Abstract

Objective: Providing an overall view on the importance of the population of informal caregivers and cancer informal caregivers, and a clear conceptual definition of the concept based on in-depth interviews and literature review. Proposing a solid scientific roadmap for scales validation, based on mistakes or approximations noticed in the literature on CQOLC scale in different countries. Design: The American original CQOLC scale was translated and supposedly validated in a number of other countries worldwide. All studies show different dimensionality structures and results, but they also follow different statistical processes: we analyze those. Setting: Literature review to show the magnitude of cancer informal caregiving as public health issues, worldwide as far as information is available. Proposition of a more comprehensive definition, based on 35 pilot interviews conducted in a Spanish hospital. A comparison of 9 studies (including the original American scale) allows a careful analysis of the followed process (scale items selection, translation, sample recruitment, statistic process). us to point out weaknesses or mistakes in the scale validation processes. Results: Most of the 9 scales, including the original one, suffer from severe limitations in the subjects recruitment procedures (too few cancer types often from 1 to 3), (very) limited types of caregivers in term of relationship with the patient, removing caregivers who have had a cancer, or with low education level, etc.). Several scales see items removed even before any statistical analysis be performed, because the authors believe that they are not adapted to the population. This impoverishes the scale content and its ability to capture all facets of the concept of QOL. Finally, the factorization leads to removing too many items under the criteria of removing items which are single or which load on two factors; removal reach sometimes till 30% of the scale, impoverishing the scale even more. There are strong discrepancies across studies in how they use statistical criteria for purifying the scale (ex. Kaiser, scree, Cattell tests); too few tests are used except in one study; and in many cases purification is too strict as mentioned here above. Conclusion: There is no consensus, or maybe even not enough knowledge, of how and why, under which criteria, should the author perform the following actions: a) Removing items from the original scale b) Recruiting subjects (here caregivers) in a manner which fully represent the studied population under several important characteristics c) Conducting a clean and scientifically justified scale factorization, and if necessary, purification process. d) As a conclusion, we cannot know if the scales dimensionality variations are due to the commented methodological differences, or to true populations’ differences. 

Keywords

Methodology, scale validation, quality of life, cancer informal caregivers, cross cultural comparison.