The 18-item Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF, Scherber et al Blood 2011) given in conjunction with the 9-item Brief Fatigue Inventory (BFI, Mendoza et al Cancer 1999) is a patient-completed questionnaire for assessing symptoms in persons with MPNs. The MPN-SAF has been translated and validated in 9 languages to date. The Total Symptom Score (TSS) is computed from 10 of the most pertinent MPN-SAF items to assess symptom burden in MPN patients and to evaluate response to therapy. Psychometric properties of the TSS have been previously reported (Emanuel et al Blood 2012). The purpose of this analysis is to compare MPN-SAF symptoms and psychometric properties of the TSS across 9 languages in an international sample.
Data were collected in an international cohort of subjects with MPNs. Surveyed symptoms included fatigue, early satiety, abdominal pain and discomfort, inactivity, headaches, concentration, dizziness, extremity tingling, insomnia, sexual problems, mood changes, cough, night sweats, pruritus, bone pain and fever on a 0 (absent) to 10 (worst imaginable) scale. TSS was computed using the published scoring algorithm on a 0 (all symptoms absent) to 100 (all symptoms worst imaginable) scale. Demographic and disease-related data including disease type, gender, and age had to be present to be included in analysis. Demographics were compared across languages groups using ANOVA and chi-squared tests. Symptoms and TSS were compared across language groups using a general linear model adjusting for disease type, age, and gender with post-hoc Tukey pairwise comparisons. Internal consistency and factor structure of the TSS were investigated overall and within language groups using Cronbach's alpha and principal-axis factoring analysis.
1,851 subjects with polycythemia vera (PV N=655), essential thrombocythemia (ET N=769) and myelofibrosis (MF N=427; 286 primary MF, 61 PV-MF, 80 ET-MF) were prospectively enrolled and administered the MPN-SAF and BFI in 1 of 9 languages: English [UK] 55, English [US] 102, Italian 186, Swedish 114, German 112, French 457, Spanish 192, Dutch 236, and Chinese 397. Age (median 61, range, 15–94) and gender (55% F) were typical. Disease type and age varied across language groups (both p <0.001).
Symptom frequencies ranged from 19% (fever) to 88% (fatigue) overall with mean severities ranging from 0.4 (SD=1.3, fever) to 4.3 (SD=2.3, fatigue). Fatigue had the highest mean severity among all symptoms within each language group. Overall, mean TSS was 21.5 (SD=16.7) with the Swedish (mean=18.1, SD=15.2) and Dutch (mean=27.6, SD=17.1) cohorts reporting the lowest and highest unadjusted TSS means, respectively. When comparing symptom items across languages (adjusting for disease type, age, and gender), concentration and sexual problems had the most statistically significant pairwise differences (11 and 10, respectively, out of a possible 36) followed by dizziness and overall quality of life (9 each, out of a possible 36). No statistically significant pairwise differences were observed for abdominal discomfort, headache, extremity tingling, or insomnia. For the TSS, the Dutch cohort appeared to statistically significantly differ (all p <0.05) with all other languages except the English cohorts. All other TSS pairwise comparisons were not statistically significant.
The TSS had excellent internal consistency overall (Cronbach's alpha 0.83) as well as within language groups (Cronbach's alpha 0.81–0.86). Overall factor analysis identified a single underlying construct among the 10 TSS items. Factor loadings ranged from 0.41 for fever to 0.73 for inactivity. A single factor solution was appropriate for each language group with factor loadings ranging from 0.18 to 0.85.
This analysis suggests that the available translations of the MPN-SAF are generally acceptable for use in a broad context. The TSS demonstrated acceptable internal consistency and similar factor structure across all language groups. Most symptom and TSS comparisons between languages were not statistically significant, but for the few which differed, further studies are needed to evaluate whether these variances are due to disease-related factors or due to linguistic or cultural influences present in the cohorts.
Kiladjian:Novartis: Honoraria, Research Funding; Celgene: Research Funding; Shire: Honoraria. Griesshammer:Shire: Honoraria. Roy:Novartis, BMS: Speakers Bureau. Harrison:Novartis: Honoraria, Research Funding, Speakers Bureau; YM Bioscience: Consultancy, Honoraria; Sanofi Aventis: Honoraria; Shire: Honoraria, Research Funding. Passamonti:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Mesa:Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding.
Asterisk with author names denotes non-ASH members.