The test–retest reliability of the mean of overall FDQ score was intraclass correlation (2,1) 0.918 and SEM 5.9 points of a possible total score of 130 on the FDQ. This indicates excellent reliability.21 The Bland–Altman plot revealed that there was little difference between tests. Specifically, all the plot's points fell within 1.96 SD of the mean FDQ scores, except for 1; refer to Figure 4.
Minimal Detectable Change
The MDC for the FDQ score was 16.35 of 130 (in cm), which represents the threshold to detect change beyond that of random error.
This study investigated the development of a new questionnaire, the FDQ, which is specific to the thoracic cage and assesses functional outcomes after cardiac surgery. Our findings demonstrate that the FDQ is an appropriate tool for this purpose, and that those undergoing cardiac surgery procedures can safely and effectively complete it preoperatively and postoperatively. The FDQ is adaptable in nature, making it particularly suitable in the acute postoperative phase. Each of the component tasks is based on tasks that are completed on a daily basis, and so if individuals are unable to complete the task at the time of assessment (e.g. secondary to fatigue), they can base their response on the last time they completed it.
The FDQ was developed as literature has highlighted that people experience difficulties with functional tasks that challenge the thoracic cage and upper limbs after cardiac surgery. Its content was devised based on these scientific publications1,4,22 and clinical practice within this population. It was also informed by kinematics of the thoracic region, resulting in the identification of 13 items for inclusion within the tool. This study demonstrated that the FDQ has good internal consistency,23 with a Cronbach alpha coefficient of 0.971. If component tasks were deleted from the questionnaire, Cronbach alpha values were assessed, but no single item yielded a value greater than 0.971, thus indicating that each item of the questionnaire related to every other item and to the instrument as a whole.21
The FDQ displayed moderate to good correlations with measures of pain and HRQOL. After operation, before hospital discharge assessment, there were moderate to good correlations between SF36 vitality and mental health domains, in addition to shoulder pain, sternal pain, and total pain. All other aspects of HRQOL and pain variables displayed a fair relationship. The strongest correlations at this time point were found between the FDQ and sternal pain and total pain scores (r = 0.60, r = 0.69 respectively). Arguably, sternal pain and total pain are 2 of the most significant symptoms after cardiac surgery. Both display proportionally larger changes in scores across time after cardiac surgery compared with other assessments. Furthermore, thoracic mobilization exercises have been shown to significantly decrease sternal pain at the 4-week postdischarge review.16
Correlations with HRQOL early after operation were stronger with vitality, mental health, and role emotion domains compared with the physical SF36 domains of role physical and physical function. This may be accounted for by the more general nature of the SF36 physical components, which may be less relevant in the early postoperative phase. Alternately, this discrepancy may indicate the holistic approach of the FDQ, whereby functional difficulty is not only dependent on physical capabilities, but also on emotional and mental aspects at this time point. This is an important finding, as up to half of people after cardiac surgery report depressive symptoms,24 which are associated with a slow recovery and worse functional status.24–26 Furthermore, researchers have found an interdependence between physical and psychological wellbeing,26 and so although each of the FDQ tasks is physical in nature, the subjective rating scale may be influenced by these factors.
Assessments conducted 4 weeks after discharge demonstrated the strongest associations between various measures of pain (SF36 bodily pain r = 0.51, thoracic pain r = 0.52, and total pain = 0.68). Interestingly, although there was ongoing moderate to good correlations between the FDQ score and total pain (r = 0.55) when assessed 3 months after operation, other measures of pain demonstrated only a fair degree of relationship20 and were much stronger with SF36 items role physical, bodily pain, vitality, and social function (r = −0.63 to −0.65). General health (r = −0.54) also showed a moderate to good correlation. This supports that the FDQ not only measures pain, and after people recover from the early effects of surgery it also assesses HRQOL.
The weaker correlations between the FDQ and ROM/TUG across all assessments indicate that people's functional status after cardiac surgery is more closely associated with pain and HRQOL aspects as opposed to ROM or functional mobility. Although these correlations do not contribute substantially to the convergent validity, they do perhaps highlight the notion that the FDQ is measuring a domain of function that is not currently measured by the existing tools. The investigators reviewed upper extremity questionnaires and tools before developing the FDQ because of the close relationship between pain and range of movement of the thoracic spine and shoulder.27–29 Although these questionnaires contain elements that would be applicable to patients having cardiac surgery through a sternotomy incision, no single tool provided a comprehensive assessment for the thoracic region. For example, tasks such as coughing/sneezing and getting in/out of bed are more specific to the thoracic region and are not found in upper extremity–based tools.30,31 Furthermore, some tasks within the upper extremity tools (e.g. writing, recreational activities which require little effort, such as knitting)30 are unlikely to be relevant for people after cardiac surgery.
The FDQ displayed a responsiveness to change, with significant changes in scores over time. The responsiveness was highest between preoperation to the time of discharge postoperation and the time of discharge from hospital postoperatively to 4 weeks postoperatively, which co-relates with the time where most people report sternal pain and difficulty performing functional tasks during recovery from the surgical procedure.16
The FDQ has excellent test–retest reliability (ICC 0.918),21 and so this inexpensive tool can be effectively completed and easily administered in the clinical setting with little training required. The Bland–Altman plot revealed little variability between tests. The MDC of 16.35 cm indicates that the difference in FDQ scores from preoperatively to before hospital discharge postoperatively and before hospital discharge to 4 weeks postdischarge are not only statistically significant but also clinically meaningful.
Functional assessments after cardiac surgery are of importance to comprehensively evaluate outcomes, and so this tool has an important purpose both clinically and in research. The FDQ may be of use to evaluate effectiveness of other research and interventions in people undergoing cardiac surgery, as well as other groups, such as those after thoracic surgery.
A major limitation in establishing validity of the FDQ is that there is no true gold standard for function of the thoracic region to act as a comparison for concurrent validity. Furthermore, there was a lack of any tool specific to the thoracic region and suitable for use in people having cardiac surgery through a sternotomy incision. This includes upper extremity questionnaires and tools. Future research comparing the FDQ with other upper extremity tools may be of interest.
The FDQ was developed in Australia, and so there are cultural differences in language between Australia and the United States, for example dressing gown versus robe, cardigan versus sweater, which are component tasks within the FDQ. As such, the tool may require modifications to accommodate cultural and linguistic variations.
Functional Difficulties Questionnaire assessments for test–retest reliability were separated by as little as 2 hours. This was a necessary compromise between research and practicality requirements, as some assessments occurred within a busy acute hospital and often on the day of discharge. This is the time when patients have reviews by a number of health professionals (e.g. pharmacist, nursing, medical, and allied health), in addition to getting themselves ready for home. A longer time separation between assessments posed a risk to delaying patient flow within the hospital by delaying discharges, or missing assessments altogether. However, there was the possibility that individuals may have remembered how they initially scored the FDQ, and this could impact on the test–retest reliability results. Intuitively, it would seem that markings made on a VAS would be less likely to be remembered than other forms of scoring, such as Likert scales, and the volume of activity before discharge may have minimized this likelihood.
It is possible that pain may have had an impact on FDQ scores between tests for the test–retest reliability study. Therapists ensured individuals had received charted analgesia, and that this had occurred at least 30 minutes before commencement of the FDQ; however, it is still possible that variations in pain levels may have occurred and this is a limitation of the study.
The FDQ is a reliable, responsive, and valid tool and it has demonstrated good internal consistency in the cardiac surgery population. It may be suitable for use by clinicians and researchers investigating the thoracic region, as there is no alternative tool that specifically evaluates physical function or the effectiveness of interventions in this area. As such, the FDQ warrants further investigation in varied surgical and medical populations.
The authors acknowledge Alexandra Cain, who assisted with data collection for part B.
Functional Difficulties Postcardiac Surgery Questionnaire
Please mark on each of the lines below the level of difficulty that you experience when completing each of the following tasks. Make sure you read each question fully, as it will explain to you the exact way in which the task has to be completed.
Feel free to try any of the activities (where appropriate) while you are completing the questionnaire. For those activities you cannot trial whilst filling out the questionnaire, think back to the last time you did them.
Functional Difficulties Questionnaire Postcardiac Surgery Outcome Measure Protocol Equipment:
- Subject sits at a desk/table to complete the survey
- Questionnaire is given to subject
- Subject reads questionnaire
- Verbal instructions given by clinician/researcher on how to complete the questionnaire
- Subjects can ask any questions
- Subject completes questionnaire
Instructions to Subject:
- For each activity listed, you need to place a mark on the line which corresponds to how much difficulty you experience when completing the task
- (Demonstrate to subject)
- If you experience no difficulty at all, your mark will be at the far left hand side of the line
- If you experience maximal difficulty, your mark will be at the far right hand side
- You can place the mark anywhere along the line, which you feel represents how much difficulty you experience
- Feel free to try any of the activities, where possible, to help you fill out the questionnaire
- For the activities that you cannot try now, think back to the last time you did them
- The clinician/researcher will redirect the subject if they do not place a single, vertical mark on the line. The following redirection will be provided:
- In the event a mark is not placed on the line, the clinician/researcher will direct as follows, “You need to place your mark somewhere along this line. At this end (demonstrating) it means you experience no difficulty at all, and it gradually increases as you move along the line, so that at this end (demonstrating) it means you experience maximal difficulty.”
- In the event the mark is not vertical, the clinician/researcher will direct as follows, “You need to place your mark as a line running top to bottom, like this (drawn demonstration).”
- In the event, several marks are placed on the line for a single task, the clinician/researcher will direct as follows, “You can only place a single mark somewhere along this line. Choose how much discomfort you experience when you complete the task now/when you last completed the task (dependent on the task).”
- If the subject reports they cannot complete the task the researcher will score the task as a 10, to indicate maximal difficulty.
- Verbal feedback otherwise:
- Just place the mark where you feel is appropriate
Participant FDQ Full Results, Across All 4 Time Points, Used for Determining Internal Consistency and Responsiveness to Change
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Keywords:© 2018 Cardiovascular and Pulmonary Section, APTA
cardiac surgery; sternotomy; physical therapy; outcome measure; function; thoracic region