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  • Exploring the consistency of the SF-6D
    Publication . Ferreira, Lara Noronha; Ferreira, Pedro L.; Pereira, Luis; Rowen, Donna; Brazier, John E.
    Objective: The six dimensional health state short form (SF-6D) was designed to be derived from the short-form 36 health survey (SF-36). The purpose of this research was to compare the SF-6D index values generated from the SF 36 (SF-6D(SF-36)) with those obtained from the SF-6D administered as an independent instrument (SF-6D(Ind)). The goal was to assess the consistency of respondents answers to these two methods of deriving the SF-6D. Methods: Data were obtained from a sample of the Portuguese population (n = 414). Agreement between the instruments was assessed on the basis of a descriptive system and their indexes. The analysis of the descriptive system was performed by using a global consistency index and an identically classified index. Agreement was also explored by using correlation coefficients. Parametric tests were used to identify differences between the indexes. Regression models were estimated to understand the relationship between them. Results: The SF-6D(Ind) generates higher values than does the SF-6D(SF-36), There were significant differences between the indexes across sociodemographic groups. There was a significant ceiling effect in the SF-6D(Ind) a but not in the SF-6D(SF-36). The correlation between the indexes was high but less than what was anticipated. The global consistency index identified the dimensions with larger differences. Considerable differences were found in two dimensions, possibly as a result of different item contexts. Further research is needed to fully understand the role of the different layouts and the length of the questionnaires in the respondents' answers. Conclusions: The results show that as the SF-6D was designed to derive utilities from the SF-36 it should be used in this way and not as an independent instrument.
  • Comparing the performance of the EQ-5D-3L and the EQ-5D-5L in young Portuguese adults
    Publication . Ferreira, Lara Noronha; Ferreira, Pedro L.; Perdigão, Filipa; Pereira, Luis
    Background Some studies have reported a ceiling effect in EQ-5D-3L, especially in healthy and/or young individuals. Recently, two further levels have been included in its measurement model (EQ-5D-5L). The purposes of this study were (1) to assess the properties of the EQ-5D-5L in comparison with the standard EQ-5D-3L in a sample of young adults, (2) to foreground the importance of collecting qualitative data to confirm, validate or refine the EQ-5D questionnaire items and (3) to raise questions pertaining to the wording in these questionnaire items. Methods The data used came from a sample of respondents aged 30 or under (n = 624). They completed both versions of the EQ-5D, which were compared in terms of feasibility, level of inconsistency and ceiling effect. Agreement between the instruments was assessed using correlation coefficients and Bland-Altman plots. Known-groups validity of the EQ-5D-5L was also assessed using non-parametric tests. The discriminative properties were compared using receiver operating characteristic curves. Finally, four interviews were conducted for retrospective reports to elicit respondents’ understanding and perceptions of the format, instructions, items, and responses. Results Quantitative results show a ceiling effect reduction of 25.3 % and a high level agreement between both indices. Known-groups validity was confirmed for the EQ-5D-5L. Explorative interviews indicated ambiguity and low degree of certainty in regards to conceptualizing differences between levels moderate-slight across three dimensions. Conclusions The EQ-5D-5L performed better than the EQ-5D-3L. However, the explorative interviews demonstrated several limitations in the EQ-5D questionnaire wording and high context-dependent answers point to lack of illnesses’ experience amongst young adults.
  • Erratum to: Reducing the floor effect in the SF-6D: a feasibility study (vol 7, pg 193, 2012)
    Publication . Ferreira, Lara Noronha; Ferreira, Pedro L.; Pereira, Luis; Rowen, Donna
    Erratum to: Reducing the Floor Effect in the SF-6D: A Feasibility Study
  • Sondagens a turistas: como medir o erro amostral?
    Publication . Pereira, Luis; Ferreira, Lara N
    Na maioria das sondagens realizadas na área do turismo não tem existido preocupação na mediação do erro amostral das estimativas produzidas para os parâmetros de interesse. Desta forma, uma vez realizada uma sondagem a turistas e publicados os seus resultados, desconhece-se geralmente quão próximas se encontram estas estimativas dos respectivos verdadeiros valores dos parâmetros populacionais desconhecidos. Este artigo pretende fazer uma revisão das principais metodologias existentes para medir o erro amostral em sondagens a turistas.
  • Assessing quality of life of self-reported rheumatic patients
    Publication . Ferreira, Pedro L.; Gonçalves, Sónia P.; Ferreira, Lara Noronha; Pereira, Luis; Antunes, Patrícia; Gouveia, Nélia; Rodrigues, Ana; Canhão, Helena; Branco, Jaime
    were used to identify factors associated with HRQoL. Respondents with self-reported RD assigned a lower self-perception to their health status. The burden of disease was observed mainly in physical function, role physical and bodily pain. The EQ-5D-3L dimensions show similar results: the intensity of problems is significantly more evident in respondents with self-reported RD. HRQoL of respondents with self-reported RD is related to sociodemographic variables and is significantly lower when compared with the Portuguese population. Four clusters of homogeneous respondents with self-reported RD were formed and characterized according to a number of variables. Factors associated with HRQoL were identified. In conclusion, suffering from a self-reported RD has a significant impact on self-perceived health status and on the quality of life. The aims of this study were to assess the health-related quality of life (HRQoL) in patients with self-reported rheumatic diseases (RD), to classify self-reported rheumatic patients in groups according to their health state and to explore the associations between health status and sociodemographic variables. Data came from the Portuguese Epidemiologic study of the RD. A sample of the Portuguese population aged 18 or more (n = 10,661) stratified by region and locality dimension was interviewed by trained interviewers and answered a standardized questionnaire that included the SF-36v1, the EQ-5D-3L, medical history, identification of potential rheumatic diseases, sociodemographic characteristics, among others. Descriptive statistics and parametric tests were used to compare HRQoL of respondents with and without RD. Comparisons with normative data from the Portuguese population were also carried out. A cluster analysis was used to classify respondents into homogeneous groups. Regression analyses were used to identify factors associated with HRQoL. Respondents with self-reported RD assigned a lower self-perception to their health status. The burden of disease was observed mainly in physical function, role physical and bodily pain. The EQ-5D-3L dimensions show similar results: the intensity of problems is significantly more evident in respondents with self-reported RD. HRQoL of respondents with self-reported RD is related to sociodemographic variables and is significantly lower when compared with the Portuguese population. Four clusters of homogeneous respondents with self-reported RD were formed and characterized according to a number of variables. Factors associated with HRQoL were identified. In conclusion, suffering from a self-reported RD has a significant impact on self-perceived health status and on the quality of life.
  • EQ-5D-5L valuation study for Portugal
    Publication . Ferreira, Pedro L.; Antunes, Patricia; Ferreira, Lara; Pereira, Luis
    Although the EQ-5D-3L still is the most popular preferencebased instrument worldwide, we anticipate that the new version EQ5D-5L with five levels within each dimension will be more used and is likely to leave behind the previous one.