Original ArticleAge, sex, and comorbidities were considered in comparing reference data for health-related quality of life in the general and cancer populations
Introduction
Because mortality and complications associated with cancer surgery are decreasing and the number of survivors is increasing [1], [2], [3], more concern is being directed to treatment-related sequelae and their effects on health-related quality of life (HRQOL) [2], [3], [4], [5]. HRQOL data can help physicians evaluate the effect of treatment on patients' lives in ways the patients might not be able to communicate themselves [6]. Recently, the use of HRQOL self-administered questionnaires has become a standard tool for the evaluation of new therapies [5], [6], [7], [8], [9], [10] and is steadily gaining importance in clinical decision-making [11], [12], [13]. These questionnaires include the European Organization for Research and Treatment of Cancer (EORTC) Quality-of-Life Questionnaire Core 30 (QLQ-C30) [14] and the Functional Assessment of Cancer Therapy scale (FACT) [15]. Because of the under-recognition of mental disorders, a screening test such as Hospital Anxiety and Depression Scale (HADS) is recommended as part of routine cancer patient care [16], [17]. Additionally, the McGill Quality-of-Life (MQOL) assessment tool can be used to evaluate existential well-being, especially for patients under palliative care [18].
Some questionnaires have been tested in the general population, and reference databases are now available for the EORTC QLQ-C30 [8], [9], [12], [13], FACT-G (for General) [10], [11], and HADS [19], [20]. Direct quality-of-life (QOL) comparisons for different treatment regimens together with population-based reference data have provided more detailed insights into the QOL of cancer patients [7], [9], [11], [13], [21], [22]. Population-based data can also be used to identify subgroups at increased risk of poor HRQOL and affective disorders, and to develop ways to facilitate rehabilitation [9], [12], [23], [24]. Additionally, the data can be used to evaluate the impact of age, sex, and comorbidities on HRQOL in the general population for comparison with cancer patients.
A meta-analysis of Western data, however, indicated that QOL values differed between countries, and that may be true in Asia also. It is possible that differing cultural ideas about QOL could explain the differences. Although the EORTC QLQ-C30 and FACT-G questionnaires have developed site-specific modules for lung [25], stomach [26], and breast cancer [27], we have no population-based reference data to weigh them against. Additionally, considering the many studies that focus on existential well-being, especially for patients under palliative care, reference values would increase the utility of MQOL.
Consequently, we decided to perform a study with the several HRQOL questionnaires in a random sample from the general Korean population representative on age and sex. Our aims were (1) to provide general Korean population reference data for the EORTC QLQ-C30, LC13, STO22, and BR23, HADS, and MQOL, (2) to evaluate the impact of age, sex, and number of comorbidities on the self-rated HRQOL in the general population, and (3) to compare the available population-based EORTC QLQ-C30 and HADS data from different countries.
Section snippets
Study design and subject recruitment
Our goal was to survey 1,000 members of the general population distributed over 15 sites. At each site, the survey was conducted in two strata (age and sex), according to the guidelines of the 2000 Census of Korea. Thus, each sex was represented equally. We selected villages and streets for final sample selection using a probability-proportional-to-size (PPS) technique, which is widely used and is the recommended method for obtaining a representative national sample [28]. It is most useful when
Subjects and recruitment results
Of 2,483 eligible persons ≥20 years old, 1,483 refused to participate or did not complete the survey; 1,000 did complete informed consent; and the survey, yielding a response rate of 40.3%. The most frequent reasons people gave for refusing to participate were that they felt too busy to complete the questionnaire (n = 670), that the survey was inconvenient (n = 332), that they did not want to provide personal information (n = 165), or others. The 500 men who responded had a mean age of 41.1 years
Discussion
This study is the first to present scores from a general Asian population sample on the various dimensions of HRQOL assessed by the EORTC QLQ-C30 and HADS. It is also the first to present EORTC QLQ-LC13, STO22, and BR23 and MQOL general population data that can be used for clinical comparisons.
The tendency for women to have lower HRQOL scores and a higher proportion of health problems is in agreement with earlier self-rated health studies [14], [15]. Our findings are also in agreement with the
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