Respiratory parameters predict poor outcome in COPD patients, category GOLD 2017 B

Abstract

Background

Respiratory parameters are important predictors of prognosis in the COPD population. Global Initiative for Obstructive Lung Disease (GOLD) 2017 Update resulted in a vertical shift of patients across COPD categories, with category B being the most populous and clinically heterogeneous. The aim of our study was to investigate whether respiratory parameters might be associated with increased all-cause mortality within GOLD category B patients.

Methods

The data were extracted from the Czech Multicentre Research Database, a prospective, noninterventional multicenter study of COPD patients. Kaplan–Meier survival analyses were performed at different levels of respiratory parameters (partial pressure of oxygen in arterial blood [PaO₂], partial pressure of arterial carbon dioxide [PaCO₂] and greatest decrease of basal peripheral capillary oxygen saturation during 6-minute walking test [6-MWT]). Univariate analyses using the Cox proportional hazard model and multivariate analyses were used to identify risk factors for mortality in hypoxemic and hypercapnic individuals with COPD.

Results

All-cause mortality in the cohort at 3 years of prospective follow-up reached 18.4%. Chronic hypoxemia (PaO₂ <7.3 kPa), hypercapnia (PaCO₂ >7.0 kPa) and oxygen desaturation during the 6-MWT were predictors of long-term mortality in COPD patients with forced expiratory volume in 1 second ≤60% for the overall cohort and for GOLD B category patients. Univariate analyses confirmed the association among decreased oxemia (<7.3 kPa), increased capnemia (>7.0 kPa), oxygen desaturation during 6-MWT and mortality in the studied groups of COPD subjects. Multivariate analysis identified PaO₂ <7.3 kPa as a strong independent risk factor for mortality.

Conclusion

Survival analyses showed significantly increased all-cause mortality in hypoxemic and hypercapnic GOLD B subjects. More important, PaO₂ <7.3 kPa was the strongest risk factor, especially in category B patients. In contrast, the majority of the tested respiratory parameters did not show a difference in mortality in the GOLD category D cohort.

Keywords:

• mortality
• hypoxemia
• hypercapnia
• COPD
• GOLD 2017 update

Supplementary materials

Table S1 Frequency of desaturation (n=552)

Table S2 (A) Prediction of all-cause mortality – multivariate analysis containing PaCO₂ (kPa) – categories (<5; 5–7 – reference; >7). (B) Prediction of all-cause mortality – multivariate analysis containing desaturation. (C) Prediction of mortality by parameters of blood gases – ideal cutoff values. (D) Prediction of mortality – multivariate analysis containing PaO₂ (kPa) ≤7.1.

Table S3 Relationship between comorbidities and all-cause mortality (A); relationship between comorbidity and PaO₂ (B); relationship between comorbidity and PaCO₂ (C)

Table S4 Comparison of parameters between groups according to valid data (n=725)

Table S5 SpO₂ according to physical examination (n=725) (A), correlation between SpO₂ (physical examination*) and SpO₂ (6-MWT°) (n=552) (B)

Acknowledgments

We thank the physicians of participating centers of the Czech multicenter research database of severe COPD, namely, Tomas Dvorak – Pulmonary Department, Hospital Mlada Boleslav, Petr Safranek – Pulmonary Department, University Hospital, Plzen, Ondrej Sobotik – Pulmonary Department, University Hospital Motol, Prague, Maria Majerciakova – Pulmonary Department, Hospital of St Svorad, Nitra, Slovakia, Jaroslav Lnenicka – Pulmonary Department, Masaryk Hospital, Usti nad Labem, Pavlina Musilova – Pulmonary Department, Jihlava Hospital, Barbora Novotna – Pulmonary Department, Bulovka Hospital, Prague, Zuzana Liptakova – Pulmonary Department, Ceske Budejovice Hospital, Eva Kocova, Michal Kopecky, Sarka Pracharova, Libor Nevoranek and Lukas Varhanik – University Hospital Hradec Kralove, Katerina Neumannova – Palacky University, Olomouc and Milada Sipkova – Pulmonary Department, Liberec Hospital. Special thanks to Ondrej Zindr – Karlovy Vary for English corrections. This research was funded by Ministry of Health of the Czech Republic (15/14/NAP, 5/15/NAP, and UHHK, 00179906), moreover by consortium of several pharmaceutical companies (Angelini CZ, AstraZeneca CZ, Boehringer Ingelheim CZ, Cipla CZ, CSL Behring CZ, GSK CZ, Novartis CZ and Sandoz CZ).

Disclosure

M Plutinsky has received payments on COPD lectures from Boehringer Ingelheim. P Popelkova has received consulting/lectures payment from AstraZeneca, Boehringer Ingelheim and Novartis regarding the COPD field within past 36 months. J Zatloukal has received payment related to COPD clinical trials from AstraZeneca, GSK and Novartis within past 36 months, and received consulting/lectures payment from AstraZeneca, Novartis, Angelini and Berlin-Chemie regarding the COPD field within past 36 months. E Volakova has received COPD research funding from GSK within past 36 months, and received consulting/lectures payment from Boehringer Ingelheim and Berlin-Chemie regarding the COPD field within past 36 months. L Heribanová has received COPD research funding from AstraZeneca within past 36 months. V Koblizek has received COPD research funding from Boehringer Ingelheim, and Novartis within past 36 months, and received consulting/lectures payment from Angelini, AstraZeneca, Berlin-Chemie, Boehringer Ingelheim, GSK, Mundipharma, Novartis and Sandoz regarding the COPD field within past 36 months. K Brat, K Hejduk, M Svoboda and M Fecaninova have not received any payments within past 36 months. The authors report no other conflicts of interest in this work.