Assessment of Breathlessness Perception by Borg Scale in Asthmatic Patients: Reproducibility and Applicability to Different Stimuli

Abstract

In asthmatics, the score of bronchoconstriction-associated breathlessness at 20% fall in forced expiratory volume at first second (FEV₁) evaluated on a Borg scale (PS₂₀) is a tool successfully used to measure the perception of symptoms. This prospective laboratory study evaluated the applicability of PS₂₀ to assess the breathlessness induced by ultrasonically nebulized distilled water (UNDW) and methacholine (M) and its reproducibility. Twenty-two mild and clinically stable asthmatic patients performed UNDW and M challenge tests. The PS₂₀ was calculated by linear interpolation of the last two points of the perception/fall in FEV₁ curve of the UNDW and M tests. The reproducibility of PS₂₀ M was assessed by repeating measurements on 2 separate days by 3 weeks. PS₂₀ UNDW and PS₂₀ M did not differ and were respectively 1.82 ± 1.85 and 2.03 ± 1.86. They were significantly related (r_s = 0.63; p<0.01) and the bias between PS₂₀ UNDW and PS₂₀ M was –0.21 with the limits of agreement ranging from –3.2 to 3.6. The intraclass correlation coefficient for repeated measurement of PS₂₀ M was 0.82; the bias between the two measurements was 0.2 with the limits of agreement ranging from –2.8 to 3.2. All patients had a measurable breathlessness perception degree on a Borg scale during both distilled water challenges and methacholine. Asthmatic patients with normal, exaggerated or poor breathlessness perception were also similar for both stimuli. In addition, PS₂₀ showed a good reproducibility and this allows the serial evaluation of patient's breathlessness perception by this technique in clinical settings and in the physiology laboratory.

• Asthma
• Dyspnea
• Borg scale

Abbreviations
UNDW:	=	Ultrasonically nebulized distilled water;
M:	=	Methacholine;
PS20:	=	Perception score of bronchoconstriction associated breathlessness at 20 percent fall in FEV1 evaluated on a Borg scale.