Editor’s Choice


Advancing evidence-based nursing practice through explicit theory-testing research: focus on the sixth vital sign, fatigue

Fatigue is such a widespread experience of both ill and otherwise well people that it is becoming known as the sixth vital sign. Indeed, virtually every woman who gives birth experiences some degree of postpartum fatigue, which has the potential to interfere with her and her family members’activities of daily living and the quality of the life of the expanding family. The study by Song et al. (2010) in this issue of JAN contributes substantially to understanding postpartum fatigue. Overall, their findings are generalizable to women worldwide, and the inclusion of satisfaction with Sanjujori–a form of postpartum care provided by non-professional caregivers in Korea–sensitizes us to the cultural context of postpartum fatigue.

Researchers who are interested in postpartum fatigue might want to test Song et al.’s theory in other cultures to determine if concepts specific to those cultures are associated with postpartum fatigue. Researchers who are interested in fatigue experienced by people with diverse health conditions may want to use the Song et al.’s theory as a starting point for development and testing of fatigue theories that are specific to those health conditions. Inasmuch as cancer-related fatigue is arguably as intense as postpartum fatigue and may last much longer due to the prolonged course of cancer treatment, I encourage oncology nurse researchers to follow the theoretical lead provided by Song et al.

Song et al.’s study joins a growing number of other explicit theory-generating and theory-testing studies that collectively represent the evidence needed to advance evidence-based nursing practice (see for example, Tsai et al. 2003, Sheehan et al. 2010). Descriptive theory-generating and theory-testing studies yield descriptive theories, which provide evidence for assessments of people’s health-related experiences. Correlational theory-testing studies yield explanatory theories, which provide evidence for more comprehensive assessments of people’s health-related experiences. Experimental theory-testing studies yield predictive theories, which provide evidence for nursing interventions directed toward improving people’s well-being. Hallmarks of Song et al.’s correlational explanatory theory-testing research are the careful explanation of the relation of each concept of their theory to other concepts and a sophisticated analysis of data using structural equation modelling that accounted for some concepts acting as mediators. Their findings revealed a more parsimonious theory than initially proposed, with some relations between some concepts found to be non-significant.

It is, I believe, important to not leap to recommendations for experimental studies to test predictive theories of nursing interventions on the basis of the findings of correlational studies of explanatory theories. Instead, the logical recommendation stemming from any correlational study designed to test an explanatory theory should be comprehensive patient assessment. Accordingly, Song et al.’s study findings provide the evidence needed for comprehensive assessment of women during the postpartum to determine their level of fatigue and concepts that are associated with fatigue, especially postpartum depression and quality of sleep during the postpartum. Furthermore, inasmuch as Song et al. found that childcare stress, unsatisfactory infant feeding, infant difficulty, satisfaction with Sanjujor and social support were indirectly related to postpartum fatigue, a comprehensive assessment might also include those concepts.

The instruments used by Song et al. to measure the theory concepts encompassed 61 items, which may be considered excessive for use in practice. Therefore, if clinicians find that so many items impose undue respondent burden in everyday practice, shorter forms of the instruments or other measures of the theory concepts could be developed. For example, a comprehensive assessment form could be made up of a one-item numerical rating scale or a visual analogue scale for each theory concept.