Verbal numerical scales are as reliable and sensitive as visual analog scales for rating dyspnea in young and older subjects

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Abstract

This study compared the use of a simple verbal 0–10 numerical rating scale (verbal NRS) and a visual analog scale (VAS) for the rating of dyspnea during exercise in a group of young and older subjects. Twelve younger (32 ± 9 yr) and 12 older (71 ± 7 yr) subjects used either the verbal NRS or the VAS in a randomised fashion to rate dyspnea during 60 s of uphill treadmill walking (range 5.6–8.8 km h−1) performed at either a low (17% grade) or high workload (26% grade) and then during recovery. Rating scales were evaluated twice on separate days (day 1 and day 2) at each workload. While the verbal NRS scores proved to be reliable throughout exercise and recovery, VAS scores were significantly (p < 0.05) lower on day 2 during the low workload test (younger group) and the high workload test (older group). Verbal NRS ratings were consistently greater than VAS ratings at both workloads (p < 0.001) for both young and older groups. The intra-class correlation coefficients for rating peak dyspnea using either the VAS or verbal NRS were consistently lower for the older subjects (range: r = 0.54–0.67) than the younger subjects (range: r = 0.70–0.86). Overall, subjects preferred the verbal NRS to the VAS. These results suggest that the verbal NRS compares favourably with the VAS for rating dyspnea during exercise without mask or mouthpiece. However, when rating peak dyspnea both scales appear less reliable when used by the older compared to young 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)

  • J.G.W. Burdon et al.

    The perception of breathlessness in asthma

    Am. Rev. Resp. Dis.

    (1982)
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