title: Satisfaction with Life Scale (SLS-6): First validation study in Parkinson's disease population.
abstract: BACKGROUND
  To explore the psychometric attributes of a new Satisfaction with Life Scale (SLS-6) in a wide Spanish-speaking population with Parkinson's disease (PD).
  
  
  METHODS
  This was an international, cross-sectional study. Several rater-based and patient-reported outcomes measures for evaluation of PD (e.g., Scales for Outcomes in Parkinson's Disease-Motor) and other constructs (e.g., Duke-UNC Functional Social Support Questionnaire, Scale for Living with Chronic Illness) were applied together with the SLS-6. Acceptability, scaling assumptions, reliability, precision, and construct validity were tested.
  
  
  RESULTS
  The study included 324 patients from five countries, with age (mean ± standard deviation) 66.67 ± 10.68 years. None of the SLS-6 items had missing values and all acceptability parameters fulfilled the standard criteria. Scaling assumptions allowed the calculation of a summary index from items 2 to 6, complementary to the global evaluation (item 1). For these five items, Cronbach's alpha was 0.85; the corrected item-total correlation 0.53-0.73; inter-item correlation, 0.45-0.70, with an item homogeneity index of 0.55. The standard error of measurement, based on Cronbach's alpha for a single observation, was 3.48. SLS-6 correlations were moderate to strong (rs ≥ 0.35) with the patient-reported outcomes and weak to moderate with the rater-based assessments used in the study. The SLS-6 total score was significantly different according to PD severity levels established according to Hoehn and Yahr staging, Clinical Impression of Severity Index, and Patient-Based Global Impression of Severity scale.
  
  
  CONCLUSIONS
  The results suggest that SLS-6 is an easy, feasible, acceptable, consistent, precise and valid measure to evaluate satisfaction with life in PD patients.
authors.affiliation: Faculty of Nursing, University of Navarre, C/ Irunlarrea, s/n, Edificio de los Castaños, 31008 Pamplona, Navarre, Spain.
authors.forename: Leire
authors.initials: L
authors.lastname: Ambrosio
authors.affiliation: Faculty of Health Sciences, University of Southampton, Building 67, Highfield Campus University Road, S0171BJ, Southampton, UK.
authors.forename: Mari Carmen
authors.initials: MC
authors.lastname: Portillo
authors.affiliation: National Centre of Epidemiology and CIBERNED, Carlos III Institute of Health, Av. Monforte de Lemos, 5, 28029 Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Rodriguez-Blazquez
authors.affiliation: Neurology Unit, Ramon y Cajal University Hospital, IRYCIS. Ctra. de Colmenar Viejo, 28034 Madrid, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Martínez-Castrillo
authors.affiliation: National Institute of Neurology and Neurosurgery, Movement Disorders Clinic, Insurgentes Sur 3877, Colonia La Fama, 14269 Mexico City, DF, Mexico.
authors.forename: Mayela
authors.initials: M
authors.lastname: Rodriguez-Violante
authors.affiliation: Movement Disorder and Biostatistics Units, Neurological Service, Carlos Andrade Marín Hospital, Ayacucho s/n y Av. 18 de Septiembre, 170402 Quito, Ecuador.
authors.forename: Marcos
authors.initials: M
authors.lastname: Serrano-Dueñas
authors.affiliation: Neuroscience Area, Vithas-Xanit International Hospital, Avenida de los Argonautas s/n, 29630 Benalmádena, Malaga, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Campos-Arillo
authors.affiliation: Department of Neurology, JM Ramos Mejia Hospital, Urquiza 609, 1221 Buenos Aires, Argentina.
authors.forename: Nelida Susana
authors.initials: NS
authors.lastname: Garretto
authors.affiliation: Department of Neurology, JM Ramos Mejia Hospital, Urquiza 609, 1221 Buenos Aires, Argentina.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Arakaki
authors.affiliation: Department of Movement Disorders and Neurodegeneration, CIREN. Ave 25 # 15805, 11300 Cubanacán, Playa, La Habana, Cuba.
authors.forename: Mario
authors.initials: M
authors.lastname: Álvarez
authors.affiliation: Department of Movement Disorders and Neurodegeneration, CIREN. Ave 25 # 15805, 11300 Cubanacán, Playa, La Habana, Cuba.
authors.forename: Ivonne
authors.initials: I
authors.lastname: Pedroso-Ibáñez
authors.affiliation: Faculty of Nursing, University of Navarre, C/ Irunlarrea, s/n, Edificio de los Castaños, 31008 Pamplona, Navarre, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Carvajal
authors.affiliation: Faculty of Health Sciences, University of Southampton, Building 67, Highfield Campus University Road, S0171BJ, Southampton, UK. Electronic address: pmartinez@isciii.es.
authors.forename: Pablo
authors.initials: P
authors.lastname: Martinez-Martin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000523:psychology*; D010549:Personal Satisfaction; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life
keywords: Parkinson's disease; SLS-6; Satisfaction with Life Scale; Self-assessment; Validation