At present, the number of deaths from respiratory diseases accounts for a quarter of all deaths, with COPD accounting for a large proportion . QOL is an important indicator of the effectiveness of disease prevention and treatment measures  as well as a sensory representation of a person’s physical, mental, and social abilities.
Comparison of the average scores for patients with COPD in various domains after standardization revealed that social function had the highest score, followed by psychological function and the score for the disease-special module, which reflects COPD symptoms. Physiological function had the lowest score. Physiological function mainly reflects a patient's appetite, sleep, defecation, and other basic physiological functions, as well as pain and fatigue. The average score for this domain was low, possibly because COPD is a lung disease that limits airflow, which can seriously damage the human body, mostly due to chronic bronchitis and bronchial asthma complicated by emphysema. There is no method to cure COPD currently and the only available options are for controlling infection and treating symptoms using anti-spasmodic and anti-asthmatic drugs. COPD has many complications, such as chronic pulmonary heart disease, diabetes mellitus, cardiovascular and cerebrovascular diseases, cerebrovascular diseases, dyslipidemia, and peptic ulcer, and severe disease will directly result in the death of the patient. The etiology of the disease is related to hypoxia, high blood viscosity, capillary spasms, and long-term use of glucocorticoids and other drugs . The average age of the participants in this study was 71 years. Most of the current research results suggest that there is a correlation between the age of patients and their QOL. Some researchers think age is an independent determinant of QOL for patients with COPD. With the increase of age, elderly patients with COPD develop more complications, which may affect their QOL .
The psychological function mainly reflects the mental status of patients, including the three aspects of cognition, emotion, will and personality. Chronic diseases tend to increase an individual’s susceptibility to emotional depression and produce a long-lasting decrease in mood . Depression, anxiety, and other emotional disorders have an important impact on the QOL of patients. The incidence of depression among patients with COPD is higher than that in healthy individuals. Prigatano et al. found that depression and anxiety were highly correlated with QOL among patients with COPD using the Profile of Mood States . Individuals with COPD also experience significant changes in their mental health when they suffer from long-term physical pain; hence, they tend to have a low psychological function score.
Because the factors that affect QOL in patients with COPD vary, including social and demographic factors, physical factors, psychological factors, and clinical factors , we used canonical correlation analysis to comprehensively assess the group relationships for multiple factors. Canonical correlation analysis showed that in the first pair of canonical variables, lower levels of TP, ALB, and LYMPH% in blood biochemistry and higher levels of NEUT% in blood routine tests were correlated to lower scores for psychological function and the disease-specific module as well as worse QOL. TP consists of ALB and globulin and low levels of TP and ALB usually indicate a poor nutritional status. Patients should eat a light diet with a rich and reasonable nutrition, drink adequate amounts of water, rest sufficiently, perform physical exercise, reduce excess fat, burn excess calories, etc. . Both LYMPH and NEUT are white blood cells. Researchers have found that many lung diseases are characterized by excessive NEUT, which leads to inflammatory responses such as pneumonia and bronchiectasis. A large number of NEUT can be found in the airway walls and lung tissues of patients with COPD and the concentration and infiltration of NEUT in the airways and lung tissues are related to the severity and progression of lung infection [21, 22]. In the second pair of canonical variables, lower levels of serum Nain blood biochemistry and higher levels of ALP were correlated with lower social function scores and worse QOL. Acid-base disturbances and electrolyte disturbances are common among patients with obstructive pulmonary disease because of decreased lung function and ventilatory disturbances. Low serum Na in the body leads to hyponatremia, which can cause nausea, vomiting, bloating, and drowsiness and makes the patient believe the condition is more serious. This leads to a negative state of mind, influences the life and interpersonal relationships of patients, and seriously affects their quality of life. Shi  also reached the same conclusion. Bruno et al.  described the pathophysiological mechanisms of acid-base disorders and their impact on patient mortality, and noted that paying attention to the serum Na in the blood is helpful for correct diagnosis and targeted therapy. ALP is an indicator of liver function and is widely distributed in various organs of the body. Mosqueira et al.  found that ALP in tissues is involved in lipid metabolism and related gene expression. Hepatobiliary disease or bone disease can lead to elevated ALP, which affects the patient's position in their family and at work, reduces the amount of contact with other people, and affects their QOL.
In this study, the lack of some clinical objective indicators is a serious limitation. Because these objective indicators were not included in the relevant statistical analysis, the final results were affected. In subsequent questionnaire collection processes, the accuracy and integrity of the data will be guaranteed as much as possible and priority will be given to patients who are not within the normal range for the indicators. Redundancy analysis results showed that two pairs of canonical variables related to the QOL had a low explanatory value. The selected clinical objective indicators only reflect a small portion of the factors that influence QOL and many other factors can affect the QOL of patients with COPD. Therefore, social demographic factors, physical and psychological factors, clinical factors, and other factors should be taken into account for the development and application of scales and records of clinical objective indicators.
To summarize, among the clinical objective indicators evaluated for patients with COPD, the levels of TP, ALB, NEUT%, LYMPH%, serum Na, and ALP can partly reflect the patient's QOL. In the course of treatment, clinicians should pay close attention to increases in ALP and NEUT% as well as decreases in TP, ALB, LYMPH%, and serum Na. While using drugs and other therapeutic means to ease the patient’s pain, health education and psychological treatment should also be provided. Physicians need to consider the various factors that affect the patient and take appropriate steps to improve their QOL.