previously reported values in the literature for FACT-M domains.

Conclusions: FACT-M is suitable to capture HRQoL in patients with metastatic MCC, thus making it a potential candidate for assessing HRQoL in MCC trials.

Trial registration: This study is a post-hoc analysis conducted on data collected in Part A of the JAVELIN Merkel 200 trial. This trial was registered on 2 June 2014 with ClinicalTrials.gov as NCT02155647 .

Keywords: FACT-M questionnaire; Merkel cell carcinoma; Patient-reported outcomes; Psychometric validation; Quality of life.

Conflict of interest statement

Ethics approval and consent to participate

This study was performed in compliance with the ethical principles arising from the Declaration of Helsinki and all current local regulations. The study protocol was approved by an Independent Ethics Committee or Institutional Review Board prior to the study launch at each site. All patients gave written informed consent.

Consent for publication

Not applicable.

Competing interests

MB and MS are employees of Merck KGaA, Darmstadt, Germany. FF, CDB, PW, and AM are employees of Mapi and paid consultants to Merck KGaA, Darmstadt, Germany. LM is an employee of EMD Serono, Boston, MA, USA. Authors did not receive payment for authorship.

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