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Exertional Desaturation as a Predictor of Rapid Lung Function Decline in COPD.
Kim, Changhwan a, d; Seo, Joon Beom b; Lee, Sang Min b; Lee, Jae Seung c, d; Huh, Jin Won c, d; Lee, Jin Hwa d, e; Ra, Seung Won d, j; Lee, Ji-Hyun d, k; Kim, Eun-Kyung d, k; Kim, Tae-Hyung d, m; Kim, Woo Jin d, n; Lee, Sang-Min d, f; Lee, Sang Yeub d, g; Lim, Seong Yong d, h; Shin, Tae Rim d, i; Yoon, Ho Il d, l; Sheen, Seung Soo d, o; Oh, Yeon-Mok c, d; Park, Yong Bum a, d; Lee, Sang-Do c, d
[Article] Respiration. 86(2):109-116, August 2013.

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Background: To date, no clinical parameter has been associated with the decline in lung function other than emphysema severity in COPD.

Objectives: The main purpose of this study was to explore whether the rate of lung function decline differs between COPD patients with and without exertional desaturation.

Methods: A total of 224 subjects were selected from the Korean Obstructive Lung Disease cohort. Exertional desaturation was assessed using the 6-min walk test (6MWT), and defined as a post-exercise oxygen saturation (SpO2) of <90% or a >=4% decrease. The cohort was divided into desaturator (n = 47) and non-desaturator (n = 177) groups.

Results: There was a significant difference between the desaturator and non-desaturator groups in terms of the change in pre-bronchodilator forced expiratory volume in 1 s (FEV1) over a 3-year period of follow-up (p = 0.006). The mean rate of decline in FEV1 was greater in the desaturator group (33.8 ml/year) than in the non-desaturator group (11.6 ml/year). A statistically significant difference was also observed between the two groups in terms of the change in the St. George's Respiratory Questionnaire (SGRQ) total score over 3 years (p = 0.001).

Conclusions: This study suggests, for the first time, that exertional desaturation may be a predictor of rapid decline in lung function in patients with COPD. The 6MWT may be a useful test to predict a rapid lung function decline in COPD.