Quality of life measurement in women with cervical cancer: implications for Chinese cervical cancer survivors

The purpose of this review was to describe existing validated multidimensional QOL instruments used in cervical cancer survivors, and to reveal implications of QOL measurement for Chinese cervical cancer survivors.

Quality of life is dynamic and changes over time [12]. Traditional models of QOL are a multidimensional construct of health including physical, psychological, social and spiritual well-being [13]. It has been argued that this traditional framework predominantly focuses on the individual-centered paradigm, and ignores contextual factors that influence QOL [14]. The contextual QOL model proposed by Ashing-Giwa [14] includes both the individual and systemic paradigms, and was adopted as the framework for this review.

Within each level of paradigm, there are four major domains and a variety of components. The individual level consists of (1) General Health domain including components of health status and co-morbidity; (2) Medical Factors domain including components of age at diagnosis and cancer characteristics; (3) Health Efficacy domain including components of health practices, utilization, perceived health efficacy and medical adherence; and (4) Psychological Well-being domain including components of emotional distress, cognitive function, and positive psychological feelings [14]. The systemic level consists of (1) Socio-ecological domain including components of socio-economic status, life burden, social support, and role/relationship changes; (2) Cultural domain including components of spirituality, acculturation, and interconnectedness; (3) Demographic domain including components of chronological age; and (4) Healthcare System domain including components of access to health care and satisfaction with the quality of health care [14].

Articles published in English or in Chinese from January 2000 to June 2009 were searched for the review. Terms used for searching included cervical cancer, cervix cancer, survivors, survivorship, quality of life, measurement, assessment, and instruments, which were searched in five computerized databases: CINAHL, Medline, PsycInfo, Scopus, and the Chinese Journal Full-text Database (CJFD). In this review, the term 'cervical cancer survivor' was adapted to mean a person living with cervical cancer immediately after the initial diagnosis [15].

Initially, a total of 296 articles were identified from the literature search of the five databases using the above key words. Duplications of articles and those articles that did not meet the selection criteria were removed. Only 53 articles remained. Twelve of these had used self-designed instruments and did not report reliability and validity. As a result, a total of 41 articles were included. The flowchart of search and selection process was outlined in figure 1.

A checklist was used to select the literature. For inclusion, all of the following criteria had to be fulfilled by the articles: (1) QOL was one of primary outcome measures; (2) women with a diagnosis of cervical cancer constituted the study population; (3) papers were published either in English or in Chinese between January 2000 and June 2009 (at time of search). In terms of exclusion criteria, all qualitative studies, commentaries, editorials, literature reviews, and conference proceedings were excluded from this review. As the concept of QOL is multidimensional (including the physical, psychological, social and spiritual well-being dimensions) [13], studies focusing on a single domain of QOL only were excluded.

The basic characteristics of a good QOL instrument should demonstrate evidence of adequate reliability and validity [10]. The most common types of reliability reported for QOL questionnaires are internal consistency (assessing the homogeneity of the scale) and test-retest reliability (assessing the stability of the scale) [16]; common types of validity reported by researchers include content validity (to what degree all items in a QOL instrument quantitatively represent the actual content area of the study) and construct validity (how well items reflect the latent variable in question), which can be assessed by convergent/divergent validation, known-group/contrasted-group validation and factor analysis approaches [17].

According to DeVellis [18], the acceptable level of internal consistency by Cronbach's alpha should be above 0.7. Fitzpatrick et al. [19] suggested that instruments examining test-retest reliability within 2-14 days and achieving a Pearson's correlation of over 0.7 were considered to be acceptable. If calculated by the Kappa coefficient or ICC (Intra-class Correlation Coefficient), an item total correlation of at least 0.2 is coded as acceptable [20]. In terms of construct validity, a convergent correlation score above 0.4 is coded as an acceptable standard [21]. By factor analysis, DeVellis [18] suggested that the eigenvalues of factors greater than 0.5 were considered to be acceptable. With known-group validity, the scale can differentiate among the groups [18].

After careful review of the characteristics and use of instruments in these studies, the instruments could be classified into four categories: generic instruments, cancer-specific instruments, cancer site-specific instruments, and survivor-specific instruments.

The generic questionnaires were designed to assess general aspects of QOL. This category included 4 instruments: the 36-item short form of the Medical Outcome Study questionnaire (SF-36) [22, 23], the World Health Organization Quality of Life-Brief (WHOQOL-BREF) [24, 25], the Quality of Life Index (QLI) [26], and the European Quality of Life Scale-5 dimensions (EQ-5D) [27]. The cancer-specific instruments were designed to assess the QOL of cancer patients as a whole. This category contained 3 instruments: the Cancer Rehabilitation Evaluation System-Short Form (CARES-SF) [28], the European Organization for Research Treatment's Quality of Life Questionnaire (EORTC QLQ-C30) [29, 30], and the Functional Assessment of Cancer Therapy-General (FACT-G) [31, 32]. The cancer site-specific QOL instruments were developed to measure the QOL of cervical cancer patients. This category consisted of 3 scales: the EORTC Quality of Life Questionnaire-Cervix-24items (QLQ-Cx24) [33], the Functional Assessment of Cancer Therapy-Cervix (FACT-Cx) [34, 35], and the Quality of Life Instruments for Cancer Patients-Cervical Cancer (QLICP-CE) [36]. The survivor-specific category included the Cancer Survivors' Unmet Needs (CaSUN) scale [37], which was developed to assess QOL among long-term cancer survivors using a needs-based approach.

A brief description of each instrument, including categories, origin of countries and sample items, is shown in additional file 1. While these instruments varied in length and emphasis, they shared the common perspective that QOL is a multidimensional concept including physical, psychological, social and spiritual well-being, and environmental conditions.

There was a great variation in the domains and number of items in these 11 multidimensional QOL instruments. While these instruments were developed by different researchers and framed by different QOL models with combinations of related domains, it was considered beneficial to identify the common shared domains and components adopted to assess QOL among cervical cancer survivors. The item distribution of these 11 multidimensional instruments was tabulated according to Ashing-Giwa's contextual QOL model [14] (additional file 2).

Additional file 2 shows that, at the individual level, items in these QOL instruments mainly covered the domains of 'general health' and 'psychological health', with few covering 'medical factors' and 'health efficacy'. At the systemic level, these QOL instruments mainly included items to measure the socio-ecological domain, i.e. in the components of 'socio-economic status', 'social support', and 'role/relationship changes'. Very few items in these instruments covered the 'cultural domain' or the 'healthcare system'.

Additional file 3 also shows the psychometric properties of reliability and validity. The internal consistency of these 11 established multidimensional QOL instruments met the acceptable standards (0.68-0.99). In terms of the test-retest correlation, the average item-item correlation of CaSUN by Kappa coefficient was 0.13, below the acceptable level of correlation. Although the test-retest reliability of QLICP-CE was 0.95 by Pearson's coefficient test, the retest interval was a mere 2-3 days. Chawalow & Adesina [57] indicated that high test-retest correlation indices obtained over a short period (<1 week) may simply be reflected memory rather than actual stability of participants' perceptions. Consequently, higher test-retest correlations do not actually reflect the stability of an instrument if the retest interval is short.

For the establishment of validity, all these instruments had one or more types of construct validity reported. Most had conducted convergent validity which met acceptable standards. Other reported approaches of validity, such as factor analysis and known-group validation, were also considered acceptable.

The original versions of these 11 QOL instruments were mainly developed in Europe and North America, therefore how to select those that would be most appropriate for Chinese cervical cancer survivors requires careful consideration by researchers.

Among the generic scales, the WHOQOL-BREF was the most often-used scale among QOL studies in cervical cancer survivors. Some studies chose this scale because it had been translated and validated in their language [24, 25]. Hence, these studies chose generic scales based on practical issues. One study chose the generic scale of QLI because there was a control group from the general population [26]. Generic scales were designed and validated in the general population. If the study objectives aimed at making a comparison of QOL between cancer survivors and the general population, choosing one of the generic scales would be suitable. However, while these generic instruments may be useful for making comparisons of QOL between cervical cancer survivors and the general population, they may not be sensitive enough to detect the impact of cancer and cancer treatment on QOL among cervical cancer survivors.

The majority of QOL studies in cervical cancer survivors chose cancer-specific scales. EORTC QLQ-C30 and FACT-G were the most frequently used. It is possible that cancer-specific scales are more responsive to changes than their generic counterparts, because cancer-specific instruments cover items in addressing the effects of cancer and related treatment on QOL. In consequence, it would be logical to speculate that cancer-specific scales would be more appropriate than generic scales in assessing QOL among cancer survivors. However, this speculation is only partially substantiated. Due to a failure to identify concerns specific to cervical cancer, these instruments may not be the most suitable for assessing QOL among cervical cancer survivors.

Cancer site-specific instruments may achieve greater specificity and sensitivity than either generic or cancer-specific scales, as site-specific scales cover general cancer-specific issues and address specific concerns related to cervical cancer. There were three site-specific instruments used by studies in our review: EORTC QLQ-Cx24, FACT-Cx and QLICP-CE. It may be speculated that these cancer site-specific scales are the most suitable choice for QOL studies in cervical cancer survivors. Yet these scales are more concerned with the immediate effects of cancer and acute cancer treatment, so that they are not appropriate for cervical cancer survivors due to the lack of items covering the long-term sequelae of cervical cancer, such as loss of fertility, sexual dysfunction, fear of recurrence, and body image disturbance [58].

In addition, cancer survivors reported positive changes in life outlook, self-growth, precious life, and an appreciation of their relationships with others [37]. All 11 QOL instruments used in cervical cancer survivors paid less attention to the positive outcome of the cancer survivorship experience. In more recent years, the trend of QOL instrument production has continued to emerge for cancer survivors, particularly for long-term (more than 5 years) cancer survivors with an emphasis on positive outcomes [10], such as the Quality of Life Scale for Adult Cancer Survivors (QLACS) by Avis et al. [59] and the Impact of Cancer (IOC) by Zebrack et al. [60]. However, these long-term cancer survivor-specific instruments have not been applied to the population of cervical cancer survivors.

According to Ashing-Giwa's contextual model [14], socio-ecological, cultural and healthcare system-related factors are essential components in the systemic level of QOL among cancer survivors. Additional file 2 shows the paradigm, domains, components and item distribution. These 11 multidimensional QOL instruments did not adequately incorporate the contextual milieu. In other words, there were few items that captured the contextual domain of QOL, such as socio-ecological and cultural issues. Even if the instrument of WHOQOL-BREF had an environmental domain, this scale covered too few items to measure the environmental domain of QOL adequately. Therefore, neither of these instruments was comprehensive enough to address or cover all QOL issues among cervical cancer survivors.

Although the instruments of EORTC QLQ-C30, FACT-G, and FACT-Cx had been applied to Chinese cervical cancer survivors, few studies calculated its reliability and validity when applied to Chinese women. Only one study by Wan et al. [61] established and reported FACT-G as having good reliability and validity among different types of Chinese cancer patients.

Recently, Zhang and colleagues developed the scale of QLICP-CE and validated it among a group of Chinese women with cervical cancer [36]. The domains and items included in the scale of QLICP-CE were mainly based on the instruments of EORTC QLQ-C30 and FACT-Cx. The QLICP-CE emphasized the aspects of women's appetite and sleep, as within Chinese culture good appetite, sleep and energy are highly regarded in daily life [62]. Due to Chinese communities viewing sex as a taboo topic, the QLICP-CE consists of just one item to measure the issues of sexual health. As sexuality is one of the essential components of QOL [63], this scale failed to address an important aspect of QOL for Chinese cervical cancer survivors.

Furthermore, culture is a major determinant of QOL, as perceptions of QOL are embedded in cultural beliefs about what constitutes normality and health [64]. At the individual level, the components of health practices, health utilization and perceived health practice should be measured in a culturally sensitive manner, because in Chinese culture the beliefs of Taoism (human beings should live in harmony with nature, that is, with 'Tao' as the way of life) and traditional Chinese medicine (TCM) (expanded from Taoism, it views health as harmony between vital energy - known as Qi - within and between the body and its environment) are dominate the views of health and health utilization [62, 65]. These beliefs are different from those of Western people, therefore perceptions of QOL logically also differ between China and the West. Due to differences of social backgrounds and healthcare systems, at the systemic level the components of socio-economic status, access to and satisfaction with health care, and role and relationship changes should be particularly emphasized. Since the family relationship and kinship play very important roles in daily life in Chinese communities [62], roles and relationship changes due to cancer and treatment greatly influence Chinese women's QOL.

In searching for literature, the 5 electronic databases used provided a comprehensive coverage of key English and Chinese medical, nursing and health-affiliated journals. However, the titles and abstracts were screened only by the first author. In order to compensate for this limitation, all articles were screened using a checklist based on clear inclusion and exclusion criteria. Additionally, all eligible articles were agreed upon by the research team. Other limitations include that the assessment of the psychometric properties of QOL instruments was limited to the reliability and validity. This review failed to assess other instrument properties, such as cross-cultural acceptability, responsiveness, and acceptability, because those properties were seldom reported by the instrument developers.