The decrease in clinical efficacy of oxygen therapy takes place in patients suffering from chronic pulmonary obstructive disease who continue smoking even if the intensity of smoking is getting lower. It is explained by the damage of oxygen utilization regardless of normalization of arterial blood saturation indices and perfusion oxygen saturation indices in blood flow.
Nikolay I. Starodumov, E.G. Zarubina and I.O. Prokhorenko Comparative efficiency of oxygen therapy in patients (smokers and non-smokers) with chronic obstructive pulmonary disease // Russian Open Medical Journal, Vol. 1, Issue 2, 2012, pp. 207-0

Comprehensive analysis of the impact of complex vaccination against pneumococcus, Haemophilus influenzae type b and influenza on performance CAT-test 6 months after vaccination in patients with chronic obstructive pulmonary disease compared with unvaccinated patients. 1 group - 48 patients with chronic obstructive pulmonary disease, vaccinated simultaneously «Pneumo-23», «Hiberix», «Grippol plus» (mean age - 61,46±1,17 years). Group 2-80 non-vaccinated patients with chronic obstructive pulmonary disease (mean age - 54,65±0,6 years). Patients from both groups held CAT-test at baseline and 6 months after. There was a significant decline in CAT-test after 6 months in the vaccinated patients compared with unvaccinated patients with chronic obstructive pulmonary disease. CAT-test can be used as a sensitive tool to monitor indicators of quality of life in patients with chronic obstructive pulmonary disease in the process of therapy. Complete vaccination against pneumococcus, Haemophilus influenzae type b infection and influenza contributes to improving the quality of life in patients with chronic obstructive pulmonary disease in 6 months after medical intervention
Protasov A.D., Zhestkov A.M, Shanina I.Yu. CAT-test significance in life quality assessment in patients with chronic obstructive pulmonary disease // Saratov Journal of Medical Scientific Research, Vol. 6, Issue 3, 2010, pp. 588-592