Verbal numerical scales are as reliable and sensitive as visual analog scales for rating dyspnea in young and older subjects
Introduction
The measurement of dyspnea is a useful outcome measure for assessing symptoms which limit exercise performance and for evaluating interventions designed to relieve this symptom in a variety of populations (Mahler, 2006, Mahler et al., 2006). A number of scales are used to rate the intensity of dyspnea during exercise including the Borg scale, the visual analog scale (VAS) and, to a lesser extent, the numerical rating scale (verbal NRS).
Numerical rating scales (e.g., 0–10) are more commonly used in a clinical setting for the assessment of pain and discomfort (Jensen et al., 1986, Ekblom and Hansson, 1988). The verbal NRS is relatively simple to understand and administer since it does not require the use of written, mechanical or electronic instruments. There is some evidence to suggest that when rating pain, the verbal NRS is more reliable than the VAS (Ferraz et al., 1990). More recently, Rodriguez and colleagues reported that older individuals with head and neck cancer preferred using the NRS compared to the VAS to rate pain (Rodriguez et al., 2004).
Scales for rating dyspnea are typically used in older aged clinical populations (Powers and Bennett, 1999, Martinez et al., 2000). To our knowledge, the effect of age on the use of different scales to rate dyspnea has not been reported. Studies examining the effect of age when rating pain have reported that older subjects may find the VAS a difficult scale to use (Bird, 2003), and that there may be some age-specific differences when using different pain rating scales (Gagliese and Katz, 2003).
While the NRS has been validated in assessing resting dyspnea in chronic obstructive pulmonary disease (COPD) patients (Gift and Narsavage, 1998, Powers and Bennett, 1999, Martinez et al., 2000), to date, there has been no comparison of the reliability or sensitivity of the verbal NRS and the VAS during an exercise challenge in healthy older individuals.
Therefore, the primary purpose of this study was to compare the reliability and sensitivity of the simple 0–10 verbal NRS with the VAS over a time period of exercise and recovery in a group of young and older subjects. We chose to compare the verbal NRS to the VAS rather than to the Borg scale because of concern that the use of the Borg scale with its numbers as well as words might influence the subjects in their use of the verbal NRS. The choice of the VAS as the reference scale is further justified by reports of its close comparability to the Borg scale (Wilson and Jones, 1989, Muza et al., 1990). We asked subjects to use either the VAS or verbal NRS in randomised fashion to rate their dyspnea during and immediately following a 60 s uphill treadmill walk at two different grades (low and high workload).
Section snippets
Subjects
The Charing Cross Hospital Ethical Committee and the Griffith University Human Ethics Committee approved this study and all subjects provided written informed consent. Twelve healthy younger subjects (5 women, 7 men) aged 32 ± 9 yr (mean ± S.D.) and 12 healthy older subjects (4 women, 8 men) aged 71 ± 7 yr volunteered to participate in this particular study. All subjects had normal resting spirometry, peak expiratory flow rates and no history of lung or heart disease or other medical problems that
Reliability of rating scales
The mean ratings of dyspnea using the verbal NRS and the VAS on day 1 and day 2 of the study are presented in Fig. 1. For both the young (Fig. 1, Panel A) and older groups (Fig. 1, Panel C), dyspnea ratings using the verbal NRS were reliable, with no significant differences between day 1 and day 2 at either workload.
In contrast, the VAS did not provide consistent results across day 1 and day 2 for the young (Fig. 1, Panel B) and older subjects (Fig. 1, Panel D). For the younger subjects, the
Discussion
The present study demonstrated that in a group of young and older subjects the verbal NRS is as reliable and sensitive as the VAS to changes in dyspnea during exercise. Our findings are consistent with those of Gift and Narsavage (1998) who validated the NRS with the VAS to measure resting dyspnea in COPD patients.
When using the verbal NRS subjects were instructed to rate their dyspnea by giving verbal responses from 0 to 10 with half steps permitted. All but five of the 24 subjects (one young
Conclusion
This study has shown that a simple numerical scale (verbal NRS) is sensitive and reliable for measuring the sensation of dyspnea during exercise in both young and older subjects. Moreover, the verbal NRS is easily learned, appears to be more reliable than the VAS in rating dyspnea, and is generally preferred over the VAS by naive subjects during a short exercise bout. The availability of such a simple instrument should encourage greater and more effective use of rating dyspnea in both research
Acknowledgments
This work was supported by the Breathlessness Research Charitable Trust, United Kingdom. This study is dedicated to the memory of our friend and colleague Michael Stulbarg who passed away in 2004.
References (22)
- et al.
Age differences in postoperative pain are scale dependent: a comparison of measures of pain intensity and quality in younger and older surgical patients
Pain
(2003) - et al.
The measurement of clinical pain intensity: a comparison of six methods
Pain
(1986) - et al.
What is the maximum number of levels needed in pain intensity measurement?
Pain
(1994) - et al.
Dyspnea scales in the assessment of illiterate patients with chronic obstructive pulmonary disease
Am. J. Med. Sci.
(2000) - et al.
An exercise test to assess clinical dyspnoea: estimation of reproducibility and sensitivity
Br. J. Dis. Chest
(1982) - et al.
The measurement of breathlessness induced in normal subjects: individual differences
Clin. Sci.
(1986) - et al.
The measurement of breathlessness induced in normal subjects: validity of two scaling techniques
Clin. Sci.
(1985) Selection of pain measurement tools
Nurs. Stand.
(2003)- et al.
Measuring agreement in method comparison studies
Stat. Methods Med. Res.
(1999) Psychophysical bases of perceived exertion
Med. Sci. Sports Exerc.
(1982)
The perception of breathlessness in asthma
Am. Rev. Resp. Dis.
Cited by (34)
Examining the repeatability of a novel test to measure exertional dyspnoea in chronic obstructive pulmonary disease
2022, Respiratory Physiology and NeurobiologyCitation Excerpt :The modified Borg has been shown to have limitations in that there is user bias towards numbers with a categorical label (Johnson et al., 2016). Importantly, the 0−10 NRS has been shown to be a valid measure of ED during exercise in both young and older adults but to a lesser degree (Morris et al., 2007; Johnson et al., 2016). Walk speed was set at 80 % of the 6MWT to ensure each participant exercised at an individualised intensity that was high but tolerable, and aligned with exercise intensities utilized in pulmonary rehabilitation programmes (Zainuldin et al., 2015).
Dyspnea in Patients Receiving Mechanical Ventilation
2021, Encyclopedia of Respiratory Medicine, Second EditionTo What Extent Do the NRS and CRQ Capture Change in Patients' Experience of Breathlessness in Advanced Disease? Findings From a Mixed-Methods Double-Blind Randomized Feasibility Trial
2019, Journal of Pain and Symptom ManagementCitation Excerpt :The NRS was originally validated with the statement “Indicate how much shortness of breath you are having right now.”18 The accompanying statement/question has evolved over time with studies increasingly reporting an assessment of average (NRS average) and worst (NRS worst) breathlessness over the past 24 hours (Appendix I).20–31,41,42 Even the wording used to describe “worst breathlessness” varies, with one study asking participants “What is the worst your breathlessness has been over the last 24 hours?”
- ✠
Deceased.