Original article
Comprehensive assessment of peri-operative fatigue: development of the Identity-Consequence Fatigue Scale

https://doi.org/10.1016/j.jpsychores.2005.08.008Get rights and content

Abstract

Objective

Fatigue is one of the complaints most widely reported during peri-operative periods. However, despite its prevalence, the aetiology of this fatigue remains poorly understood. Recent meta-analysis suggests that the limited applicability of existing fatigue measures is contributing to the current lack of understanding. This research therefore sought to use a rigorous analytic process to develop a comprehensive measure of fatigue suitable for use with recovering surgical patients.

Methods

Content analysis was undertaken to investigate the structure of 55 items initially generated. Self-report questionnaires were then distributed to surgical out-patients, and the 177 responses analysed using principal components analysis. Once item selection was finalized, the convergent and discriminant validity of the new measure was assessed.

Results

The new measure, the Identity-Consequence Fatigue Scale (ICFS), has 28 items and five subscales. All subscales show high internal reliability, and reentry of deleted items showed that the finalized items form a robust component structure. Discriminant validity analysis confirmed that all ICFS subscales are distinctive from depression and anxiety. Convergent validity analysis confirmed the extent to which the ICFS assesses Fatigue-Consequences is a unique feature of the new measure.

Conclusion

The ICFS has a clear and stable structure that offers more comprehensive assessment of fatigue than provided by the measures most widely used in postsurgical fatigue (PSF) literature to date.

Introduction

Fatigue is one of the complaints most widely reported during peri-operative periods. For example, postsurgical fatigue (PSF) has been identified as the principal subjective problem facing many patients following otherwise uncomplicated surgery [1]. Fatigue has been shown to continue resolving for as long as 3 months following major gastrointestinal surgery [2] and ranks as prominently as pain when patients identify factors delaying return to work [3].

Despite the prevalence and impact of fatigue following surgery, the aetiology of PSF remains poorly understood. Rubin and Hotopf [1] identify use of small sample sizes and incomplete reporting of methods and results as factors perpetuating this situation “…but more worrying still was the poor quality of the questionnaires used to assess postoperative fatigue” (p. 980).

Christensen's visual analogue scale (VAS) of fatigue and the fatigue-inertia and vigor-activity subscales of the Profile of Mood States (POMS) are the measures most widely used in PSF studies. Christensen's VAS is a single-item measure assessing fatigue on a scale of 1 to 10. Smets et al. [4] and Schwartz et al. [5] caution against use of single-item measures as they consider that such scales preclude comprehensive description of patient fatigue experiences. For example, single-item measures do not allow differential description of mental and behavioural aspects of fatigue.

While the fatigue and vigor subscales of the POMS contain more than single items, the scope of these scales is still too narrow for research relating to PSF. The POMS was designed specifically to assess mood [6]. In line with this, the fatigue and vigor subscales are adjective lists relating to feelings of tiredness and vigor. However, fatigue is widely considered more than solely a mood state. Examples of broader conceptualizations are found in the large number of measures that address both physical and mental dimensions of fatigue (e.g., the Chalder Fatigue Scale [7]) and the smaller number of measures that include functional/behavioural items (e.g., the Checklist of Individual Strength [8]). Thus, review of both Christensen's VAS and the POMS highlights inadequacies in the way fatigue is being conceptualized within PSF research.

Recent developments in illness perception theory and research provide an alternative framework with which to conceptualize conditions like fatigue. Leventhal's common-sense model of illness self-regulation is a leading theoretical framework within illness perception research, and Contrada et al. [9] suggest that this model provides an appropriate framework in which to understand and explore individual's reactions to surgery. The model suggests that in order to make sense of and respond to health threats, patients create their own models or representations of the health challenges they experience [10]. Across diverse conditions, cognitive aspects of these representations have been identified as being organized into five dimensions (for review, see Ref. [11]). The five components have been labeled identity (symptoms), consequences, cause, timeline and control [10]. Identity relates to patients' ideas about the nature of their condition and focuses on reports of symptoms. Consequence relates to patients' ideas about the impacts their condition has on physical, social and psychological functioning. Cause is personal ideas about aetiology. Timeline is the perceived duration of their condition, and the control component relates to patients' ideas about how one controls or recovers from the condition.

Assessment of these cognitive representations has been used to predict outcomes following a variety of health-related experiences. For example, assessment of cognitive representations has been used to predict rehabilitation attendance following acute myocardial infarction [12], adjustment during episodes of chronic fatigue syndrome [13], and recovery from oral surgery [14]. However, the cognitive representation framework has yet to be applied to examination of outcomes following major surgery.

In terms of applying Leventhal's framework of cognitive representation to PSF research, measures such as the IPQ-R [15] can provide suitable assessment of patient beliefs relating to timeline, cause and control; what appears to be lacking from existing literature is a measure that comprehensively assesses the Identity and Consequences of PSF. In order to remedy this, our study sought to identify the most appropriate fatigue and vigor items for assessing the energy levels of surgical patients and to identify items suitable for assessing both the mental and behavioural consequences of PSF.

To develop the Identity-Consequence Fatigue Scale (ICFS), an initial item pool was generated using patient interviews and existing measures. Content analysis was undertaken to explore the conceptual structure of these items. Those items retained following content analysis formed an anonymous questionnaire which was distributed to surgical out-patients. Principal components analysis was used to analyse responses to this questionnaire. Results from the component analysis, coupled with information from reliability analysis, guided item selection for the ICFS. Following finalization of the ICFS items, principal components analysis was undertaken to assess the extent of discrimination between ICFS scores and scores on widely used measures of anxiety and depression. Finally, convergent validity analysis was undertaken to examine the relationship between the ICFS and the measures most widely used in existing PSF research. The details of each of these stages are presented below. Overall, the process has developed a new and more comprehensive measure of fatigue.

Section snippets

Item development

Review of existing fatigue questionnaires and illness representation measures was used to develop an initial item pool representing the dimensions Fatigue-Identity (sensations) and Fatigue-Consequences. Within these two dimensions, 55 items were conceived as representing seven subscales. These subscales were labeled feelings of fatigue, feelings of vigor, bodily sensations of fatigue, mental, impacts on motivation, impacts on general energy levels and impacts on activities of daily living (see

Results

The dimensional distinctions of Identity and Consequence were largely maintained during the content analysis. However, the mental fatigue subscale was an exception to this pattern. Four of the five participants considered that the items of the mental fatigue subscale were best conceptualised as a consequence of fatigue. Thus, items belonging to mental fatigue subscale were moved to the Fatigue-Consequences dimension and the new subscale labeled impacts on concentration.

In addition, within each

Items

A questionnaire was developed using the 48 items that remained following the content analysis. All items were rated on six-point adjectival scales with anchors from “not at all” to “all of the time” or “not at all” to “more often than usual.” In making their responses, participants were asked to think over how they had felt during the last 3 days.

Participants

From 365 questionnaires distributed to patients, 177 useable responses were received. Most participants were surgical out-patients at Middlemore

Data preparation

During component analyses, departures from normality, homoscedasticity and linearity are considered only to diminish the correlations observed and therefore do not put the analysis at risk of overestimating the relations among variables [16], [17], [18]. Thus, although some departures from normality were identified in the current data set, transformations were not performed. Two items were removed because they showed 4% missing data; all remaining items showed less than 3.4% missing data.

Assessing the matrices

To be

Participants

Eighty-three of the participants from the component analysis phase also provided data for validity analyses. Table 1 shows demographic characteristics for the validity analysis sample did not differ from the characteristics of the principal component sample.

Procedure

Prior to analysis, all negatively phrased items were reversed, and assumptions of normality and linearity assessed and found to be satisfactory. Discriminant validity was assessed by running a series of confirmatory factor analyses using the

Results

Discriminant validity analysis showed all subscales of the ICFS load as components distinctive from depression and anxiety. For each subscale, ICFS items loaded together and showed the strongest loadings on their component, with feelings of fatigue items loading between .58 and .89, feelings of vigor items −.71 to .83, impacts on concentration .53 to .80, impacts on energy items .64 to .82 and impacts on daily activity items .56 to .83. Throughout these analyses, no secondary loadings above .50

Discussion

In their recent meta-analysis, Rubin and Hotopf [1] raise concerns regarding the poor quality of questionnaires previously used to assess postoperative fatigue. The research reported herein addresses these concerns by using a theoretically informed conceptualization and a rigorous analytic process to develop a new measure of fatigue.

This new measure, the ICFS, was developed to assess fatigue more comprehensively than the measures most widely used in existing PSF research. Patients' descriptions

References (25)

  • MS Hagger et al.

    A meta-analytic review of the common-sense model of illness representations

    Psychol Health

    (2003)
  • KJ Petrie et al.

    Role of patients' view of their illness in predicting return to work and functioning after myocardial infarction: longitudinal study

    Br Med J

    (1996)
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